kinetic studies of the chirality inversion of salicylaldiminato ruthenium using racemic h6-p-cymene...

DOI: 10.1002/ejic.201600221 Full Paper

Chirality Inversion

Kinetic Studies of the Chirality Inversion of Salicylaldiminato–Ruthenium Using Racemic η6-p-Cymene Complexes as aMechanistic ProbeNaruyoshi Komiya,*[a,b] Tomoko Nakajima,[a] Masato Hotta,[a] Takatoshi Maeda,[a]

Tatsuya Matsuoka,[a] Soichiro Kawamorita,[a] and Takeshi Naota*[a]

Abstract: Kinetic studies of the chirality inversion of a series ofmono- and bimetallic (p-cymene)(salicylaldiminato)RuII com-plexes with halo ligands (1 and 2) in solution have been per-formed by means of the line-shape method, using 1H NMRspectroscopy to evaluate the signal exchange rates betweendiastereotopic protons in the p-cymene ligand. The activation

IntroductionThe chirality inversion of optically active transition-metal com-plexes incorporating chiral metal centers is an important aspectof elucidating the dissociation mechanisms of these com-plexes.[1] Such inversions also suggest the possibility of using3D molecular mobility to produce controlled junctions in mo-lecular machinery. The rates of chirality inversions of pseudo-tetrahedral metal complexes have been determined by directobservation of the specific rotations of optically pure (η5-C5H5)Mn complexes[2] and also by 1H NMR analyses of the epi-merizations of diastereomers of (η5-C5H5)Fe,[3a–3c,4] (η5-C5H5)Ru,[3d,3e] (η6-C6R5)Ru,[5,8] (η5-C5Me5)Ir,[6] and (η7-C7H7)Mo[7]

Scheme 1. (η6-p-Cymene)(salicylaldiminato)ruthenium(II) complexes 1–3.

[a] Department of Chemistry, Graduate School of Engineering Science, OsakaUniversity,Machikaneyama, Toyonaka, Osaka 560-8531, JapanE-mail: [email protected]://www.soc.chem.es.osaka-u.ac.jp/index.html

[b] Chemistry Laboratory, The Jikei University School of Medicine,Kokuryo, Chofu, Tokyo 182-8570, JapanE-mail: [email protected] information and ORCID(s) from the author(s) for this article areavailable on the WWW under http://dx.doi.org/10.1002/ejic.201600221.

Eur. J. Inorg. Chem. 2016, 3148–3156 © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim3148

parameters (ΔH‡ and ΔS‡) associated with the flipping molecu-lar mobility were determined from variable-temperature NMRanalyses, and it was found that the neutral halo complexes 1and 2 exhibit much lower enthalpies and entropies than thecorresponding cationic pyridine analogues 3.

complexes with chiral ligands such as diphosphine,[3] amino-phosphane,[4] salicylaldimine,[5] iminopyrrole,[6] iminopyrid-ine,[7] and o-aminomethylphenyl.[8] Alternative indirect meth-ods for the evaluation of inversion rates include estimating theexchange rates of NMR signals from the diastereotopichydrogen[9] and phosphorus[10] atoms of the optically activeligands based on coalescence[9] and line-shape[10] methods us-ing variable-temperature NMR spectroscopy.

As part of our program aimed at developing new uses formobile salicylaldiminato metal complexes,[11–13] we have devel-oped a convenient process for determining the inversion ratesof chiral (η6-p-cymene)(salicylaldiminato)ruthenium(II) com-

plexes [p-cymene: 1-methyl-4-(1′-methylethyl)benzene][5] basedon the exchange of signals between diastereotopic protons Ha/Hb (or Hc/Hd) in the p-cymene ligand [Equation (1)] in conjunc-tion with a 1H NMR line-shape method.[14] This represents aneffective means of evaluating the inversion rates of chiral (η6-benzene) metal complexes in solution, because the inversionrates can be conveniently determined by using a racemic mix-ture of complexes bearing achiral salicylaldiminato ligands, and

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because the method is applicable to complexes with labile haloligands. This is helpful because the rates of inversion of suchcomplexes cannot be estimated by the direct method usingdiastereomers[5] due to their rapid inversion even at lower tem-peratures.[15,16] This paper describes the synthesis, structure,and chirality inversion of mono- and dinuclear ruthenium halidecomplexes bearing p-cymene and salicylaldiminato ligands (1and 2; Scheme 1), with a focus on the mechanistic aspects oftheir dynamic flipping behavior in the solution state.

(1)

Figure 1. ORTEP drawings of (a) 1a, (b) 2aa, and (c) 2dc. Thermal ellipsoids are shown at the 50 % probability level. Crystalline 1a is racemic, whereascrystalline 2aa and 2dc are in the meso state. Selected bond lengths [Å] and angles [°]: 1a: Ru1–O1 2.0799(10), Ru1–N1 2.1130(12), Ru1–Cl1 2.4352(4), O1–Ru1–N1 86.06(4), Cl1–Ru1–O1 83.89(3), Cl1–Ru1–N1 90.43(4). 2aa: Ru1–O1 2.069(8), Ru1–N1 2.085(10), Ru1–Cl1 2.413(4), O1–Ru1–N1 87.7(4), Cl1–Ru1–O187.3(3), Cl1–Ru1–N1 82.2(3). 2dc: Ru1–O1, 2.055(3), Ru1–N1 2.089(3), Ru1–Cl1 2.4294(8), O1–Ru1–N1 88.40(9), Cl1–Ru1–O1 85.43(7), Cl1–Ru1–N1 84.75(7).

Table 1. Crystal data and structural refinement details for compounds 1a, 2aa, and 2dc.

1a 2aa 2dc

Formula C25H36ClNORu C46H62Cl2N2O2Ru2 C40H50Cl2N2O2Ru2

MF 503.09 948.05 863.89T [K] 121 163 120Crystal color, habit brown, block brown, needle brown, blockCrystal size [mm] 0.50 ×0.40 ×0.30 0.40 ×0.05 ×0.05 0.40 ×0.30 ×0.05Crystal system monoclinic monoclinic monoclinicSpace group P21/c (#14) P21/c (#14) P21/c (#14)a [Å] 13.1209(5) 6.5686(3) 19.3598(7)b [Å] 12.1163(5) 20.1124(11) 7.6246(3)c [Å] 15.5161(7) 16.1298(9) 12.6479(4)α [°] 90 90 90� [°] 100.7898(14) 85.418(3) 101.3892(15)γ [°] 90 90 90V [Å3] 2423.07(17) 2124.10(19) 1830.20(11)Z 4 2 2Dcalcd. [g cm–3] 1.379 1.482 1.567μ(Mo-Kα) [cm–1] 7.726 8.765 10.089F(000) 1048.00 980.00 884.002θmax [°] 54.8 55.0 55.0Number of measured reflections 47383 39617 35963Number of observed reflections 5500 4865 4186Number of variables 278 248 217R1 [I > 2σ(I)][a] 0.023 0.110[c] 0.032wR2 (all reflections)[b] 0.057 0.276[c] 0.074Goodness of fit 1.08 1.16 1.14

[a] R1 = Σ(|Fo| – |Fc|)/Σ(|Fo|). [b] wR2 = {Σ[w(Fo2 – Fc

2)2]/Σw(Fo2)2}1/2. [c] The relatively poor R values are due to the needle shape of the crystal.

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Results and Discussion

Synthesis and Structure of Mono- and Binuclear (η6-p-Cymene)halo(salicylaldiminato)RuII Complexes

A series of mono- and binuclear (η6-p-cymene)chloro(sal-icylaldiminato)RuII complexes (1a,d, 2aa–ag,dc) were preparedby reaction of the μ-chloro dimer of (η6-p-cymene)RuII with thecorresponding sodium salts of salicylaldimines according to aliterature procedure.[15,17] Bromo (1b, 2ba, and 2bg) and iododerivatives (1c, 2ca, and 2cg) were obtained by ligand ex-change of the corresponding chloro complexes with NaBr andNaI, respectively.[3e,15] To allow comparison with the reactivitiesof halo complexes, the cationic 4-methylpyridine (4-MePy) com-plexes 3a,b and the PPh3 complex 3c were also prepared bytreating the corresponding chloro complex 1 with 4-MePy[5c]

and PPh3[5b] in the presence of AgPF6. Each of the novel com-

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plexes was characterized by 1H and 13C NMR, IR, and HRMSspectroscopic methods in conjunction with elemental analysis.The molecular structures of the mono- and binuclear complexeswere unequivocally established by X-ray diffraction (XRD) ofcrystals of 1a, 2aa, and 2dc. The crystallographic data and OR-TEP drawings of 1a, 2aa, and 2dc are presented in Table 1 andFigure 1. The crystal of 1a is composed of a racemic mixture ofRRu and SRu chiral centers. This results from pseudo-tetrahedralcoordination of the ligands, similarly to previous reports con-cerning N-hydroxyalkyl[15] and N-phenyl[17] analogues (Figure 1,a). Crystals of the binuclear complexes 2aa and 2dc were foundto be in the meso state, in which two metal centers with oppo-site chirality, R*Ru and S*Ru, are linked through polymethylenelinkers (Figure 1, b, c). It is noteworthy that each of the (p-cymene)(salicylaldiminato)RuII complexes 1a, 2aa, and 2dc andtheir reported analogues,[15,17] has a similar conformationaround the p-cymene ligand, such that the isopropyl group islocated close to the salicylaldiminato ligand for steric reasons.This conformation of complex 1a in the crystalline state wasalso observable in solution by 2D NMR spectroscopy, as dis-cussed in the next section.

