Indian Journal of ChemistryVol. 25A, February 1986, pp. 155-157

Organosilicon(IV) & Organogermanium(IV) Salicylhydroxamates

P R SHANDILYA, G SRIVASTAVA & R C MEHROTRA*

Department of Chemistry, University of Rajasthan, Jaipur 302004

Received 6 June 1985; revised and accepted 28 August 1985

A number of organosilicontl V) and organogermanium(IV) derivatives ofsalicylhydroxamic acid have been prepared by theinteraction of the corresponding organometal chloride with sodium salt of salicylhydroxamic acid in benzene. Thesederivatives have been characterized on the basis of analytical and spectroscopic (IR and PM R) data. On the basis of these data,tetrahedral structures have been proposed for these derivatives tentatively.

The chemistry of metal hydroxamates is well-established1-s. However, the corresponding de-rivatives of salicylhydroxamic acid of transitionmetals" as well as main group elements have been givenless attention. Salicylhydroxamic acid is an interestingmultidentate ligand, which can form different types ofmetal chelates. The derivatives of this ligand with mainGroup (IV) elements are not known. In this paper wereport the synthesis of salicylhydroxamic acidderivatives of organosilicon(IV) and organo-germanium(IV), and their characterisation byanalytical and spectral (IR, PMR) data.

Materials and MethodsSalicylhydroxamic acid was prepared by reported

method 7,8. Organosilicon(IV) and organo-germanium(IV) chlorides were purified by distillation.Silicon and germanium were estimated as oxides. TheIR spectra were recorded as nujol mulls and PMRspectra in COCl3 or acetone-a, using TMS as aninternal reference. Molecular weights were determinedebullioscopically in benzene.

Reactions of organometal(I V) chloride with sodium saltof salicylhydroxamic acid (salicylhydroxamate) indifferent stoichiometric ratios: General procedure

To a suspension of sodium salt of salicylhydroxamicacid, prepared in situ, in benzene-methanol (~5: I), asolution of the required amount of organometal(IV)chloride in benzene was added. The reaction mixturewas relluxed slowly and the precipitated sodiumchloride filtered off. The filtrate was concentratedunder reduced pressure and the solid product obtainedrecrystallized from benzene-pet ether (~I :2) (40-60").Pertinent data regarding the individual experimentsare given in Table l.

Results and DiscussionIn the formation of mono- and bis-triorgano-

silicon(IV) and triorganogermanium(IV) derivatives of

salicylhydroxamic acid, the reactions involved can berepresented by Eqs (1-5).R3MC1 + NaOC6H4CONHOH--+

R3MOC6H4CONHOH + NaCI(I) ... (1)

M = Si; R = CH3, C6HsM=Ge; R=C4H9, C6HS2 R3MCI + NaOC6H4CONHONa--+

R3MOC6H4CONHOMRj + 2 NaCI(II) ... (2)

M=Si; R=CH3, C6HSM = Ge; R = C4H9, C6H. S

R2MCI2 + NaOC6H4CONHONa--+R2M[ -OC6H4CONHO- ]+2NaCH

(III) ... (3)

M=Si; R=CH3, C6HsM=Ge; R=C4H9, C6HSR2MCl2 + 2 NaOC6H4CONHOH--+

R2M[ -O-C6H4CONHOH]2+2NaCIt(IV) ... (4)

M=Si; R=CH3, C6HSM=Ge; R=C4H9, C6HsR2MCI2 + NaOC6H4CONHOH--+

R2M[OC6H4CONHOH]CI + NaCI ~(V) ... (5)

M=Si; R=CH3, C6HsM=Ge; R=C4H9, C6HS

These reactions are quite facile and can be completedwithin 5-6 hr. The products (1-V), which are moisture-sensitive, are either volatile liquids or solids which canbe crystallized from benzene-pet ether (40-60').

The structures of the various products have beenestablished on the basis of their IR and PMR data. Inthe IR spectrum of the free ligand, the bands appearingin the region 3300-3100 cm - I have been assigned toVNOH and vOH. These bands disappear in the spectra

155

INDIAN J. CHEM., VOL. 25A, FEBRUARY 1986

Table I-Synthesis of Organosilicon(IV) and Organogermanium(IV) Salicylhydroxamates

SI R4-.MCl. Methods of Product Yield Found (Calc.), '10No. synthesis ( 'I~)

(equation Si NNo.)

