also observed in both the complexes in the region900-725. Similar behaviour of the other metalcomplexes with o-phenanthroline was observed bySchilt and Taylor22•

References1. FRERE, F., ]. Am. chem, Soc., 55 (1933), 4362.2. WENDLANDT, W. W., Analyt . Chem., 28 (1956), 499.3. GANS, P. & SMITH, B. C.,]. chem, Soc., (1964),4172.4. BAGNALL, K. W., DEANE, A. M., MARKIN, T., ROBINSON,

P. S. & STEWART, A. M.,]. chem, Soc ., (1961), 1611.5. BAGNALL, K. W., BROWN, D., JONES, P. J. & ROBINSON,

P. S., ]. chem, Soc ., (1964), 2531.6. GANS, P., Ph.D. Thesis, London University, 1964.7. GANS, P. & SMITH B. C.,]. chem, Soc., (1964),4177.8. BAGNALL, K. W., BROWN, D. & JONES, P. J., ]. chem .

Soc., (1966), 741.9. WEISSBERGER, A. W. & PROSKAUER, E. S., Organic

solvents: Physical properties and methods of purification(Interscience, New York), 1965.

10. CORPEL J. & REGNAUD, F., Anal. chim, Acta, 27 (1962),36.

11. ABRAHAMS, S. C., Acta Cryst., 10 (1957), 417.12. ADDISON, C. C. & SHELDON, J. C., ]. chem . Soc., (1956),

2705.13. BEYNON, J. H., Dictionary of organic compounds, Vol. 3,

1943, 887.14. HAYTON, B. Ph.D. thesis, London University, 1967.15. WASSEF, MARGUERITE A. Ph.D. thesis, London Univer-

sity, 1967.16. NAKAMOTO, K., Infrared spectra of inroganic and coordi-

nation compounds (John Wiley, London), 1963, 77.17. BELLAMY, L. J., The infrared spectra of complex mole-

cules (Methuen, London), 1960.18. LAPPERT, M. F., ]. chem, Soc., (1962), 542.19. BELLAMY, L. J., The infrared spectra of complex mole-

cules (Methuen, London), 1960.20. GUNDUZ, N., SMITH, B. C. & \VASSEF, MARGUERITE A.,

Communications de la [aculte des sciences de l'unioersit«d'Ankara, 16B (1969), 31.

21. SMITH, B. C. & WASSEF, MARGUERITE A., ]. chem . Soc.,(1968), 1817.

22. SCHILT, A. A. & TAYLOR, R. C.,]. inorg . nucl, Chem., 9(1959), 211.

Tris(trimethyl-stannyl,- germy], -siJyl)borates

S. K. MEHROTRA, G. SRIVASTAVA & R. C. MEHROTRA*

Department of Chemistry, University of RajasthanJaipur 302004

Received 12 June 1975; accepted 18 July 1975

Tris(trimethylstannyl)borate has been synthesizedby the reaction of bis(trimethyltin)oxide with boricacid. Tris(trimethyl-silyl and -gerrnyljborates havebeen prepared by the reactions of tris(tributylstannyl)-borate with trimethylchloro-silane and -germane,The compounds have been characterized on the basisof IR and PMR spectra.

THE reactions of B-O-C linkage, e.g. In alkylborates, have been extensively studied", In

recent years, attention has been directed to deriva-tives having B-O-M linkage2,3. Only a few suchderivatives having B-0-Sil,4 linkage have previouslybeen known. The present paper deals with thesynthesis as well as spectral studies of tris(tri-rnethyl-silyl, -germyl and -stannyl)borates.

The preparation of tris(trimethylsilyl)borate bythe reaction of boric acid with trimethylchlorosilane

*Present address: Delhi University, Delhi 110007.

NOTES

was reported by Abel and Singh-. The correspond-ing germanium and till derivatives, B(0~fMes)3'(M= Ge and Sn) could not be obtained by the aboveroutes. Recently, we synthesized trisrtrimethyl-stannyl)borate by an alternative routes involvingthe reaction

C6HS

2B(OHla +3(MesC;nhO-~2B(OSnMesla+3H20 ... (1).Tris(tributyl-germyl)borate could also be syn-

thesized easily by the above method. The corre-spo.iding reaction between bisjtrimethyl-germanium)oxide and boric acid appears to be quite slow.However, trisjtrirnethyl-g errnyl) borate, B (OGeM esla,could be easily obtained by the interaction between(MeSGe)20 and boric oxide. This reaction did notappear to proceed at all in case of silicon even after24 hr of refluxing.