Chirality Inversion of Mononuclear Complexes 1 inSolution State

Figure 2 presents the 1H NMR (upper and left vertical axes) and1H–1H NOESY spectra (500 MHz) of a solution of racemic 1a inCDCl3. In the 1H NMR spectrum, the aromatic protons Ha andHb in the p-cymene ligand of 1a appear separately at δ = 5.03and 5.39 ppm, respectively, attributable to the diastereotopicsignals of the chiral ruthenium species. Positive remote correla-tions are observed between the α protons of the N-butyl group(Hg and Hh) and Hc or Hd in the p-cymene ligand (correlationsA and B in Figure 2, a) as well as the expected correlations ofHd–Hf (iPr group, C), Hb–He (Me group, D), and Ha–He (E) in thep-cymene ligand. Correlations A and B indicate that the p-cym-ene ligand of 1a adopts a rotationally fixed conformation inCDCl3 in which the Hc (or Hd) protons are close to the α positionof the N-butyl group. The significant upfield shift of the Ha sig-nals in the 1H NMR spectrum strongly suggests that the Ha

protons in the less rotationally mobile p-cymene moiety receive

Figure 2. 1H NMR and 1H–1H NOESY spectra (500 MHz) of 1a in CDCl3 showing (a) positive and (b) negative correlations (293 K, mixing time: 0.800 s, numberof t1 increments: 512, number of t2 increments: 512, number of scans: 16). Signal and correlation assignments are shown in (a).


significant shielding due to the ring current from the spatiallyadjacent chloro functionality. Based on the A and B correlationsin these NOESY data and the specific upfield shift of the Ha

signals, we can conclude that the p-cymene ligand of 1a has afixed rotatory conformation in CDCl3, such that the portion ofthe p-cymene moiety around the Ha proton and the Me groupis spatially proximate to the chloro ligand for reasons related tosteric hindrance, similarly to the molecular structure deter-mined by XRD analysis (Figure 1). Most importantly, a strongnegative correlation, F, is observed between the Ha and Hb sig-nals of 1a in CDCl3 (Figure 2, b), which indicates that thesediastereotopic proton signals are exchanged rapidly on theNMR time scale. Given the reports of the chirality inversion of(η6-arene)(salicylaldiminato)RuII complexes,[5,15,16] the negativeNOESY correlation of Ha and Hb in the p-cymene ligand of 1acan be attributed to rapid chirality inversion of the rutheniumcenter in CDCl3.

Figure 3 (a) shows the variable-temperature 1H NMR spectra(400 MHz) of a 2.80 × 10–3 M solution of 1a in CDCl2CDCl2 inthe temperature range of 303–393 K. At 303 K, the Ha and Hb

protons are clearly split into two signals. These signals broadenwith increasing temperature and eventually coalesce into onebroad signal (δ = 5.23 ppm) at 373 K. The flipping rates of 1aupon chirality inversion in CDCl2CDCl2 were estimated to be9.20 s–1 (303 K), 1.50 × 101 s–1 (313 K), 2.85 × 101 s–1 (323 K),4.69 × 101 s–1 (333 K), 7.03 × 101 s–1 (343 K), 1.02 × 102 s–1

(353 K), 1.40 × 102 s–1 (363 K), 2.21 × 102 s–1 (373 K),3.38 × 102 s–1 (383 K), and 5.20 × 102 s–1 (393 K) by the line-shape method, based on the exchange of Ha and Hb signals(Figure 3, b)[14] using a gNMR simulation program.[18] The esti-mated rate constants (k) could be fitted by the Eyring relation-ship; a plot of ln (k/T) versus 1/T (R2 = 0.997, Figure 4) yieldedactivation parameters ΔH‡ and ΔS‡ of 40 ± 1 kJ mol–1 and–93 ± 2 J K–1 mol–1, respectively.

The consistency of the present line-shape method was veri-fied by using [(p-cymeme)(4-MePy){(S)-N-(1-phenylethyl)(salicyl-aldiminato)}RuII](PF6) (3b). The initial rate of chirality inversionof this complex (kobs = d[3b]/dt) was previously investigated bya direct method by evaluating the time-dependent changes inthe concentration of the semi-stable diastereomer in the pure(RRu,SC) form by 1H NMR spectroscopy.[5c] In the present study,

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Figure 3. (a) Experimental and (b) simulated 1H NMR spectra (400 MHz) show-ing the Ha and Hb signals of 1a in CDCl2CDCl2 (2.80 × 10–3 M) in the tempera-ture range 303–393 K. The rate constants used to fit the experimental lineshapes are indicated alongside each simulated spectrum.

Figure 4. Eyring plot for the flipping motion of 1a in CDCl2CDCl2. Kinetic datain the temperature range 303–393 K were obtained by the line-shape methodusing the Ha and Hb signals of the p-cymene ligand shown in Figure 3; slope:4.87(9)×103, intercept: –1.26(2)×10, R2 = 0.997.

the rates of chirality inversion of 3b in [D6]acetone were deter-mined in a similar manner by the line-shape method based onassessing the exchange of the Ha and Hb signals generated bythe major isomer, (RRu,SC)-3b. The forward flipping rates [k1:(RRu,SC) to (SRu,SC)] for the equilibrated diastereomeric transfor-mation between (RRu,SC)- and (SRu,SC)-3b between 303 and323 K were estimated to be 1.02 s–1 (303 K), 1.82 s–1 (308 K),3.29 s–1 (313 K), 5.27 s–1 (318 K), and 8.63 s–1 (323 K) based onthe resulting kex (kex = k1 + k–1)[14] and temperature-dependentvalues of the equilibrium constant K (K = k1/k–1; see Figure S19in the Supporting Information). The activation parameters ΔH‡

and ΔS‡ for the chirality inversion of (RRu,SC)- to (SRu,SC)-3b in[D6]acetone were calculated as 84 ± 2 kJ mol–1 and 33 ± 5 J K–

1·mol–1 (see Figure S20). The k1 value of 1.1 × 10–4 s–1 at 238 K(–35 °C) obtained from these activation parameters is in accordwith the reported value (τ1/2 = 80 min, k = 1.44 × 10–4 s–1) esti-mated from the epimerization of the pure diastereomer (RRu,SC)-3b,[5c] which indicates the validity of the present method.

The rates of chirality inversion at 303 K and the activationparameters for the chirality inversions of complexes 1–3 esti-mated by using the present line-shape method are presentedin Table 2. Given the fact that signal exchange of the cationicPPh3 complex 3c is not observed on the NMR time scale even


at higher temperatures, the rates of chirality inversion of themononuclear (p-cymene)(N-butyl-5-tert-butylsalicylaldimi-nato)RuII complexes with various anionic and neutral ligands X(1a–c and 3a,c: X = Cl, Br, I, 4-MePy, PPh3) in CDCl2CDCl2 at303 K increase in the order PPh3 < 4-MePy < Cl < Br < I (Table 2,entries 1–3 and 10, and Figures S1–S4, S17, and S18). The ap-proach used in this study therefore provides a convenient andcomplementary tool for evaluating the chirality inversion ofpseudo-tetrahedral η6-benzene complexes exhibiting fast inver-sion that cannot otherwise be evaluated by conventional directobservations of diastereomeric conversion. The chirality inver-sion rates of the polymethylene-linked bimetallic complexes2aa, 2ba, 2ca (n = 4) and 2ag, 2bg, 2cg (n = 12) in CDCl2CDCl2and their activation parameters (Table 2, entries 4–9 and Fig-ures S5–S16) are coincident with those of their monometallicanalogues 1a–c (Table 2, entries 1–3), which indicates that thetwo metal moieties undergo independent flipping motions inconjunction with chirality inversion of the metal center with nosignificant participation of neighboring groups.

Table 2. Activation parameters and exchange rates of the mono- and dinu-clear (p-cymene)(salicylaldiminato)ruthenium(II) complexes 1–3.[a]

Entry Complex Exchange rate (k) at 303 K ΔH‡ ΔS‡

[s–1] [kJ mol–1][b] [J mol–1 K–1][b]

1[c] 1a 9.20 40(1) –93(2)2[c] 1b 4.54 × 10 47(1) –59(3)3[c] 1c 1.15 × 102 47(1) –52(3)4[c] 2aa 8.77[d] 43(2) –86(5)5[c] 2ba 4.31 × 10[d] 46(3) –61(7)6[c] 2ca 1.08 × 102[d] 48(1) –47(3)7[c] 2ag 9.14 41(1) –92(3)8[c] 2bg 4.08 × 10 45(1) –65(3)9[c] 2cg 1.02 × 102 45(1) –60(3)10[e] 3a 1.80 76(1) 10(3)11[c] 3b (RRu,SC) to (SRu,SC): 2.80 × 10–1 66(3) –37(7)12[c] (SRu,SC) to (RRu,SC): 1.00 68(2) –22(8)13[c,f] (RRu,SC) to (SRu,SC): 1.02 84(2) 33(5)14[c,f] (SRu,SC) to (RRu,SC): 3.30 86(2) 49(5)

[a] Values were determined by 1H NMR analysis of solutions of 1, 2(2.8 × 10–3 M), or 3 (1.4 × 10–3 M) in CDCl2CDCl2 unless stated otherwise. [b]Estimated from the Eyring plots of the kinetic data (Figure 3, Figure 4, andFigures S1–S22). [c] Estimated by the line-shape method using the exchangeof the Ha and Hb signals of the p-cymene ligand. [d] Calculated from theactivation parameters. [e] Estimated by the line-shape method using the ex-change of Hc and Hd signals of the p-cymene ligand. [f ] These data wereacquired in [D6]acetone solution.

