2334

- + (\TI) PII = Ir; L = ilJeCN (VII) M = Rh; L = Ph,P

(VIII) M = Rh; L, = diphos (XI) M = Ir; L = Ph,P

(XII) M = I r ; L = MePh,P

(XIV) M = I r ; L, = diphos

1 p M c : 1 (XIII) M = I r ; L = Ph,POA'le

J. Chem. SOC. (A), 1971

Cationic Taansition-metal Complexes. Part 1. Synthesis and Reactions of Bis(diene)-rhodium and -iridium Tetrafluoroborates

By M. Green," T. A. Kuc, and Susan H. Taylor, Department of Inorganic Chemistry, University of Bristol, Bristol BS8 1TS

Reaction of [M(dien)(acac)] (M = Rh or I r ; diene = 1,5-C8HI, or bicyclo[2,2,l]heptadiene) with Ph,C+BF,- in the presence of an excess of diene affords [M(diene),]+BF,-, from which diene is readily displaced by aceto- nitrile to form [M(diene)(CH,CN),]+BF,-. Reaction of [M (diene)(CH,CN),]+BF,- with phosphines and bi- pyridyl are described; complexes of the type [M(diene)L,]+BF,- and [ML4]+BFa- being formed depending on the nucleophilicity of the ligand L. Reaction of [M(1,5-CaHl,),]+BF4- with sodium iodide in acetone affords [M (1 ,5-C8H12)I],. Methanol reacts with [ lr( l ,5-C8Hl2),]+BF4- in the presence of sodium carbonate to give [Ir( l ,5-C8Hl2)OMeI2; a mixture of syn- and anri-isomers.

IT is well established1 that reaction of the bridged d8 complexes [M(diene)Cl], (M = Rh or Ir, diene = 1 ,5-C8H12 or bicyclo[2,2,l]heptadiene) with group v donors (L) affords the neutral species [M(diene) (L)Cl]. R e ~ e n t l y , ~ , ~ it has been reported that a further reaction occurs with triphenylphosphine in alcohols or nitro- methane to give the cationic complexes [M(diene)- (PP h3) ,] + , isolated as t e t r aphen y lb or at e or perchlor ate salts. The reaction of [Rh(l ,6-C8H12) (acac)] with Ph,C+BF4- in the presence of phosphines (L) has also been shown to give the cations [Rh(l,5-C8H12)L2]fBF,-.

An alternative and potentially more general route to cationic RhI and IrI complexes would involve displace- ment reactions of the complexes [M(1,5-C8H,,),]+~- (M = Rh or I r ; X = BF,-, PF,-, etc.). Such com- plexes have been r e p ~ r t e d , ~ but the synthesis, which involved addition of NaBPh, to [M( 1,5-C8H12)2SnC13] (M = Rh or Ir), did not represent a practical route to the required compounds. Here we report some of the re- actions and a general synthesis of the tetrafluoroborate salts of the cations [M(diene)J+ (M = Rh or Ir; diene = 1,5-C8H12 or C,H8). The new compounds described were characterised by elemental analysis and i.r. and lH n.m.r. spectroscopy.

Treatment of a solution of [M(diene)(acac)] (M = Rh or Ir) in methylene chloride with an equimolar propor- tion of triphenylmethyl tetrafluoroborate, in the presence of an excess of diene (1,5-C,H12 or bicyclo[2,2,l]hepta- diene), led to an instantaneous reaction with colour changes from yellow to deep purple-red or red. The addition of diethyl ether gave good yields of the com- plexes (I), (11), and (111) as reasonably air-stable I- I

crystalline solids, soluble in methylene chloride. The i.r. spectra of (I), (11), and (111) all showed strong

bands between 1090 and 1050 cm-l characteristic of the tetrafluoroborate anion, and the lH n.m.r. spectra showed resonances corresponding to the presence of only co- or dinat ed cyclo-oct a- 1,5-diene or bicyclo [2, 2,1] hept a- diene, suggesting that t he complexes are co-ordinatively unsaturated square-planar d* cations as illustrated.