Thus, the reactivity of bis[trimethyl-metaljoxidewith boric acid (or oxide) decreases in the followingorder: Sn>Ge>Si.

B-O-Sn linkage is readily cleaved by chloro-silanesand chloro-gerrnanes and, therefore, the reactionoffers a convenient route for synthesis of tris(tri-methyl-silyl and -germyl)borates (Eq. 2). Thereactions of tris(tributyl-stannyl)borate with tri-methylchloro-silane or -germane are exothermic andthe products are obtained in quantitative yields.Fractional distillation gave pure products (PMR)as tris(trimethyl-silyl or -germyl)borate distils at alower temperature than tributyl-tin chloride:B(OSnBU3)S +3Me3MCl~B(OMMe3)3 +3BusSnCl

... (2)(M = Si and Ge)

IR spectral absorptions of trisjtrimethyl-silvl,-gerrnyl and -stannyl)borates in the range 3600-400crrr" with tentative assignments have been tabulatedin Table 1.

The Vas (B-O-M) frequencies showed a gradualdecrease in going from silicon (1325 cm-I) viagermanium (1315 em-I) to tin (1300-1285 crrr-). Thetentative assignment of Vas (B-O-M) in the range1305 ± 20 finds support from the following two ob-servations:

(i) During the preparation of tris(trimethylstannyl)borate from bis(trimethyltin)oxide, the strong ab-sorption at 740 em? due to Vas (Sn-0-5n) disappearscompletely and a strong peak appears at 1300-]285

TABLE 1 - INFRARED DATA OF TRIS(TRIMETHYL-SILYL,-GERMYL, -STANNYL)BORATES

Tentativeassign men ts

2970 s2900 w1410 s1370 vs1325 vs1257 vs883 vs842 vs755 vs677 w618 W

2975 m2920 m1400 m1345 vs1315 vs1240 vs

2975 m2920 m1400 wish)1345 vs(sh)1300-1285 vs{br)1188 s

775-65 vs(br)685 s532 vs507 w

vasCH3VSCH38asCH3vas(B03)

vas(B-O-M)8s(CH3)

vas(Si-O)Pas(CH3laMPs(CH3)3MvasC3MvsC3M

821 vs, 725 s755,685 w609 vs568 w

137

INDIAN ]. (HEM., VOL. 14A, FEBRUARY 1976

crrr+. In other respects, the spectra of trisjtrimethvl-tinjoxide are quite similar. (ii) puring the cleava~eor insertion reaction of B-O-Sn linkage, the peak mthe region 1300-1285 crrr- disappears complete~y.

The trirnethyl-metal peak positions in bisttrime-thyl-rnetal] oxide and tris(trimethy~metal)borates(where metal = Si, Ge and Sn) are given below:

Compound 8M(Hz)* Compound 8M(Hz)

(Me3Si).O -3,5 B(OSiMe3la -4-8(Me3Ge).O -18·5 B(OGeMe3). -19,2(l'vle3Sn)20 -14'2 B(OSnMe3la -12'2

*Values taken from literature Angeiu, Glum. (intemat. edn},4 (1965), 201.

The PMR spectra of these derivatives show o~lya singlet for methyl protons thus indicating the purityof the products. The chemical shifts of these peaksappear to be in the same r~nge as for the correspond-ing bisjtrimethyl-metaljoxides. ..

Trb(tributyl-stannyl)borate and trisltrimethyl-stannyl) borate were synth.esized by th~ knownmethods reported earlier". Tnme.thylchlorosllane andtrimethylchloro-germane were dlshlled. befor~ use.

Reaction between bis(trimethyl-germamum)oxzde andboric anhydride-Boric anhydride (~·58 s. ~·83 mmole)was added to bis(trimethyl-germamum)o~lde (0·611 s.2·# mmoles). The mixture was kept aSl~e for.l h~;the white solid goes in solution slowly to give tns(tn-methyl-germyl)borate, which distiI;> at 75°/6

0mm

(Found: B, 2·8. C9Hz70BGea requrr es B, 2'610)·.Reaction bettuee» tris(tributyl-stannyl)borate and tri-

methylchlorosilane -:- An exother~ic reaction wasobserved when trimethylchlorosilane (1·00 g, 9·21mmoles) was added drop by drop to trisJtr.ibutxl-stannyl)borate (2·42 g,. 2·6.1 mmole~). DIstillationof the mixture gave trisjtrimethyl-silyljborate, !>.p.62-64°/6 mrn (0'42 g, 49% yield) as th~ first fraction;tributyl-tinchloride (2'52 g, 98% YIeld) appearedas the second fract ion at 97%'3 mm.