An enthalpy–entropy compensation plot[19] for the flippingmotions of 1–3 is shown in Figure 5. The halo complexes 1 and2 exhibit a significant correlation between the ΔH‡ and TΔS‡

values (T = 303 K), and all exhibit lower enthalpy and entropyvalues than the cationic complexes 3. Both the activation en-thalpy and entropy values of the halo complexes are seen toincrease in the order Cl (1a, 2aa, 2ag) < Br (1b, 2ba, 2bg) < I(1c, 2ca, 2cg). These tendencies can be attributed to the disso-ciative properties of the ligands during chirality inversion; thecomplexes undergo rate-determining dissociation of the ligand,chirality inversion of the resulting 16-electron complex, andsubsequent rebinding of the ligands from the outer sphere (seeFigure S23 in the Supporting Information). The higher ΔH‡ and

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ΔS‡ values of the iodo complexes compared with their chloroanalogues can be ascribed to the dissociative properties of thecorresponding iodo ligand. The rate-determining dissociationof the ligand requires higher energy levels to cleave thestronger Ru–X bond, and dynamic molecular alterations arenecessary for the dissociation of the ligand from the innersphere. The differing correlation shown by complexes 3 andthe much larger enthalpic and entropic contributions are alsoattributed to both the strong binding properties and extraordi-narily large size of the pyridine ligand.

Figure 5. Enthalpy–entropy compensation plots for the chirality inversions ofcomplexes 1–3. Kinetic studies were performed in CDCl2CDCl2 or [D6]acetone(in parentheses).

ConclusionsWe have successfully synthesized a series of mono- and binu-clear (p-cymene)(salicylaldiminato)RuII halide complexes (1 and2) bearing chiral Ru centers. The flipping motions of these com-plexes accompanying chirality inversion in the solution statewere examined based on kinetic studies using 1H NMR experi-ments in CDCl2CDCl2. The rates of chirality inversion for 1 and2 were readily estimated by means of the line-shape methodby assessing the exchange of the diastereotopic protons of thep-cymene ligands in a racemic mixture of the complexes. Theactivation enthalpy and entropy values obtained from thisstudy demonstrate that the flipping mobility of the halo com-plexes in solution is much more static than that of the cationicpyridine analogues 3, with reduced entropic and enthalpic con-tributions. The present method provides a convenient and com-plementary approach to the evaluation of chirality inversion inpseudo-tetrahedral η6-benzene complexes, because themethod can be performed on a racemic mixture of complexesbearing achiral salicylaldiminato ligands and is applicable tolabile halo complexes exhibiting fast inversion characteristics,which could not be estimated by the previous methods.

Experimental SectionGeneral: A series of mono- and dinuclear (η6-p-cymene)chloro(sali-cylaldiminato)ruthenium(II) complexes (1a: R1 = tBu, R2 = nBu; (SC)-1d: R1 = tBu, R2 = (S)-CHMePh); 2aa: R1 = tBu, n = 4; 2ab: R1 = tBu,n = 5; 2ac: R1 = tBu, n = 6; 2ad: R1 = tBu, n = 7; 2ae: R1 = tBu, n =


8; 2af: R1 = tBu, n = 9; 2ag: R1 = tBu, n = 12; 2dc: R1 = H, n = 6)were prepared by the reaction of di-μ-chloro-bis[(η6-p-cymene)-chloro]ruthenium(II) with the corresponding sodium salt of N-(p-tert-butylsalicylidene)butanamine for 1a (2 equiv.), N-(p-tert-butylsa-licylidene)-(S)-phenylethanamine for 1d (2 equiv.), N,N′-bis(p-tert-salicylidene)-1,n-alkanediamines for 2aa, 2ab, 2ac, 2ad, 2ae, 2af,2ag (1 equiv.), or N,N′-bis(salicylidene)-1,6-hexanediamine for 2dc(1 equiv.) according to the literature procedure.[15,17] Bromo com-plexes 1b (R1 = tBu, R2 = nBu), 2ba (R1 = tBu, n = 4), and 2bg (R1 =tBu, n = 12) and iodo complexes 1c (R1 = tBu, R2 = nBu), 2ca (R1 =tBu, n = 4), and 2cg (R1 = tBu, n = 12) were prepared by ligand-exchange reactions of the corresponding chloro analogues with ex-cess NaBr (for 1b, 2ba, and 2bg) or NaI (for 1c, 2ca, and 2cg).[3e,15]

Cationic complexes 3a (R1 = tBu, R2 = nBu, X = 4-methylpyridine),3b [R1 = H, R2 = (S)-CHMePh, X = 4-methylpyridine], and 3c (R1 =tBu, R2 = nBu, X = PPh3) were prepared by reaction of 1a or 1dwith 4-methylpyridine (1.5 equiv. for 3a and 3b)[5c] and reaction of1a with PPh3 (1.2 equiv. for 3c)[5b] in the presence of AgPF6

(1 equiv.). The complexes were recrystallized from hexane/ethylacetate (for 1) or hexane/dichloromethane (for 2 and 3) for kineticstudies, and their purities were confirmed by 1H NMR and elementalanalyses. Melting points were measured in glass capillary tubes witha Büchi B-545 melting-point apparatus. IR and far-IR spectra wereacquired with Bruker Equinox55 and Shimadzu IR Prestige-21 spec-trometers. 1H and 13C NMR spectra were recorded with Varian Unity-Inova 500, Varian Gemini 300, and Jeol JNM-AL-400 spectrometers.Assignments of the Ha–Hd signals of the p-cymene ligand and theH3–H6 signals of the salicylaldiminato ligands are shown inScheme 1. Elemental analyses were performed with a Perkin–Elmer2400II CHN elemental analyzer. Mass spectra were acquired by us-ing Jeol JMS-DX 303 and Bruker maXis 3G spectrometers.

1a (R1 = tBu, R2 = nBu, X = Cl): Brown solid (96 %), m.p. 200–201 °C. IR (KBr): ν̃ = 3053, 2959, 2869, 1621, 1530, 1478, 1419, 1392,1363, 1328, 1270, 1253, 1203, 1176, 1147, 879, 837, 823, 520 cm–1.1H NMR (CDCl3, 500 MHz): δ = 1.01 (t, J = 7.4 Hz, 3 H,-NCH2CH2CH2CH3), 1.14 [d, J = 7.0 Hz, 3 H, -C6H4CH(CH3)CH3], 1.21[s, 9 H, -C(CH3)3], 1.24 [d, J = 7.0 Hz, 3 H, -C6H4CH(CH3)CH3], 1.37–1.54 (m, 2 H, -NCH2CH2CH2-), 1.90–1.99 (m, 1 H, -NCH2CHH-), 1.99–2.09 (m, 1 H, -NCH2CHH-), 2.21 (s, 3 H, -C6H4CH3), 2.78 [qq, J = 7.0,7.0 Hz, 1 H, -C6H4CH(CH3)2], 4.03 (ddd, J = 14.1, 9.0, 7.0 Hz, 1 H,-NCHH-), 4.22 (ddd, J = 14.1, 9.4, 5.0 Hz, 1 H, -NCHH-), 5.04 (d, J =5.5 Hz, 1 H, Ha in p-cymene), 5.38 (d, J = 5.5 Hz, 1 H, Hb in p-cymene), 5.40 (s, 2 H, Hc, Hd in p-cymene), 6.81 (d, J = 2.6 Hz, 1 H,H6 in salicylaldimine), 6.89 (d, J = 9.0 Hz, 1 H, H3 in salicylaldimine),7.22 (dd, J = 9.0, 2.6 Hz, 1 H, H4 in salicylaldimine), 7.67 (s, 1 H, -N=CH-) ppm. 13C NMR (CDCl3, 125 MHz): δ = 163.8, 162.7, 136.1, 132.7,129.9, 121.6, 117.7, 101.3, 97.2, 85.8, 83.1, 82.1, 80.0, 69.3, 33.4, 33.3,31.2, 30.4, 22.7, 21.7, 20.4, 18.5, 13.9 ppm. HRMS (FAB): calcd. forC25H36NO102Ru [M – Cl]+ 468.1847; found 468.1852. C25H36ClNORu(503.09): calcd. C 59.69, H 7.21, N 2.78; found C, 59.68; H, 7.37; N,2.70.