J. Chatt and L. M. Venanzi, J . Chem. SOL, 1957, 4735; M. A. Bennett and G. Wilkinson, J . Chem. SOC., 1961, 1418; L. Cattalini, R. Ugo, and A. Oris, J . Amer. Chem. SOC., 1968, 90, 4800; K. Vrieze, H. C. Volger, and A. P. Praat, J . Ovganometallac Chenz., 1968, 15, 195.

L. 11. Haines, Inorg. Nuclear Chew. Letters, 1969, 5, 399; Inoyg. Chem., 1970, 9, 1517.

The cations (I), (11), and (111) easily react with both 0-donor and x-acceptor ligands ; the reactions probably

(I) M = Rh (111) hl = I r

(11) 11 = Rh

r 1 r l+

L\,/L

L ' 'L

L L J (V) M = Rh; L = MeCN (XVI) M = I r ; L = MePh,P

(IX) M = R h ; L = Ph,P (XVII) M = I r ; L = Ph,POMe (X) hl = R h ; (XVIII) M = Rh; L = Me2PhP

L = MePh,P

involve five-co-ordinate intermediates. Here, the re- action with acetonitrile, a ligand which normally does not function as a x-acceptor, is described. The corre- sponding reactions with olefins, arenes, and carbon mon- oxide will be discussed in a subsequent paper.

Treatment of a solution of either bis(cyc1o-octa- 1,5-diene)-rhodium or -iridium tetrafluoroborate or bis- (bicyclo[2,2,1] hept adiene) rhodium tetrafluoroborate with acetonitrile resulted in an immediate colour change from deep red to yellow, and the displacement of one molecular equivalent of diene. On addition of diethyl ether the yellow crystalline bis(acetonitri1e) complexes (IV), (V) ,

J. R. Shapley, R. R. Schrock, and J. A. Osborn, J . Amer.

4 B. F. G. Johnson, J. Lewis, and D. A. White, J . Amev.

6 J. F. Young, R. D. Gillard, and G. Wilkinson, J . Amev. Chem.

Chena. SOC., 1969, 91, 2816.

Chem. SOC., 1969, 91, 5187.

SOC., 1969, 91, 5187.

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Inorg. Phys. Theor. 2335

and (VI) were precipitated as stable solids insensitive to air.

The i.r. spectra of the acetonitrile complexes (IV), (V), and (VI) showed, aside from bands due to tetrafluoro- borate, two strong bands in the 2300 and 2320 cm-l region, which are assigned to co-ordinated acetonitrile ; the free nitrile showed corresponding bands at 2254 and 2295 cm-l. This increase in vCN on co-ordination may be ascribed to both a coupling of the C-N and N-metal stretching vibrations and to an increased E N force constant.’ If there was back-bonding from filled rhod- ium or iridium d-orbitals into nitrile 5t* orbitals then a decrease in vm would be expected on co-ordination.8 The implied donation of electron density to the rhodium or iridium atom by the acetonitrile ligands could result in an increase in backbonding into the x* orbitals of the remaining diene molecule.

This effect is possibly reflected in the upfield shift (7 1.0) of the olefinic proton n.m.r. resonances of the re- maining co-ordinated cyclo-octa-1 ,5-diene or bicyclo- [2,2,l]heptadiene relative to the resonance of the corre- sponding [M(diene)J+ protons. However, an alternative explanation for the upfield shift is a cis magnetic aniso- tropic effect by the CZN triple bond.

The lH n.m.r. resonance of the methylene protons of the cyclo-octa-1,5-diene ligand in (IV) and (VI) is split into two multiplets of equal intensity suggesting a different environment for the ‘ inside ’ and ‘ outside ’ protons. The spectra of (IV), (V), and (VI) showed, in addition, a single sharp resonance at 7 7.6-7-7 which is assigned to the CH3CN resonance of co-ordinated aceto- nitrile.