Reaction betseee» tris(tributyl-stannyl) borate andtrimeihylchlorogermane - Trirnethylchloro - germane(1·07 g, 7·05 mmoles) was added drop by drop totris(tributyl-stannyl)bor~te (?-'~7 s. 2·23 m~oles).Reaction was exothermic, distillation gave trisjtri-methylgermyljborate, b.p. 78°/6 ~m (0,49. g, 53%)as the first fraction and tributyl-tin chloride as thesecond fraction, b.p. 100%.3 mm (1·86 g, 85% yield).

One of the authors (S.K.M.) is grateful to the UGC,New Delhi, for financial support.

References

1. STEINBERG,H., Organoboron chemistry, Vol. I (John Wiley.New York), 1964, Ch. XIII.

2. ABEL, E. W. & SINGH, A., ]. chem . Soc., (1959), 690.3. MEHROTRA,S. K .• SRIVASTAVA,G. & MEHROTRA,R. C.,

]. organometal . Chem., 73 (1974), 277.4. Inorganic polymers, edited by F. G. A. Stone & W. A.

Graham (Academic Press, New York).• 1962. .5. S. K. MEHROTRA,Ph.D. thesis, University of Rajasthan.

]aipur, 1973.6. MEHROTRA,S. K., SRIVASTAVA,G. & MEHROTRA,R. C.,

]. organometal . cu«; 65 (1974), 361.7. BROWN, ]. 1\1., CHAPMAN,A. C., MOWTHROPE,D. ].,

DAVIES, A. G. & SMITH, P. ]., ]. chem. Soc. Dalton.(1972), 338.

138

Double Isopropoxides of Hf(IV) with AlkalineEarth Metals

(:\Iiss) S. GOV,L & R. C. MEHROTRA*Department of Chemistry, University of Rajasthan

]aipur 302004

Received 2 June 1975

Volatile double isopropoxldes, M[Hfl(OPrl)]s. andMHf3(OPrl)w have been synthesized by the reaction ofhafnium isopropoxide isopropanolate and alkaline earthmetals in different stoichiometric ratios.

A NUMBER of volatile double alkoxides of haf-nium with alkali metals, aluminium and gallium

were synthesized in o,:!r labora.tories1. These doublealkoxides are soluble III organic solvents. However.alkoxides of alkaline earth metals and magnesiumare insoluble in organic solvents and in view of this,it was considered of interest to make a study of doublealkoxides of hafnium with these metals.

Alkaline earth metal isopropoxides are insoluble inisopropanol, and the rate of dissolution of these isopro-poxides is extremely slow in the alcohol even in the pre-sence of mercuric chloride catalyst. The rate of dis-solution is markedly enhanced by the addition of haf-nium isopropoxide, yielding finally double isopropoxi-des which are soluble in isopropanol and can be vola-tilized without decomposition under reduced pressure.

Products of the type M[Hf2(OPri) 9]2 have beensynthesized by dissolvi.ng t~e alkalin.e e~rth metalsin the solution of hafnium isopropoxide isopropano-late, Hf(OPri)4 PriOR, in isopropanol in 1:4 molarratio in accordance with Eq. (1).

PriOHM+4Ht(OPri)4PriOH ---~ M[Hf2(OPri)9J2+H2 t

HgCl2 (I)

'" (1)(M = Mg. Ca, Sr or Ba)

Catalytic amount of mercuric chloride was usedto facili.tate the reaction.

All these products are white crystalline solids,soluble in isopropanol, benzene and in common or-ganic solvents. These could be purified by recry-stallization from isopropanol or by sublimation!distillation under reduced pressure.

Molecular weights of magnesium and calcium, deri-vatives were determined in benzene; the former showsmonomeric behaviour while the later is dimeric,

Reactions of alkaline earth metals with Hf (OPri)4'PriOH in 1 :3 molar ratio in isopropanol in the pre-sence of small amount of HgCl2, resulted in the for-mation of the product, MHf3(OPri)14 (Eq. 2).

PriOHM+3Hf(OPri)4·PriOH ----+ MHf3(OPrih4 +H2 t .-

HgClz...(2)

(M = Mg, Ca, Sr or Ba)These products are also white' crystalline solids,

less soluble in isopropanol, benzene and in other com-mon organic solvents as compared to products ofthe type (I). These can be volatilized under reducedpressure. Molecular weights of II could not bedetermined due to low solubility.

-Present address: University of Delhi, Delhi 110007.