1b (R1 = tBu, R2 = nBu, X = Br): Brown solid (99 %), m.p. 170 °C(decomp.). IR (KBr): ν̃ = 3053, 2960, 2870, 1621, 1530, 1478, 1392,1364, 1328, 1270, 1253, 1211, 1176, 1147, 879, 838, 823, 610 cm–1.1H NMR (CDCl3, 500 MHz): δ = 1.03 (t, J = 7.4 Hz, 3 H,-NCH2CH2CH2CH3), 1.13 [d, J = 7.1 Hz, 3 H, -C6H4CH(CH3)CH3], 1.21[s, 9 H, -C(CH3)3], 1.25 [d, J = 7.1 Hz, 3 H, -C6H4CH(CH3)CH3], 1.39–1.53 (m, 2 H, -NCH2CH2CH2-), 1.88–1.99 (m, 1 H, -NCH2CHH-), 1.99–2.09 (m, 1 H, -NCH2CHH-), 2.26 (s, 3 H, -C6H4CH3), 2.83 [qq, J = 7.1,7.1 Hz, 1 H, -C6H4CH(CH3)2], 4.05 (ddd, J = 14.1, 9.0, 7.0 Hz, 1 H,-NCHH-), 4.20 (ddd, J = 14.1, 9.4, 5.0 Hz, 1 H, -NCHH-), 5.07 (d, J =5.4 Hz, 1 H), 5.41 (d, J = 5.4 Hz, 1 H), 5.43 (d, J = 5.4 Hz, 1 H), 5.50(d, J = 5.4 Hz, 1 H), 6.82 (d, J = 2.6 Hz, 1 H, H6 in salicylaldimine),

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6.89 (d, J = 8.8 Hz, 1 H, H3 in salicylaldimine), 7.23 (dd, J = 8.8,2.6 Hz, 1 H, H4 in salicylaldimine), 7.64 (s, 1 H, -N=CH-) ppm. HRMS(FAB): calcd. for C25H36NO79Br102Ru [M]+ 547.1024; found 547.1023.

1c (R1 = tBu, R2 = nBu, X = I): Brown solid (99 %), m.p. 180 °C(decomp.). IR (KBr): ν̃ = 2955, 2869, 1621, 1531, 1477, 1391, 1328,1253, 1178, 1052, 873, 822, 731, 610, 518 cm–1. 1H NMR (CDCl3,300 MHz): δ = 1.03 (t, J = 7.5 Hz, 3 H, -NCH2CH2CH2CH3), 1.16 [br.s, 3 H, -C6H4CH(CH3)CH3], 1.21 [s, 9 H, -C(CH3)3], 1.28 [br. s, 3 H,-C6H4CH(CH3)CH3], 1.39–1.54 (m, 2 H, -NCH2CH2CH2-), 1.85–2.10 (m,2 H, -NCH2CH2-), 2.35 (s, 3 H, -C6H4CH3), 2.90 [qq, J = 6.7, 6.7 Hz, 1H, -C6H4CH(CH3)2], 4.03 (br. s, 1 H, -NCHH-), 4.13 (br. s, 1 H,-NCHH-), 5.02 (br. s, 1 H, Ha in p-cymene), 5.29 (br. s, 1 H, Hc in p-cymene), 5.51 (br. s, 1 H, Hd in p-cymene), 5.62 (br. s, 1 H, Hb in p-cymene), 6.79 (d, J = 2.6 Hz, 1 H, H6 in salicylaldimine), 6.84 (d, J =8.9 Hz, 1 H, H3 in salicylaldimine), 7.21 (dd, J = 8.9, 2.6 Hz, 1 H, H4

in salicylaldimine), 7.56 (s, 1 H, -N=CH-) ppm. HRMS (FAB): calcd. forC25H36NOI102Ru [M – I]+ 468.1840; found 468.1839.

2aa (R1 = tBu, X = Cl, n = 4): Brown solid (70 %), m.p. 250 °C(decomp.). IR (KBr): ν̃ = 2959, 2868, 1627, 1537, 1484, 1397, 1361,1322, 1272, 1258, 1202, 1177, 1145, 1061, 854, 839, 813, 610,543 cm–1. Far-IR (CsI): ν̃ = 273, 253 cm–1. 1H NMR (CDCl3, 500 MHz;major/minor = 67:33): δ = 1.07 [d, J = 7.0 Hz, 0.33 × 6 H,-C6H4CH(CH3)CH3 (minor)], 1.10 [d, J = 7.0 Hz, 0.67 × 6 H,-C6H4CH(CH3)CH3 (major)], 1.18 [d, J = 7.0 Hz, 0.67 × 6 H,-C6H4CH(CH3)CH3 (major)], 1.20 [s, 0.33 × 18 H, -C(CH3)3 (minor)],1.21 [s, 0.67 × 18 H, -C(CH3)3 (major)], 1.23 [d, J = 7.0 Hz, 0.33 × 6 H,-C6H4CH(CH3)CH3 (minor)], 1.81–1.94 [m, 4 H, -NCH2CH2- (major andminor)], 2.03 [s, 0.67 × 6 H, -C6H4CH3 (major)], 2.21 [s, 0.33 × 6 H,-C6H4CH3 (minor)], 2.69 [qq, J = 7.0, 7.0 Hz, 0.67 × 2 H,-C6H4CH(CH3)2 (major)], 2.72 [qq, J = 7.0, 7.0 Hz, 0.33 × 2 H,-C6H4CH(CH3)2 (minor)], 3.83–3.94 [m, 0.67 × 2 H, -NCH2- (major)],4.00–4.11 [m, 0.33 × 2 H, -NCH2- (minor)], 4.30–4.37 [m, 0.33 × 2 H,-NCH2- (minor)], 4.47 [dm, J = 12.1 Hz, 0.67 × 2 H, -NCH2- (major)],5.07 [d, J = 5.5 Hz, 0.67 × 2 H, Ha in p-cymene (major)], 5.14 [d, J =5.5 Hz, 0.33 × 2 H, Ha in p-cymene (minor)], 5.33 [d, J = 5.5 Hz,0.67 × 2 H, Hb in p-cymene (major)], 5.35–5.41 [m, 4 H, Hb (minor),Hc (major and minor), and Hd (major) in p-cymene], 5.43 [d, J =5.5 Hz, 0.33 × 2 H, Hd in p-cymene (minor)], 6.84 [d, J = 2.3 Hz,0.33 × 2 H, H6 in salicylaldimine (minor)], 6.885 [d, J = 2.3 Hz,0.67 × 2 H, H6 in salicylaldimine (major)], 6.887 [d, J = 8.9 Hz, 2 H,H3 in salicylaldimine (major and minor)], 7.23 [dd, J = 8.9, 2.3 Hz, 2H, H4 in salicylaldimine (major and minor)], 7.68 [s, 0.33 × 2 H, -N=CH- (minor)], 7.72 [s, 0.67 × 2 H, -N=CH- (major)] ppm. 13C NMR(CDCl3, 125 MHz): δ = 164.1 (major), 164.0 (minor), 163.1 (minor),162.8 (major), 136.3 (minor), 136.0 (major), 132.8 (major and minor),130.5 (major), 130.0 (minor), 121.8 (minor), 121.5 (major), 118.0 (mi-nor), 117.2 (major), 101.1 (minor), 99.9 (major), 98.8 (major), 97.5(minor), 87.5 (major), 85.9 (minor), 82.9 (minor), 82.6 (major), 81.9(minor), 81.1 (major), 80.8 (major), 80.3 (minor), 70.3 (major), 69.2(minor), 33.4 (major and minor), 31.3 (major and minor), 30.5 (majorand minor), 22.9 (major), 22.7 (minor), 21.7 (major and minor), 18.6(minor), 18.5 (major) ppm. C46H62Cl2N2O2Ru2 (948.05): calcd. C58.28, H 6.59, N 2.95; found C 58.02, H 6.51, N 3.18.

2ab (R1 = tBu, X = Cl, n = 5): Brown solid (32 %), m.p. 151–152 °C.IR (KBr): ν̃ = 2961, 2867, 1621, 1533, 1480, 1393, 1363, 1323, 1257,1213, 1179, 1148, 1088, 1052, 878, 826, 803, 797, 612 cm–1. Far-IR(CsI): ν̃ = 274, 244 cm–1. 1H NMR (CDCl3, 500 MHz; major/minor =41:59): δ = 1.10 [d, J = 7.0 Hz, 0.59 × 6 H, -C6H4CH(CH3)CH3 (major)],1.11 [d, J = 7.0 Hz, 0.41 × 6 H, -C6H4CH(CH3)CH3 (minor)], 1.17–1.24[m, 8 H, -C6H4CH(CH3)CH3 (major and minor), N(CH2)2CHH- (majorand minor)], 1.20 [s, 0.59 × 18 H, -C(CH3)3 (major)], 1.22 [s, 0.41 × 18H, -C(CH3)3 (minor)], 1.99–2.06 [m, 1 H, -NCH2CHH- (major and mi-