Whereas, reaction of the cations [M(diene)J + with phosphorus ligands was not selective and led to mixtures of products, the extreme lability of the acetonitrile ligands in (IV), (V), and (VI) towards ligand exchange provided a route to the cations [M(diene)L,]+BF,-.

Treatment of a solution of (IV), (V), or (VI) in methyl- ene chloride with triphenylphosphine resulted in an immediate reaction as evidenced by the change in colour from yellow to red; addition of diethyl ether to the reaction mixture afforded (VII), (IX), and (XI) re- spectively in good yield as crystalline complexes. Simi- larly, reaction of (IV) with 1,2-bis(diphenylphosphino)- ethane, (VI) with methyldiphenylphosphine, or (V) with methyldiphenylphosphine, methyl diphenylphosphinite, 1 ,2-bis(diphenylphosphino)ethane, or 2,2’-bipyridyl gave good yields of the crystalline cations (VIII), (X), (XII), (XIII), (XIV), and (XV) respectively.

Predictably, the chelating ligand Ph,PCH,*CH,PPh, reacted further with both (VIII) and (XIV) to give the known cations [M(diphos)J +BF,-; however, treatment of (XV) with more 2,2’-bipyridyl gave no further re- action. A similar displacement of the diene was ob- served on reaction of ( X I ) with more PPh,Me or (XIII)

T. L. Brown and 31. Kubota, J . Anzer. Chew,. Soc., 1961, 83,

7 I<. I?. Purcell and R. S. Drago, J . Amer. Chenz. SOC., 1966, 4175.

88, 919.

with more PPh,OMe to give the tetrakis-substituted cations (XVI) and (XVII). Interestingly, treatment of (IV) with dimethylphenylphosphine led to the suc- cessive replacement of acetonitrile and cyclo-octa-l,5-di- ene and the formation of [Rh(PPhMe,),]+BF,- (XVIII). The cations (XVI), (XVII), and (XVIII) were obtained as air-sensitive crystalline complexes, which undergo a variety of oxidative-addition reactions. Previously, only the four-co-ordinated rhodium(1) cations [RhL,] +

[L = P(OPh), or P(Bun),] with identical monodentate group V ligands have been described.,

All the complexes (1V)-(XVIII) are depicted as square-planar d8 cations and, therefore, it might be ex- pected that the 1H n.m.r. resonances of the methyl protons of the cis-PPh,Me and PPh,OMe ligands in com- plexes like (XII) and (XIII) would appear as apparent doublets: i.e. an [AX,], system (A = 31P, X = lH) where ,JPp < 50 Hz. However, the spectra of (XII) and (XIII) showed for CH3P and CH,OP two sharp ‘ outer ’ lines and a medium-size envelope of ‘ inner ’ lines indicating a value for ,JPp in the region of 200 Hz. This value is unusually high for a system with cis- phosphorus ligands, but is smaller than the values ob- served (greater than 500 Hz) for mutually tvans-phos- phorus ligands .

The reaction of the cationic diene complexes (I) and (111) with nucleophiles was also examined; it being expected that depending on the choice of reagent attack would occur either at the olefinic double bond of the co- ordinated cyclo-octa-1,5-diene or a t the metal atom. The ‘ soft ’ nucleophilic reagent sodium iodide in acetone, reacted with (I) and (111) to give the known compounds [M(1,5-CsHl,)I], (M = Rh or Ir). The cation (111) dis- solved in methanol to give a deep red solution, but on addition of potassium carbonate a hexane-soluble yellow crystalline complex (XIX) was formed; this was charac- terised by elemental analysis (and a molecular-weight

Me

u

measurement in solution) as the dinuclear derivative [Ir(l,5-C,H,,)OMe],. The lH n.m.r. spectrum of (XIX) showed, in addition to resonances due to co-ordinated

8 P. C. Ford and R. E. Clarke, Chem. Comm., 1968, 1109. 9 R. K. Harris, Canad. J . Chem., 1964, 42, 2275. 10 E. 0. Bishop, Ann. Rev. N.M.R. Spectroscopy, 1968, 1, 91.