Reaction with organosilicon(/ V) chlorides

(CH3)2Si( - OC6H4CONHO -)White solid (b.p. 188 /4mm)(CH3)(C6H,)Si( - OC6H4CONHO -)Light pink solid (m.p. 164)(C6H,hSi( - 0 - C6H4CONHO -)White solid (m.p. 162)(CH3)(C6HshSi( -0- C6H4CONHOH)Creamish solid(C6HshSi( -OC6H4CONHOH)C1Creamish solid (dec. 185 C)(CH3hSi( -OC6H4CONHOH)C1Pink solid (m.p. 158)(CH3)(C6Hs)Si( - OC6H4CONHOH)C1Light pink solid (m.p. 158)(CH,bSi( -OC6H4CONHOH)Colourless liquid (b.p. 91-93 /

1.6-1.7 mm)(CH,),Si( - OCbH4CONHOSi)(CH3hWhite solid(CH3hSi( -OCbH4CONHOHhWhite solid (m.p. 173°)

Reaction with orgl1llOgermanium(1 V) chlorides

(I)

2 (3)

3 (3)

4 (I)

5 (5)

6 (5)

7 (5)

8 (I)

9 (2)

10 (4)

(3) (C4H9)2Ge( - OC6H4CONHO -)Brown viscous liquid(C6Hs)2Ge( - OC6H4CONHO -)White solid (m.p. 220 )(CbHshGe( -OC6H4CONHOH)White solid (rn.p. 134-135 )(C4H9hGe( -OC6H4CONHOH)Pinkish white solid (m.p. 151°)(C6Hs)6Ge2( -OC6H4CONHO-)White solid (m.p. 179 )(C6HshGe( -OC6H4CONHOH)C1Creamish white solid (rn.p. 138 )(C6HshGe( -OC6H4CONHOHhWhite solid (dec. 280-285 )(C4H9hGe( - OC6H4CONHOH)C1Pinkish solid (rn.p. dec. 159 )(C4H9hGe( -OC6H4CONHOHhWhite solid (rn.p. dec. 240 )(C4H9)6Ge2( -OC6H4CONHO)White solid (rn.p. 164 )

2 (3)

3 (I)

4 (I)

5 (C6HshGeCI (2)

6 (5)

7 (4)

8 (5)

9 (4)

10 (2)

96 13.00(13.39)10.01

(10.33)8.12

(8.38)7.80

(8.02)7.39

(7.57)11.25

(11.45)8.82

(9.13)12.35

(12.52)

6.48(6.49)5.03

(5.16)3.85

(4.19)4.10

(4.01)3.55

(3.78)5.57

(5.72)4.33

(4.56)5.89

(6.27)

4.62(4.71)7.45

(7.73)

4.03(4.14)3.48

(3.48)2.83

(3.07)3.06

(3.54)1.70

( 1.84)3.01

(3.38)2.18

(2.68)13.25

(13.74)2.31

(2.85)2.11

(2.19)

of the complexes indicating the formation of productsvia deprotonation of NHOH and OH (phenolic)groups. In the complex of type (I), the phenolic protonis replaced by metal moiety, similar to that in somemetal salicyladoximes'i'!", oximesll,12, etc. The V(N-0) modes" in the complexes appear in the region840-910 em - I. The v(C = 0) modes in the complexesappear at 1615-1630 em -I, while in the free ligand lC= 0 appears at 1620 em -I. This almost negligible shiftindicates that the carbonyl oxygen of the ligand is notinvolved in the coordination and suggests that these

complexes of Si(IV) and Ge(IV) should containtetracoordinated silicon and germanium.

The bands appearing in the regions 740-760 ern - 1

(in the case of organosilicon(IV) derivatives) and 460-530 cm - 1 (in the case of organogermanium(IV)derivatives) have been assigned to v(Si - 0) and v(Ge-0), respectively 13. The v(Si -CH3)13 vibrationsappear in the range 1240-1270 cm - 1 in the presentcomplexes, while the (Si - 0 - N)14 modes appear inthe range 1030-1100 em -I.