nor)], 2.06–2.15 [m, 1 H, -NCH2CHH- (major and minor)], 2.19 [s,0.41 × 6 H, -C6H4CH3 (minor)], 2.30 [s, 0.59 × 6 H, -C6H4CH3 (major)],2.71 [qq, J = 7.0, 7.0 Hz, 0.41 × 2 H, -CH(CH3)2 (minor)], 2.74 [qq, J =7.0, 7.0 Hz, 2 H, -C6H4CH(CH3)2 (major)], 3.88 [ddd, J = 12.0, 8.0,7.0 Hz, 0.59 × 2 H, -NCH2- (major)], 4.00 [ddd, J = 12.0, 8.0, 8.0 Hz,0.41 × 2 H, -NCH2- (minor)], 4.35 [ddd, J = 12.0, 8.0, 4.9 Hz, 0.41 × 2H, -NCH2- (minor)], 4.40 [ddd, J = 12.0, 7.0, 5.0 Hz, 0.59 × 2 H, -NCH2-(major)], 5.05 [d, J = 5.5 Hz, 0.41 × 2 H, Ha in p-cymene (minor)],5.10 [d, J = 5.5 Hz, 0.59 × 2 H, Ha in p-cymene (major)], 5.34–5.50[m, 6 H, Hb, Hc, Hd in p-cymene (major and minor)], 6.80 [d, J =2.5 Hz, 0.59 × 2 H, H6 in salicylaldimine (major)], 6.85 [d, J = 2.0 Hz,0.41 × 2 H, H6 in salicylaldimine (minor)], 6.89 [d, J = 8.8 Hz, 0.59 × 2H, H3 in salicylaldimine (major)], 6.90 [d, J = 8.8 Hz, 0.41 × 2 H, H3

in salicylaldimine (minor)], 7.23 [dm, J = 8.8 Hz, 2 H, H4 in salicylald-imine (major and minor)], 7.66 [s, 0.59 × 2 H, -N=CH- (major)], 7.70[s, 0.41 × 2 H, -N=CH- (minor)] ppm. HRMS (FAB): calcd. forC47H64N2O2

35Cl102Ru2 [M – Cl]+ 927.2744; found 927.2758.

2ac (R1 = tBu, X = Cl, n = 6): Brown solid (84 %), m.p. 235 °C(decomp.). IR (KBr): ν̃ = 3050, 2960, 2874, 1615, 1538, 1470, 1408,1374, 1330, 1200, 1150, 1026, 910, 866, 762 cm–1. Far-IR (CsI): ν̃ =275, 251 cm–1. 1H NMR (CDCl3, 500 MHz; major/minor = 58:42): δ =1.09 [d, J = 7.0 Hz, 6 H × 0.58, -C6H4CH(CH3)CH3 (major)], 1.11 [d,J = 7.0 Hz, 6 H × 0.42, -C6H4CH(CH3)CH3 (minor)], 1.16–1.26 [m, 6 H,-C6H4CH(CH3)CH3 (major and minor)], 1.20 [s, 18 H, -C(CH3)3 (majorand minor)], 1.30–1.62 [m, 2 H, -NCH2CH2- (major and minor)], 1.91–2.11 [m, 2 H, -NCH2CH2CH2- (major and minor)], 2.15 [s, 0.58 × 6 H,-C6H4CH3 (major)], 2.22 [s, 6 H, -C6H4CH3 (minor)], 2.73 [qq, J = 7.0,7.0 Hz, 2 H, -C6H4CH(CH3)2 (major and minor)], 3.91–4.04 [m, 2 H,-NCH2- (major and minor)], 4.25–4.39 [m, 2 H, -NCH2- (major andminor)], 5.01 [d, J = 5.5 Hz, 0.58 × 2 H, Ha in p-cymene (major)], 5.06[d, J = 5.5 Hz, 0.42 × 2 H, Ha in p-cymene (minor)], 5.34–5.45 [m, 6H, Hb, Hc, Hd in p-cymene (major and minor)], 6.83 [d, J = 2.4 Hz, 2H, H6 in salicylaldimine (major and minor)], 6.88 [d, J = 8.6 Hz,0.58 × 2 H, H3 in salicylaldimine (major)], 6.89 [d, J = 8.6 Hz, 0.42 × 2H, H3 in salicylaldimine (minor)], 7.21 [dm, J = 8.6 Hz, 2 H, H4 insalicylaldimine (major and minor)], 7.67 [s, 0.42 × 2 H, -N=CH- (mi-nor)], 7.70 [s, 0.58 × 2 H, -N=CH- (major)] ppm. HRMS (FAB): calcd.for C48H66N2O2

35Cl102Ru2 [M – Cl]+ 941.2900; found 941.2892.

2ad (R1 = tBu, X = Cl, n = 7): Brown solid (66 %), m.p. 181 °C(decomp.). IR (KBr): ν̃ = 3049, 2959, 2865, 1622, 1532, 1479, 1392,1363, 1326, 1270, 1255, 1211, 1179, 1146, 1056, 1033, 859, 826 cm–

1. Far-IR (CsI): ν̃ = 274, 250 cm–1. 1H NMR (CDCl3, 500 MHz; major/minor = 52:48): δ = 1.12 [d, J = 6.2 Hz, 6 H, -C6H4CH(CH3)CH3 (majorand minor)], 1.18–1.25 [m, 6 H, -C6H4CH(CH3)CH3 (major and mi-nor)], 1.21 [s, 18 H, -C(CH3)3 (major and minor)], 1.32–1.40 [m, 2 H,-N(CH2)3CH- (major and minor)], 1.42–1.55 [m, 4 H, -N(CH2)2CH2-(major and minor)], 1.91–2.07 [m, 4 H, -NCH2CH2- (major and mi-nor)], 2.19 [s, 0.48 × 6 H, -C6H4CH3 (minor)], 2.22 [s, 0.52 × 6 H,-C6H4CH3 (major)], 2.75 [qq, J = 7.0, 7.0 Hz, 2 H, -C6H4CH(CH3)2 (ma-jor and minor)], 3.92–4.02 [m, 2 H, -NCH2- (major and minor)], 4.29[ddd, J = 13.0, 6.5, 6.5 Hz, 2 H, -NCH2- (major and minor)], 5.03 [d,J = 6.4 Hz, 0.48 × 2 H, Ha in p-cymene (minor)], 5.05 [d, J = 6.4 Hz,0.52 × 2 H, Ha in p-cymene (major)], 5.36–5.44 [m, 6 H, Hb, Hc, Hd inp-cymene (major and minor)], 6.82 [d, J = 2.5 Hz, 2 H, H6 in salicyl-aldimine (major and minor)], 6.88 [d, J = 8.9 Hz, 2 H, H3 in salicylald-imine (major and minor)], 7.21 [dd, J = 8.9, 2.5 Hz, 2 H, H4 in salicyl-aldimine (major and minor)], 7.67 [s, 0.48 × 2 H, -N=CH- (minor)],7.68 [s, 0.52 × 2 H, -N=CH- (major)] ppm. HRMS (FAB): calcd. forC49H68N2O2

35Cl102Ru2 [M – Cl]+ 955.3056; found 955.3061.

2ae (R1 = tBu, X = Cl, n = 8): Brown solid (89 %), m.p. 216 °C(decomp.). IR (KBr): ν̃ = 3017, 2960, 2866, 1622, 1530, 1480, 1393,1364, 1329, 1271, 1208, 1177, 1145, 882, 824 cm–1. Far-IR (CsI): ν̃ =

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275, 250 cm–1. 1H NMR (CDCl3, 270 MHz; major/minor = 51:49): δ =1.13 [d, J = 6.8 Hz, 6 H, -C6H4CH(CH3)CH3 (major and minor)], 1.21[s, 18 H, -C(CH3)3 (major and minor)], 1.23 [d, J = 6.8 Hz, 0.51 × 6 H,-C6H4CH(CH3)CH3 (major)], 1.24 [d, J = 6.8 Hz, 6 H, -C6H4CH(CH3)2

(minor)], 1.35–1.52 [m, 8 H, -N(CH2)2(CH2)2- (major and minor)],1.90–2.10 [m, 4 H, -NCH2CH2- (major and minor)], 2.20 [s, 0.51 × 6H, -C6H4CH3 (major)], 2.22 [s, 0.49 × 6 H, -C6H4CH3 (minor)], 2.76 [qq,J = 6.8, 6.8 Hz, 2 H, -C6H4CH(CH3)2 (major and minor)], 3.99 [ddd,J = 13.0, 8.0, 7.0 Hz, 2 H, -NCH2- (major and minor)], 4.27 [ddd, J =13.0, 7.0, 6.0 Hz, 2 H, -NCH2- (major and minor)], 5.03 [d, J = 5.6 Hz,0.51 × 2 H, Ha in p-cymene (major)], 5.05 [d, J = 5.6 Hz, 0.49 × 2 H,Ha in p-cymene (minor)], 5.38 [d, J = 5.6 Hz, 2 H, Hb in p-cymene(major and minor)], 5.39–5.42 [m, 4 H, Hc, Hd in p-cymene (majorand minor)], 6.81–6.84 [m, 2 H, H6 in salicylaldimine (major andminor)], 6.89 [d, J = 8.8 Hz, 2 H, H3 in salicylaldimine (major andminor)], 7.22 [dd, J = 8.8, 2.7 Hz, 2 H, H4 in salicylaldimine (majorand minor)], 7.675 [s, 0.51 × 2 H, -N=CH- (major)], 7.683 [s, 0.49 × 2H, -N=CH- (minor)] ppm. 13C NMR (CDCl3, 68 MHz): δ = 21.7, 22.8,27.1, 29.2, 30.5, 31.2, 31.3, 33.5, 69.8, 80.1, 82.1, 83.2, 86.2, 97.4,101.2, 117.7, 121.6, 130.0, 132.8, 136.2, 162.8, 163.7 ppm. HRMS(FAB): calcd. for C50H70N2O2

35Cl102Ru2 [M – Cl]+ 969.3212; found969.3218.