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2336 J. Chem. SOC. (A), 1971

cyclo-octa-l,5-diene, two sharp singlet resonances of equal intensity at T 6-82 and 8.78. It is suggested that the product obtained is a mixture of the syn- and anti- isomers (XIXa) and (XIXb) ; the reaction involving nucleophilic attack by the ' hard ' methoxide nucleophile at the iridium atom. The complex [Ir(l,5-C8H,)OMe], has been previouslyll obtained by reaction of [Ir(1,5- C8H12)HCIJ2 with methoxide anion, but the possibility of isomers was not considered; moreover, the lH n.m.r. spectrum was not recorded.

EXPERIMENTAL

lH N.m.r. spectra were measured on a Varian Associates HA 100 spectrometer a t 100 MHz; chemical shifts are relative to Me,Si (T 10.00). Infrared spectra were recorded as Nujol mulls on a Perkin-Elmer 257 spectrophotometer. Reactions were, in general, conducted in an atmosphere of dry oxygen-free nitrogen.

Synthesis of Bis(cyclo-octa-l,5-diene)rhodium Tetrafluoro- borate .-Acetylacetonato (cyclo-octa- 1,5-diene)rhodium (2.8 g. , 9-1 mmoles) and cyclo-octa-1,bdiene (5 ml. excess) were dissolved in methylene chloride (20 ml.), and triphenyl- methyl tetrafluoroborate (2.98 g., 9.1 mmoles) in methylene chloride (40 ml.) was added dropwise to the stirred (25") yellow solution. After the addition was complete the deep red solution was stirred for 5 min. and then added to diethyl ether (400 ml.) to give orange-red crystals of (I) bis(cycl0- octa-1,5-diene)rhodium tetrafluoroborate (3.44 g., 94%), m.p. 206-208" (Found: C, 47.4; H, 6-0. C,,H,,BF,Rh requires C, 47.1; H, 5.9%), Y,,, 1060vs (BF,) and 1030vs cm-l (BF,); T (CDCl,) 4.67 (s, 8H, CH=CH) and 7.47br (s, l6H, CH,CH,).

Synthesis of Bis(bicycZo[2,2,l]heptadiene)rhodiunz Tetra- fluoroborate.-Similarly, triphenylmethyl tetrafluoroborate (1.79 g., 5.4 mmoles) in methylene chloride (15 ml.) was added dropwise to a stirred solution of acetylacetonato- (bicyclo[2,2,l]heptadiene)rhodium (1.6 g., 5-4 mmoles) and bicyclo[2,2, llheptadiene (5 ml., excess) in methylene chloride. After 5 min. at room temperature the deep red solution was added to diethyl ether (200 ml.) to give red crystals of (11) bis(bicyclo[2,2,l]heptadiene)rhodium tetrafluoroborate (1.8 g., 89%), m.p. 157-159" (Found: C, 44.8; H, 4.4. Cl,Hl,BF,Rh requires C, 44-8; H, 4-3y0), vmaE 1053 (BF,) and 1038 cm.-l (BF,); T (CDC1,) 4.47 (d, 8H, CH=CH), 5-81 (s, 4H, CH), and 8-43 (s, 4H, CH,).

Synthesis of Bis(cyc1o-octa- 1,5-diene) iridium Tetrafluoro- borate.-In a similar manner to that described in the pre- ceding experiment triphenylmethyl tetrafluoroborate (2- 73 g., 8-27 mmoles) in methylene chloride (40 ml.) was added dropwise to a stirred solution of acetylacetonato (cyclo- octa-1,5-diene)iridium (3-32 g., 8-27 mmoles) and cyclo- octa-1,5-diene (5 ml. excess) in methylene chloride (60 ml.). After 5 min. the deep purple-red solution was added to di- ethyl ether (400 ml.) to give deep purple-brown crystals of (111) bis(cyclo-octa-l,5-diene)iridiuin tetrafluoroborate (3.05 g., 73%), m.p. 140-145" (Found: C, 38.8; H, 4.8; Ir, 38.2. C,,H,,BF,Ir requires C, 38-8; €3, 4-9; Ir, 38-80,;), v,,,. 1089vs (BF,) and 1051vs cm-l (BF,); z (CDCI,) 4-88 (s, 8H, CH=CH) and 7-60br (s, 16H, CH,CH,).