The signals in the PMR spectrum of the ligand at

156

96

93

97

93

94

94

94

92 19.24(19.52)

7.50(7.75)

96

90 21.13(21.44)19.00

(19.18)15.81

(15.93)18m

(18.35)18.97

(19.15)17.04

(17.53)13.13

(13.68)19.06

(19.40)14.12

(14.78)22.53

(22.67)

77

98

94

90

92

92

85

91

98

SHANDILYA et al.: ORGANOSILICON(IV) & ORGANOGERMANIUM(IV) SALICYLHYDROXAMATES

Table 2-PMR Spectral Data of Organosiliconll V) and Organogermanium(IV) Salicylhydroxamates

SI No. Complex Chemical shift (b, pprn)I (CH3hSi( -OC6H4CONHOH) 0.35 (s, 9H, 3 x Si-CH3), 10.75 (s, IH, -OH), 6.5-7.8 (m. 4H, aromatic).2 (C6HshSi( -OC6H4CONHOH)(CHJ) 0.9 (s, 3H, SiCH3), 6.8-7.8 (m, 14H, aromatic), 3.0-5.2 (b. IH, NH), 11.3(s, IH,

-OH alcohol).3 (C6HshSi( - OC6H4CONHOH)C1 3.2-5.0 (b, IH, N - H), 6.5-7.8 (m, 14H, aromatic), 11.2 (s, IH, N - OH).4 (CH3hSi( -OC.H4CONHO -) 0.25 (s, 6H, 2 x Si - CHJ), 6.1-7.8 (m, 4H, aromatic).5 (C6HshSi( -OC.H4CONHO -) 2.8-3.6 (b, IH, NH), 6.8-7.8 (m, 14H, aromatic).6 (C6Hs)(CH3)Si( - OC6H4CONHO -) 0.5 (s, 3H, Si -CH3)' 3.4 (s, tH, NH), 7.0-7.8 (m, 9H, aromatic).7 (C4H9hGe(-OC.H4CONHO-) 5.7 (s, IH, N-H), 0.6-1.8 (m, 19H, Ge-C4H9), 6.7-8.0 (m, 10H, aromatic).8 (C6HshGe( -OC6H4CONHO -) 6.4-8.0 (m, 14H, aromatic), 3.2-4.0 (b, IH, N - H).9 (C6HshGe( -OC6H4CONHOH)C1 11.1 (s, IH, N -OH), 6.8-8.2 (m, 4H, aromatic).

10 (C4H9hGe( - OC6H4CONHOH)C1 10.9 (s, IH, N -OH), 6.8-8.2 (m, 4H, aromatic).II (C6HshGe( -OC6HsCONHOH) 11.1 (s, IH, N -OH), 6.8-8.2 (m, 19H, aromatic).12 (C4H9)6Ge2(-OC6H4CONHO) 5.7 (s, IH, N - H), 0.6-1.8 (m, 18H, 2 x Ge-C4H9) 6.4-8.0 (m, 4H, aromatic).13 (C.HS)6Ge2( - OC6H4CON HO) 7.0-8.0 (m, 34H, aromatic).

{)11.4 and 12.5 due to -OH and -NOH protonsrespectively, disappear in the spectra of the complexes.The protons of the butyl, ethyl and phenyl groupsattached to silicon or germanium appear as multipletswhile methyl protons appear as sharp singlets(Table 2).

On the basis of above IR and PMR data thefollowing structures (I-V) can be suggested for thecompounds.

~OMR3

&CNHOHIIo

~O-MR3

&C-N-OMRII I 3

(!I) 0 HR R\ I

rQY0-M:>~C-N

II I

(

r(3YO~OMR2 H

~\i-~-O~o H

IIV)

(I)

rQY0MR2Cl

~CNHOHII

(V) 0

AcknowledgementOne of the authors (P R S) is thankful to the UGc,

New Delhi for financial assistance.

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