2af (R1 = tBu, X = Cl, n = 9): Black solid (24 %), m.p. 183 °C (de-comp.). IR (KBr): ν̃ = 2959, 2925, 2862, 1621, 1533, 1480, 1421, 1392,1362, 1325, 1270, 1255, 1179, 1146, 1055, 826 cm–1. Far-IR (CsI): ν̃ =258, 234 cm–1. 1H NMR (CDCl3, 500 MHz; diastereomer ratio: 50:50):δ = 1.14 [d, J = 6.8 Hz, 6 H, -C6H4CH(CH3)CH3], 1.21 [s, 18 H,-C(CH3)3], 1.24 [d, J = 6.8 Hz, 6 H, -C6H4CH(CH3)CH3], 1.30–1.50 [m,10 H, -N(CH2)2(CH2)2CHH-], 1.89–2.10 (m, 4 H, -NCH2CH2-), 2.198 (s,0.50 × 6 H, -C6H4CH3), 2.220 (s, 0.50 × 6 H, -C6H4CH3), 2.77 [qq, J =6.8, 6.8 Hz, 2 H, -C6H4CH(CH3)2], 4.00 (ddd, J = 13.0, 8.0, 7.0 Hz, 2 H,-NCH2-), 4.25 (ddd, J = 13.0, 7.0, 6.0 Hz, 2 H, -NCH2-), 5.01–5.06 (m,2 H, Ha in p-cymene), 5.38 (d, J = 5.7 Hz, 2 H, Hb in p-cymene),5.39–5.42 (m, 4 H, Hc, Hd in p-cymene), 6.82 (d, J = 2.5 Hz, 2 H, H6

in salicylaldimine), 6.88 (d, J = 8.9 Hz, 2 H, H3 in salicylaldimine),7.22 (dd, J = 8.9, 2.5 Hz, 2 H, H4 in salicylaldimine), 7.67 (s, 2 H, -N=CH-) ppm. HRMS (FAB): calcd. for C51H72N2O2

35Cl102Ru2 [M – Cl]+

983.3369; found 983.3364.

2ag (R1 = tBu, X = Cl, n = 12): Brown solid (40 %), m.p. 121 °C. IR(KBr): ν̃ = 3044, 2959, 2925, 2855, 1622, 1532, 1479, 1392, 1363,1327, 1255, 1211, 1179, 1145, 858, 837, 826 cm–1. Far-IR (CsI): ν̃ =274 cm–1. 1H NMR (CDCl3, 500 MHz): δ = 1.13 [d, J = 6.9 Hz, 6 H,-C6H4CH(CH3)CH3], 1.20 [s, 18 H, -C(CH3)3], 1.24 [d, J = 6.9 Hz, 6 H,-C6H4CH(CH3)CH3], 1.26–1.48 [m, 16 H, -N(CH2)2(CH2)4-], 1.88–2.00(m, 2 H, -NCH2CHH-), 2.00–2.12 (m, 2 H, -NCH2CHH-), 2.21 (s, 6 H,-C6H4CH3), 2.77 [qq, J = 6.9, 6.9 Hz, 2 H, -C6H4CH(CH3)2], 4.01 (ddd,J = 13.0, 9.0, 7.0 Hz, 2 H, -NCH2-), 4.23 (ddd, J = 13.0, 9.0, 5.0 Hz, 2H, -NCH2-), 5.04 (d, J = 5.5 Hz, 2 H, Ha in p-cymene), 5.38 (d, J =5.5 Hz, 2 H, Hb in p-cymene), 5.30–5.43 (m, 4 H, Hc, Hd in p-cymene),6.82 (d, J = 2.5 Hz, 2 H, H6 in salicylaldimine), 6.89 (d, J = 8.8 Hz, 2H, H3 in salicylaldimine), 7.22 (dd, J = 8.8, 2.5 Hz, 2 H, H4 in salicylald-imine), 7.68 (s, 2 H, -N=CH-) ppm. HRMS (FAB): calcd. forC54H78N2O2

35Cl102Ru2 [M – Cl]+ 1025.3838; found 1025.3846.

2ba (R1 = tBu, X = Br, n = 4): Orange solid (91 %), m.p. 250 °C(decomp.). IR (KBr): ν̃ = 3042, 2959, 2867, 1622, 1532, 1480, 1394,1362, 1324, 1270, 1255, 1177, 1146, 1057, 1036, 856, 838, 826 cm–

1. 1H NMR (CDCl3, 500 MHz; major/minor = 55:45): δ = 1.12 [br. s, 6H, -C6H4CH(CH3)CH3 (major and minor)], 1.18–1.25 [m, 6 H,-C6H4CH(CH3)CH3 (major and minor)], 1.21 [s, 18 H, -C(CH3)3 (majoramd minor)], 1.87–2.11 [m, 4 H, -NCH2CH2- (major and minor)], 2.15[s, 0.55 × 6 H, -C6H4CH3 (major)], 2.28 [s, 0.45 × 6 H, -C6H4CH3 (mi-nor)], 2.77 [br. s, 2 H, -C6H4CH(CH3)2 (major and minor)], 3.83–4.00


[m, 0.55 × 2 H, -NCH2- (major)], 3.97–4.15 [m, 0.45 × 2 H, -NCH2-(minor)], 4.25–4.42 [m, 0.45 × 2 H, -NCH2- (minor)], 4.40–4.51 [m,0.55 × 2 H, -NCH2- (major)], 5.04 [br. s, 0.55 × 2 H, Ha in p-cymene(major)], 5.09 [br. s, 0.45 × 2 H, Ha in p-cymene (minor)], 5.30–5.50[m, 6 H, Hb, Hc, Hd in p-cymene (major and minor)], 6.81–6.92 [br.s, 2 H, H6 in salicylaldimine (major and minor)], 6.88 [d, J = 8.8 Hz,2 H, H3 in salicylaldimine (major and minor)], 7.23 [dd, J = 8.8,2.6 Hz, 2 H, H4 in salicylaldimine (major and minor)], 7.67 [s, 2 H,-N=CH- (major and minor)] ppm. HRMS (FAB): calcd. forC46H62N2O2

79Br102Ru2 [M – Br]+ 957.2081; found 957.2083.

2ca (R1 = tBu, X = I, n = 4): Brown solid (70 %), m.p. 250 °C (de-comp.). IR (KBr): ν̃ = 3041, 2961, 2868, 1620, 1531, 1478, 1395, 1363,1327, 1271, 1256, 1175, 1146, 1058, 866, 839, 824, 612 cm–1. 1HNMR (CDCl3, 500 MHz; major/minor = 55:45): δ = 1.09–1.17 [m, 6 H,-C6H4CH(CH3)CH3 (major and minor)], 1.17–1.29 [m, 6 H,-C6H4CH(CH3)CH3 (major and minor)], 1.22 [s, 18 H, -C(CH3)3 (majorand minor)], 1.98–2.24 [m, 4 H, -NCH2CH2- (major and minor)], 2.35[s, 6 H, -C6H4CH3 (major and minor)], 2.85 [br. s, 2 H, -C6H4CH- (majorand minor)], 3.82–4.07 [m, 2 H, -NCH2- (major and minor)], 4.15–4.33 [m, 0.55 × 2 H, -NCH2- (major)], 4.31–4.45 [m, 0.45 × 2 H, -NCH2-(minor)], 5.10 [br. s, 2 H, Ha in p-cymene (major and minor)], 5.35[br. s, 2 H, Hc in p-cymene (major and minor)], 5.43–5.65 [m, 4 H,Hb, Hd in p-cymene (major and minor)], 6.84 [d, J = 8.8 Hz, 2 H, H3

in salicylaldimine (major and minor)], 6.89 [d, J = 2.5 Hz, 2 H, H6 insalicylaldimine (major and minor)], 7.22 [dd, J = 8.8, 2.5 Hz, 2 H, H4

in salicylaldimine (major and minor)], 7.62 [s, 2 H, -N=CH- (majorand minor)] ppm. HRMS (FAB): calcd. for C46H62N2O2I102Ru2 [M – I]+

1005.1943; found 1005.1956.