Reactions of Bis(cyclo-octa-l,5-diene)rhodium Tetrafluoro- borate with A cetonitrile.-Bis(cyclo-octa-l,5-diene)rhodium tetrafluoroborate (1-4 g., 3.45 mmoles) was dissolved in methylene chloride (20 ml.) and acetonitrile (5 ml.) was

added dropwise to the stirred solution. The resultant yellow solution was added to diethyl ether (100 ml.) to give bright yellow crystals of (IV) bis(acet0nitriZe) (cycZo-octa- 1,5-diene) - rhodium tetrafluoroborate (1.15 g., 88%), m.p. 188-190' (Found: C, 37.6; H, 4-8; N, 7-0. C12H18BF,N,Rh re- quires C, 37.9; H, 4.7; N, 7.4y0), vmx 2320s (CN), 2290s (CN), 1060vs (BF,), and 1030vs cm.-l (BF,); T (CDC1,) 5.62 (s, 4H, CH=CH), 7.65 (s, 6H, CH,CN), and 8.1-8-2 (m, 8H, CH,CH,).

Reaction of Bis(bicycZo[2, 2,1]heptudiene)rhodium Tetra- fluoroborute with A cetonitrik-In a similar manner to that described in the preceding experiment reaction of bis- (bicyclo[2,2,l]heptadiene)rhodium tetrafluoroborate (1.2 g., 3.20 mmole) in methylene chloride (20 ml.) with acetonitrile (5 ml.) gave yellow crystals of (V) bis(ucetonitriZe) (bicyclo- [2,2,1]heptadiene)rhodium tetrafluoroborate (1.05 g., goyo), m.p. 111' (Found: C, 36.7; H, 3.9; N, 7.3; Rh, 28.3. Cl,H8BF,N,Rh requires C, 36.3; H, 3.9; N, 7.7; Rh, 28.3%), vmSX 2318s (CN), 2293s (CN), 1065vs (BF,), and 1043 cm-1 (BF,) ; -T (CDCl,) 5-80 (4, 4H, CH=CH, J 2.2Hz), 6-16 (m, 2H, CH), 7.72 (s, 6H, CH,CN), and 8.76 (apparent t , 2H, 3H2, J 3.2 Hz).

Reaction of Bis(cyc1o-octa- 1,Ei-diene)iridiwn Tetrafluoro- borate with Acetonitrile.-In a similar manner to that de- scribed above reaction of bis(cyc10-octa- 1,5-diene)iridium tetrafluoroborate (0-30 g., 0.66 mmole) in methylene chloride (10 nil.) with acetonitrile (2 ml.) gave, after precipitation with diethyl ether (60 ml,), bright yellow crystals of (VI) bis(acetonitde) (cyclo-octa-l,5-diene)iridium tetrafluoroborate (0.20 g., 65%), m.p. 107-108" (Found: C, 30.8; H, 4-0; Ir, 40-2. Cl,Hl,BF,N21r requires C, 30.7; H, 3.8; Ir, 40.9%), v,,,. 2317s (CN), 2292s (CN), 1064vs (BF,), and 1032vs cm.-l (BF,); T (CDCl,) 5-83 (s, 4H, CH=CH), 7.61 (s, 6H, CH,CN), 7.80, and 8.26-8-35 (m, 8H, CH,CH,).

Reactions of Bis(acetonitri1e) (cyclo-octa- 1,5-diene)rhodiuigz Tetrafluoroborate.-(a) With triphenylphosphine. Addition of a solution of triphenylphosphine (0.083 g., 0.315 mmole) in methylene chloride (5 ml.) to a stirred (25") solution of (IV) (0.06 g . , 0.158 mmole) in methylene chloride (10 ml.) resulted in an immediate colour change from yellow to orange-red. The solution was added to diethyl ether (80 ml.) and the precipitate was recrystallised from methylene chloride-hexane to give yellow-orange crystals of bis (tri- phenylphosphine) (cyclo-octa- 1,5-diene)rhodium tetrafluorobor- ate (VII) (0.095 g., 73%), m.p. 192-194" (Found: C, 64.3; H, 5.3. C,,H,,BF,P,Rh requires C, 64-3; H, 5.1%); 7

(CDCl,) 2.72 (m, 30H, C,H,P), 5-40 (S, 4H, CH=CH), and 7-64 (m, 8H, CH,CH,).

(b) With 1,2-bis(diphenylphos~hinoethane). In a similar manner to that described in (a), reaction of (IV) (0-06 g . , 0- 158 mmole) and 1,2-bis(diphenylphosphinoethane) (0,064 g., 0.16 mmole) in methylene chloride (20 ml.) gave, on addition of diethyl ether, orange-yellow crystals of (VIII) 1,2-bis(di~henylPhosphinoethane) cyclo-octa- 1,5-diene rhodium tetrafluoroborate (0.07 g., say0), m.p. 24" (Found: C, 58-5; H, 5.6. C,,H,,BF,P,Rh requires C, 58.7; H, 5.2%) ; T (CDCl,) 2.50 (m, 20H, C,H,P), 5-12 (s, 4H, CH=CH), and 7.64br (s, 12H, CH,CH,).

Reactions of Bis(acetonitr&?e) (bi~y~l0[2,2,1] J8eptadiene)rhod- ium TetrafEuoroborate.-(a) With triphenylphosphine. Addi- tion of a solution of triphenylphosphine (0-072 g., 0-274 mmole) in methylene chloride ( 5 ml.) to a stirred (25") solution of (V) (0.05 g., 0.137 mmole) in methylene chloride

l1 S. D. Robinson and B. L. Shaw, J. Chewz. Soc., 1965, 4997.

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(10 ml.) led to an immediate colour change from yellow to orange. Addition of diethyl ether (60 ml.) gave yellow- orange crystals of (IX) bis(triphenylphosphine) (bicyclo- [2,2,1 ]heptadiene)rhodium tetrafluoroborate (0.055 g., 5oy0), n1.p. 12A126" (Found: C, 63.9; H, 4-6. C,,H,,BF,P,Rh requires C, 64-1; H, 4-7y0), v,, 1058 cm.-l (BF,); T (CD,- COCD,) 2-55 (in, 30H, C,H,P), 5.43 (apparent q, 4H, CH=CH), 5-99 (m, 2H, CH), and 8.51br (s, 2H, CH,).

In a similar manner to that described in (a) reaction of (V) (0.07 g., 0.192 mmole) with methyldiphenylphosphine (0.076 g., 0-38 mmole) gave yellow-orange crystals of (X) bis(methyldiphenylphos- phine) (bicyclo[2,2,1] heptadiene)rhodium tetrafluoroborate (0.068 g., 52y0), m.p. 95" (Found: C, 56.8; H, 4.8; P, 7-8; Rh, 16-5. C,,H,,BF,P,Rh requires C, 57.1; H, 5.0; P, 8.1; Rh, 16.1%); T (CDCl,) 2-61 (m, 20H, C,,H,P), 5.38 (apparent q, 4H, CH=CH), 5.98 (m, 2H, CH), 8-44 (m, 6H, CH,P), and 8.51br (s, 2H, CH,).