2bg (R1 = tBu, X = Br, n = 12): Brown solid (25 %), m.p. 150 °C. IR(KBr): ν̃ = 2958, 2925, 2850, 1617, 1559, 1472, 1323, 1252, 1178,1046, 821 cm–1. 1H NMR (CDCl3, 500 MHz): δ = 1.14 [d, J = 6.4 Hz,6 H, -C6H4CH(CH3)CH3], 1.20 [s, 18 H, -C(CH3)3], 1.26 [d, J = 6.4 Hz,6 H, -C6H4CH(CH3)CH3], 1.28–1.48 [m, 16 H, -N(CH2)2(CH2)4-], 1.90–2.00 (m, 2 H, -NCH2CHH-), 2.00–2.11 (m, 2 H, -NCH2CHH-), 2.27 (s, 6H, -C6H4CH3), 2.82 [qq, J = 7.0, 7.0 Hz, 2 H, -C6H4CH(CH3)2], 4.03(ddd, J = 13.0, 9.0, 7.0 Hz, 2 H, -NCH2-), 4.21 (ddd, J = 13.0, 9.0,5.0 Hz, 2 H, -NCH2-), 5.04 (d, J = 5.0 Hz, 2 H, Ha in p-cymene), 5.42(d, J = 5.0 Hz, 2 H, Hb in p-cymene), 5.33–5.53 (m, 4 H, Hc and Hd

in p-cymene), 6.81 (d, J = 2.7 Hz, 2 H, H6 in salicylaldimine), 6.88 (d,J = 8.9 Hz, 2 H, H3 in salicylaldimine), 7.22 (dd, J = 8.9, 2.7 Hz, 2 H,H4 in salicylaldimine), 7.64 (s, 2 H, -N=CH-) ppm. 13C NMR (CDCl3,125 MHz): δ = 19.1, 21.8, 22.7, 27.2, 29.4, 29.5, 30.6, 31.3, 31.4, 33.4,69.9, 79.8, 82.7, 83.5, 85.3, 96.4, 102.4, 117.9, 121.6, 129.9, 132.8,136.2, 162.6, 163.9 ppm. HRMS (FAB): calcd. forC54H78N2O2

79Br102Ru2 [M – Br]+ 1069.3334; found 1069.3339.

2cg (R1 = tBu, X = I, n = 12): Black solid (95 %), m.p. 149 °C. IR(KBr): ν̃ = 2971, 2894, 1635, 1559, 1472, 1394, 1256, 1052, 879 cm–

1. 1H NMR (CDCl3, 500 MHz): δ = 1.11–1.18 [m, 6 H,-C6H4CH(CH3)CH3], 1.21 [s, 18 H, -C(CH3)3], 1.23–1.29 [m, 6 H,-C6H4CH(CH3)CH3], 1.30–1.48 [m, 16 H, -N(CH2)2(CH2)4-], 1.88–2.00(m, 2 H, -NCH2CHH-), 2.00–2.12 (m, 2 H, -NCH2CHH-), 2.35 (s, 6 H,-C6H4CH3), 2.89 [qq, J = 7.0, 7.0 Hz, 2 H, -C6H4CH(CH3)2], 3.94–4.08(m, J = 7.0 Hz, 2 H, -NCH2-), 4.09–4.21 (m, 2 H, -NCH2-), 4.97–5.05(m, 2 H, Ha in p-cymene), 5.24–5.32 (m, 2 H, Hb in p-cymene), 5.48–5.67 (m, 4 H, Hc, Hd in p-cymene), 6.80 (d, J = 2.5 Hz, 2 H, H6 insalicylaldimine), 6.84 (d, J = 8.9 Hz, 2 H, H3 in salicylaldimine), 7.21(dd, J = 8.9, 2.5 Hz, 2 H, H4 in salicylaldimine), 7.56 (s, 2 H, -N=CH-) ppm. 13C NMR (CDCl3, 125 MHz): δ = 20.1, 21.9, 22.5, 27.1, 29.4,29.5, 30.8, 31.3, 31.5, 33.4, 70.7, 79.9, 83.3, 83.6, 84.1, 95.6, 104.5,118.6, 121.6, 129.8, 132.9, 136.1, 162.5, 164.2 ppm. HRMS (FAB):calcd. for C54H78N2O2I102Ru2 [M – I]+ 1117.3195; found 1117.3185.

Full Paper

2dc (R1 = H, X = Cl, n = 6): Orange solid (74 %), m.p. 215 °C (de-comp.). IR (KBr): ν̃ = 2960, 2901, 2874, 2846, 1615, 1538, 1470, 1450,1408, 1374, 1356, 1330, 1200, 1150, 1026, 910, 866, 762, 736,521 cm–1. 1H NMR (CDCl3, 500 MHz; major/minor = 59:41): δ = 1.09[d, J = 6.9 Hz, 0.59 × 6 H, -C6H4CH(CH3)CH3 (major)], 1.11 [d, J =6.9 Hz, 0.41 × 6 H, -C6H4CH(CH3)CH3 (minor)], 1.20 [d, J = 6.9 Hz,0.59 × 6 H, -C6H4CH(CH3)CH3 (major)], 1.23 [d, J = 6.9 Hz, 0.41 × 6H, -C6H4CH(CH3)CH3 (minor)], 1.29–1.44 [m, 2 H, -N(CH2)2CHH- (ma-jor and minor)], 1.48–1.59 [m, 2 H, -N(CH2)2CHH- (major and minor)],1.89–2.09 [m, 4 H, -NCH2CH2- (major and minor)], 2.14 [s, 0.59 × 6H, -C6H4CH3 (major)], 2.22 [s, 0.41 × 6 H, -C6H4CH3 (minor)], 2.73 [qq,J = 6.9, 6.9 Hz, 2 H, -C6H4CH(CH3)2 (major and minor)], 3.92–4.04[m, 2 H, -NCH2- (major and minor)], 4.25–4.36 [m, 2 H, -NCH2- (majorand minor)], 5.00 [d, J = 5.5 Hz, 0.59 × 2 H, Ha in p-cymene (major)],5.07 [d, J = 5.5 Hz, 0.41 × 2 H, Ha in p-cymene (minor)], 5.37 [d, J =5.5 Hz, 2 H, Hb in p-cymene (major and minor)], 5.38–5.44 [m, 4 H,Hc, Hd in p-cymene (major and minor)], 6.40 [dd, J = 7.5, 7.5 Hz, 2H, H5 in salicylaldimine (major and minor)], 6.88–6.97 [m, 4 H, H3,H6 in salicylaldimine (major and minor)], 7.14 [dd, J = 7.5, 7.5 Hz, 2H, H4 in salicylaldimine (major and minor)], 7.66 [s, 0.41 × 2 H, -N=CH- (minor)], 7.72 [s, 0.59 × 2 H, -N=CH- (major)] ppm. MS (ESI):m/z = 829.6 [M – Cl]+. C40H50Cl2N2O2Ru2 (863.89): calcd. C 55.61, H5.83, N 3.24; found C 55.55, H 5.86, N 3.39.

3a (R1 = tBu, R2 = nBu, X = 4-methylpyridine): Brown solid (99 %),m.p. 79–80 °C. IR (KBr): ν̃ = 2960, 2872, 1616, 1533, 1477, 1395,1363, 1319, 1259, 1211, 1180, 1151, 1111, 1064, 1031, 831, 738, 669,613 cm–1. 1H NMR (CDCl3, 300 MHz): δ = 0.93 (t, J = 7.1 Hz, 3 H,-NCH2CH2CH2CH3), 1.15 [d, J = 6.9 Hz, 6 H, -C6H4CH(CH3)2], 1.21 [s,9 H, -C(CH3)3], 1.34–1.51 (m, 2 H, -NCH2CH2CH2-), 1.57–1.70 (m, 2 H,-NCH2CH2-), 1.92 (s, 3 H, C6H4N-4-CH3), 2.39 (s, 3 H, -C6H4CH3), 2.64[sept, J = 6.9 Hz, 1 H, -C6H4CH(CH3)2], 4.18 (ddd, J = 13.6, 10.0,5.0 Hz, 1 H, -NCHH-), 4.34 (ddd, J = 13.6, 9.8, 5.8 Hz, 1 H, -NCHH-),5.38 (d, J = 6.4 Hz, 1 H, Ha in p-cymene), 5.42 (d, J = 6.4 Hz, 1 H, Hb

in p-cymene), 5.64 (d, J = 6.4 Hz, 1 H, Hd in p-cymene), 5.69 (d, J =6.4 Hz, 1 H, Hc in p-cymene), 6.83 (d, J = 2.6 Hz, 1 H, H6 in salicylald-imine), 6.92 (d, J = 8.8 Hz, 1 H, H3 in salicylaldimine), 7.25 (d, J =6.6 Hz, 2 H, H3 and H5 in 4-methylpyridine), 7.32 (dd, J = 8.8, 2.6 Hz,1 H, H4 in salicylaldimine), 7.74 (s, 1 H, -N=CH-), 8.52 (d, J = 6.6 Hz,2 H, H2 and H6 in 4-methylpyridine) ppm. MS (ESI): m/z = 561 [M –PF6]+. HRMS (ESI): calcd. for C25H36NO102Ru [M – 4-MePy – PF6]+

468.1840; found 468.1862.