Reactions of Bis (acetonitrile) (cyclo-octa- 1,5-diene)iridium Tetra$uoroborate.-( a) With triphenylphosphine. Addition of a solution of triphenylphosphine (0.11 g . , 0.43 mmole) in methylene chloride (2 ml.) to a stirred (25") solution of (VI) (0.10 g., 0-21 mmole) in methylene chloride (5 ml.) resulted in an immediate colour change to bright red. Addition of diethyl ether followed by recrystallisation from methylene chloride-hexane gave red crystals of (XI) bis(triphenylph0s- phine) (cyclo-octa-l,5-diene)iridium tetrafluoroborate (0.16 g., 82%), m.p. 199-200" (Found: C, 57.6; H, 4.8; Ir, 21.4; P, 6.9. C,,H,,BF,IrP, requires C, 57.9; H,4-6; Ir, 21.0; p, 6.8%); vm, 1092s (BF,), 1054s (BF,), and lOOOm cm.-1 (BF,) ; z (CDC1,) 2-75 (m, 30H, C,H,P), 5-86 (s, 4H, CH=CH), and 7-7-8-15 (m, 8H, CH,CH,).

In a similar manner to that described in (a) reaction of (VI) (0.10 g., 0.21 mmole) with methyldiphenylphosphine (0-085 g., 0.43 mmole) in methylene chloride (75 ml.) gave, on immediate precipita- tion with diethyl ether, deep pink crystals of (XII) bis- (methyldipheny Zphosphine) (cyclo-octa- 1,5-diene) iridium tetra- jluoroborate (0.15 g., 89%), m.p. 206-208" (Found: C, 52.1; H, 5.0; Ir, 24.3; P, 8.0. C,,H,,BF,IrP, requires C, 51.9; H, 4.8; Ir, 24-4, P, 7-9%), v,, 1094s (BF,) 1050s (BF,), and 997m cm-l (BF,), z (CDCl,) 2-58 (m, 20H, C,H,P), 5-30 (s , 4H, CH=CH), 7.86 (m, 8H, CH,CH,), and 8.29 (apparent d, GH, CH,P, IJlpc~ 7.5 Hz).

(c) With methyl diphenylphosphinite. Addition of methyl diphenylphosphinite (0.065 g, 0.3 mmole) to a solution of (VI) (0.07 g., 0-15 mmole) in methylene chloride (10 ml.) gave, on addition of diethyl ether, red crystals of (XIII) bis (methyl diphenylp hosphinite) (cyclo-octa- 1,5-diene)iridium tetrafluoroborate (0.065 g., 53%), m.p. 156-158" (Found: C, 49.6; H, 4.7. C,,H,,BF,IrO,P requires C, 49.8; H, 4.6%; 7 (CDCl,) 2.58 (m, 20H, C,H,P), 5.33br (s , 4H, CH=CH), 6.91 (apparent d, 6H, CH,OP, lJlpoC~ 13-2 Hz), and 7.8-8-2 (m, 8H, C.H,CH,).

(d) With 1,2-bis(diphenylplzosphino)ethane. In a similar manner to that described above. Addition of 1,2-bis(di- pheny1phosphino)ethane (0.085 g., 0-21 mmole) to a solution of (VI) (0.10 g., 0.21 mmole) gave red-violet crystals of (XIV) 1,2-bis (diphenyZphosphino)ethane (cyclo-octa- 1,5-diene) ividium tetrafluoroborate (0.12 g., 72y0), m.p. 184-186" (Found: C, 50.5; H, 4.5; Ir, 24.5; P, 7.8. C,,H,,BF,IrP, requires C, 52-1; H, 4.6; Ir, 24.5; P, 7.9y0), vmx. 1094s

(b) Methyldiphenylphosphine.

(b) With wzethyldiphenylphosphine.

(BF,), 1051s (BF,), and 995m cm-l (BF,); T (CDCl,) 2-48 (m, 20H, C,H,P), 5.47 (s, 4H, CH=CH), and 7.8 (m, 12H, CH,CH,).

Addition of 2,2'-bipyridyl (0-033 g., 0.21 mmole) to a solution of (VI) (0.10 g., 0.21 mmole) resulted in an immediate colour change to dark green. Addition of diethyl ether gave dark green crystals of (XV) 2,2'-bipyridyl(cyclo-octa-l, 5-diene)iridium tetrafluoroborate (0.10 g., 81y0), m.p. 260' (Found: C, 39.1; H, 3-7; Ir, 33.9; N, 4.8. C,,H,,BF,IrN requires C, 39.8; H, 3.7; Ir, 35.4; N, 5-1%), vm, 1064s (BF,), 1031s (BF,), and 1004m cm-l (BF,) ; T (CD,COCD,) 1.27-2-17 (m, 8H, Ar), 5.52 (m, 4H, CHZH) , and 8.14 (m, 8H, CH,CH,).

Reaction of (XII) with Methyldiphenylphosphine.-A solution of (XII) (0.04 g . , 0.085 mmole) and methyldiphenyl- phosphine (0.5 g., 2-5 mmole) in acetone was stirred a t room temperature for 10 min. Addition of diethyl ether gave salmon pink crystals of (XVI) tetrakis(methyldiphenylphos- 9hine)iridium tetrafluoroborate (0.03 g., %)yo), m.p. 125- 128" (Found: C, 57.5; H, 5-2. C,,H,,BF,IrP requires C, C, 57.8; H, 4*8%), v,= 1095s (BF,), 1056s (BF,), 998m cm-l (BF,) ; z (CD,COCD,) 2-43-2.79 (m, 40H, C,H,P) and 8-17-8.29 (m, 12H, CH,P).

Reaction of Compound (XIII) with Methyl Diphenylphos- phinite.-A solution of (XIII) (0.06 g., 0.074 mmole) and methyl diphenylphosphinite (0.065 g., 0.3 mmole) in methyl- ene chloride (15 ml.) was stirred at room temperature for 1 hr. Addition of diethyl ether to the mixture gave white crystals of (XVII) tetrakis(methyl diphenylphosphinite) - iridium tetrafluoroborate (0-055 g., 65%), m.p. 156-158" (Found: C, 54.3; H, 4.9. C,,H,,BF,IrOP, requires C, 54.5; H, 4.5%) ; 7 (CDCl,) 2-58-2.80 (m, 40H, C,H,P) and 7.45 (apparent t , 12H, CH,OP, l J lpoa~ 11-4 Hz).

Reaction of Compound (IV) with Dimethylphenylphosphine. -Addition of dimethylphenylphosphine (0.20 g., 1.4 mmoles) to a stirred (25") solution of compound (IV) (0.1 g., 0-26 mmole) in methylene chloride (15 ml.) gave, after 30 min., an orange-red solution. Addition of diethyl ether to the mixture gave orange crystals of tetrakis(dimethyZ- phenyZphosphine)rhodium tetrafluoroborate (XVIII) (0.12 g., 72y0), m.p. 96-98" (Found: C, 51.5; H, 5.7. C32H44- BF,P,Rh requires C, 51.7; H, 5.9y0), v,, 1092s (BF,) and 1053s cm.-l (BF,); T (CD,COCD,) 2-28-2.80 (m, 20H, C,H,P) and 7.6 (apparent t , 24H, CH,P, I J I P c H , 8-0 Hz.

Reaction of Bis(cycEo-octa-l,5-diene)iridiurn Tetrafluoro- borate with Methanol.-Potassium carbonate (0.10 g.) was added to a stirred (25") solution of bis(cyclo-octa-1,5-diene)- iridium tetrafluoroborate (0-15 g., 0-3 mmole) in anhydrous methanol (1 0 ml.) . The colour of the solution changed from deep red to yellow. After 10 min. the solvent was removed in vacuo and the residue was extracted with n-hexane. Reduction of the volume of the solvent in vacuo and cooling of the mixture (0") gave yellow crystals of (XIX) (0-02 g., 15y0), m.p. 180" [Found: C, 32.5; H, 4.4%; M (in benz- ene), 660. C18H301r202 requires C, 32.6; H, 4.5%; M , 6631; z (CDCI,) 6.52 (m, CH=CH), 6-82 (s, OMe), 7.81- 8-63 (m, CH,CH,), and 8.78 (s, OMe).

(e) With 2,2'-bipyridyl.

One of us (T. A. K.) acknowledges support from a B.P. research studentship.

r1/054 Received, January 151k, 19711

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