3c (R1 = tBu, R2 = nBu, X = PPh3): Brown solid (99 %), m.p. 102–103 °C. IR (KBr): ν̃ = 3055, 2958, 2870, 1616, 1535, 1479, 1435, 1393,1361, 1315, 1258, 1180, 1093, 1028, 831, 743, 694 cm–1. 1H NMR(CDCl3, 300 MHz): δ = 0.84 (t, J = 7.4 Hz, 3 H, -NCH2CH2CH2CH3),1.02 [d, J = 6.9 Hz, 3 H, -C6H4CH(CH3)CH3], 1.17 [d, J = 6.9 Hz, 3 H,-C6H4CH(CH3)CH3], 1.22 [s, 9 H, -C(CH3)3], 1.23–1.32 (m, 2 H,-NCH2CH2CH2-), 1.33–1.50 (m, 1 H, -NCH2CHH-), 1.67 (s, 3 H,-C6H4CH3), 1.69–1.80 (m, 1 H, -NCH2CHH-), 2.60 [sept, J = 6.9 Hz, 1H, -C6H4CH(CH3)2], 3.38 (ddd, J = 16.1, 10.5, 4.0 Hz, 1 H, -NCHH-),4.07 (ddd, J = 16.1, 10.8, 6.0 Hz, 1 H, -NCHH-), 5.11 (d, J = 6.6 Hz, 1H, Ha in p-cymene), 5.52 (d, J = 6.6 Hz, 1 H, Hb in p-cymene), 5.56(d, J = 6.6 Hz, 1 H, Hc in p-cymene), 6.03 (d, J = 6.6 Hz, 1 H, Hd inp-cymene), 6.64 (d, J = 8.7 Hz, 1 H, H3 in salicylaldimine), 6.72 (d,J = 2.6 Hz, 1 H, H6 in salicylaldimine), 7.17 (dd, J = 8.7, 2.6 Hz, 1 H,H4 in salicylaldimine), 7.28–7.49 (m, 15 H, PPh3), 7.39 (s, 1 H, -N=CH-) ppm. MS (ESI): m/z = 730 [M – PF6]+. HRMS (ESI): calcd. forC25H36NO102Ru [M – PPh3 – PF6]+ 468.1840; found 468.1863.

Single-Crystal XRD Measurements: Crystals suitable for XRD stud-ies were obtained and subsequently analyzed by using a Rigaku R-AXIS RAPID imaging plate diffractometer with graphite-monochro-mated Mo-Kα radiation (λ = 0.71075 Å). The structures of 1a, 2aa


and 2dc were solved by direct methods and refined by full-matrixleast-squares methods. In subsequent refinement, the functionΣw(Fo

2 – Fc2)2 was minimized, Fo and Fc being the observed and

calculated structure factor amplitudes, respectively. The positionsof non-hydrogen atoms were determined from difference Fourierelectron density maps and refined anisotropically. All calculationswere performed by using the Crystal Structure crystallographic soft-ware package, and illustrations were drawn using ORTEP.[20] Detailsof the structural determinations are given in Table 1.

CCDC 1448243 (for 1a), 1448244 (for 2aa), and 1448245 (for 2dc)contain the supplementary crystallographic data for this paper.These data can be obtained free of charge from The CambridgeCrystallographic Data Centre.

AcknowledgmentsThis work was supported by a Grant-in-Aid for Scientific Re-search from the Ministry of Education, Culture, Sports, Scienceand Technology (MEXT), Japan. N. K. also wishes to thank theJikei University Research Fund for financial support.

Keywords: Kinetics · Chirality · Inversion · Ruthenium

[1] a) A. Togni, T. Hayashi (Eds.), Ferrocenes: Homogeneous Catalysis, OrganicSynthesis, Materials Science, Wiley-VCH, Weinheim, Germany, 1995; b) A.Togni, R. L. Halterman (Eds.), Metallocenes: Synthesis - Reactivity - Applica-tions, Wiley-VCH, Weinheim, Germany, 1998, vol. 1–2; c) H. Brunner,Angew. Chem. Int. Ed. 1999, 38, 1194–1208; Angew. Chem. 1999, 111,1248; d) H. Brunner, T. Tsuno, Acc. Chem. Res. 2009, 42, 1501–1510.

[2] a) H. Brunner, M. Langer, J. Organomet. Chem. 1975, 87, 223–240; b) H.Brunner, J. Aclasis, M. Langer, W. Steger, Angew. Chem. Int. Ed. Engl. 1974,13, 810–811; Angew. Chem. 1974, 86, 864.

[3] a) H. Brunner, H. Ike, M. Muschiol, T. Tsuno, N. Umegaki, M. Zabel, Orga-nometallics 2011, 30, 414–421; b) H. Brunner, M. Muschiol, T. Tsuno, H.Ike, T. Kurosawa, K. Koyama, Angew. Chem. Int. Ed. 2012, 51, 1067–1070;Angew. Chem. 2012, 124, 1092; c) H. Brunner, H. Ike, M. Muschiol, T.Tsuno, K. Koyama, T. Kurosawa, M. Zabel, Organometallics 2011, 30,3666–3676; d) H. Brunner, M. Muschiol, T. Tsuno, T. Takahashi, M. Zabel,Organometallics 2010, 29, 428–435; e) H. Brunner, M. Muschiol, T. Tsuno,T. Takahashi, M. Zabel, Organometallics 2008, 27, 3514–3525; f ) V. Alezra,G. Bernardinelli, C. Corminboeuf, U. Frey, E. P. Kündig, A. E. Merbach, C. M.Saudan, F. Viton, J. Weber, J. Am. Chem. Soc. 2004, 126, 4843–4853.

[4] H. Brunner, K. Fisch, P. G. Jones, J. Salbeck, Angew. Chem. Int. Ed. Engl.1989, 28, 1521–1523; Angew. Chem. 1989, 101, 1558.

[5] a) H. Brunner, R. Oeschey, B. Nuber, Angew. Chem. Int. Ed. Engl. 1994, 33,866–868; Angew. Chem. 1994, 106, 941; b) H. Brunner, R. Oeschey, B.Muber, J. Chem. Soc., Dalton Trans. 1996, 1499–1508; c) H. Brunner, R.Oeschey, B. Nuber, Inorg. Chem. 1995, 34, 3349–3351.

[6] H. Brunner, A. Köllnberger, T. Burgemeister, M. Zabel, Polyhedron 2000,19, 1519–1526.

[7] H. Brunner, J. Klankermayer, M. Zabel, Organometallics 2002, 21, 5746–5756.

[8] a) H. Brunner, T. Zwack, Organometallics 2000, 19, 2423–2426; b) V. Rit-leng, P. Bertani, M. Pfeffer, C. Sirlin, J. Hirschinger, Inorg. Chem. 2001, 40,5117–5122.

[9] H. Asano, K. Katayama, H. Kurosawa, Inorg. Chem. 1996, 35, 5760–5761.[10] V. Alezra, G. Bernardinelli, C. Corminboeuf, U. Frey, E. P. Kündig, A. E.

Merbach, C. M. Saudan, F. Viton, J. Weber, J. Am. Chem. Soc. 2004, 126,4843–4853.

[11] For ultrasound-induced aggregation, see: a) T. Naota, H. Koori, J. Am.Chem. Soc. 2005, 127, 9324–9325; b) N. Komiya, T. Muraoka, M. Iida, M.Miyanaga, K. Takahashi, T. Naota, J. Am. Chem. Soc. 2011, 133, 16054–16061; c) M. Naito, R. Inoue, M. Iida, Y. Kuwajima, S. Kawamorita, N. Ko-miya, T. Naota, Chem. Eur. J. 2015, 21, 12927–12939.

[12] For solid-state emission, see: a) N. Komiya, M. Okada, K. Fukumoto, D.Jomori, T. Naota, J. Am. Chem. Soc. 2011, 133, 6493–6496; b) N. Komiya,

https://www.ccdc.cam.ac.uk/services/structures?id=doi:10.1002/ejic.201600221

http://www.ccdc.cam.ac.uk/

http://www.ccdc.cam.ac.uk/

Full Paper

M. Okada, K. Fukumoto, K. Kaneta, A. Yoshida, T. Naota, Chem. Eur. J.2013, 19, 4798–4811; c) N. Komiya, M. Okada, K. Fukumoto, S. Iwata, T.Naota, Dalton Trans. 2014, 43, 10074–10085; d) N. Komiya, M. Okada, M.Hoshino, N. H.-T. Le, T. Naota, Eur. J. Inorg. Chem. 2014, 6085–6096; e) K.Fukumoto, N. H.-T. Le, N. Komiya, T. Naota, Inorg. Chem. Commun. 2014,50, 88–91.

[13] For molecular mobility, see: a) M. Naito, H. Souda, H. Koori, N. Komiya,T. Naota, Chem. Eur. J. 2014, 20, 6991–7000; b) R. Inoue, S. Kawamorita,T. Naota, Chem. Eur. J. 2016, 22, 5712–5726.

[14] A. D. Bain, Prog. Nucl. Magn. Reson. Spectrosc. 2003, 43, 63–103.[15] H. Brunner, T. Neuhierl, B. Nuber, Eur. J. Inorg. Chem. 1998, 1877–1881.


[16] A. J. Davenport, D. L. Davies, J. Fawcett, D. R. Russell, Dalton Trans. 2004,1481–1492.

[17] S. K. Mandal, A. R. Chakravarty, Polyhedron 1992, 11, 823–827.[18] P. M. H. Budzelaar, g NMR, version 4.1.0, Cherwell Scientific Publishing

Ltd., Oxford, Great Britain.[19] M. Rekharsky, Y. Inoue, J. Am. Chem. Soc. 2000, 122, 4418–4435.[20] M. N. Burnett, C. K. Johnson, ORTEP-III: Oak Ridge Thermal Ellipsoid Plot-

Program for Crystal Structure Illustrations, Report ORNL-6895, Oak RidgeNational Laboratory, Oak Ridge, TN, 1996.

Received: March 2, 2016Published Online: May 27, 2016

kinetic studies of the chirality inversion of salicylaldiminato ruthenium using racemic h6-p-cymene...

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