Organometallics 1992, 11, 226-231
226
Synthesis, Structural Characterization, and Reactivity of (Me,CCH,),GaAs(SiMe,),Ga(CH,CMe,),CI, [(Me,CCH,),GaAs(SiMe,),],, and (Me,CCH,),Ga(CI)*As(SiMe,), Richard L. Wells," Andrew T. McPhail, James W. Pasterczyk, and Abbas Alvanipour Department of Chemistry, Paul M. Gross Chemical Laboratory, Duke Universify, Durham, North Carolina 27706 Received July 1, 1991
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Reaction of 2 equiv of (Me3CCH2),GaC1 with (Me3Si),As affords (Me3CCHz)zGaAs(SiMe3)zGa(CH2CMe3),C1(l),the fourth example of a compound containing the Ga-As-Ga-X (X = C1, Br) core, but the fmt wherein the organogallium four-membered ring with arsenic/halogen mixed bridging is not puckered. Compound 1, as well as (Me3CCH2),GaC1,reacts with LiAs(SiMe3),.2THF,(1:1 mole ratio) to produce the (2), which on reaction with (Me3CCH2)2GaCl(1:2 mole ratio) common product [(Me3CCH2)zGaAs(SiMe,)z]z gives 1 quantitatively. Mixing (Me3CCHJ2GaC1 and (Me3Si),As in a 1:l mole ratio yields the adduct (Me3CCH2)zGa(C1)As(SiMe3)3 (3). Thermolysis of 3 did not afford 2, nor did its reaction with an additional 1 equiv of (Me3CCH2),GaC1lead t o 1 as the predominate product. Various physical and spectroscopic characterization data are presented for compounds 1-3, as well as the results of their X-ray crystal structure determinations. Crystal data: 1, monoclinic, space group P2Jc (C5,J, a = 12.412 (1)A, b = 17.306 (1) A, c = 20.238 (2) A, @ = 119.34 (l)",V = 3790 (1) A3, Z = 4; 2, monoclinic, space group P2/c (C4,,J,.a = 12.180 (1)A, b = 12.744 (1)A, c = 19.618 (2) A, /3 = 128.43 (l)",V = 2386 (1) A3,Z = 2; 3, monoclinic, space group P2,lc (C5,J, a = 12.486 (1) A, b = 12.544 (1) A, c = 19.985 (2) A, @ = 101.73 (l)",V = 3065 (1)'43, z = 4.
Introduction Recent work in our research group involving t h e formation of gallium-arsenic bonds has resulted i n t h e r
preparation of t h e novel ring compounds PhzGaAs(SiMe3)zGa(Phz)X ( X
,
= C1 (4),lp2 Br (5Y) a n d i
(Me3SiCH,),GaAs (SiMe,),Ga( CH,SiMe3) $1 (6),3 as well as t h e d i m e r s [ P ~ , G ~ A S ( S ~ M( ~7 ~) ' )~~~and ] ~ [ (Me,SiCH2)2GaAs(SiMe3)z]z I n addition, we very recently reported the isolation of t h e indium-arsenic4 and indium-phosphorus5 analogues of 6 and 8,
,
(Me3SiCH2)zInAs(SiMe3)21n(CH2SiMe3)zCl and [(Me3,
SiCHz)zInAs(SiMe3)2]2,and (Me3SiCHz)21nP(SiMe3)zInI
(CH2SiMe3),C1 a n d [ (Me3SiCHz)zInP(SiMe3)z]z, respectively. As part of a continuing effort to expand t h e scope of the gallium-arsenic series, t h e neopentyl group was chosen as the alkyl substituent on the gallium atoms with the expectation that its different steric bulk might manifest itself in a different ring conformation or size in comparison t o t h a t of t h e previously studied (trimethylsily1)methyl group. We also sought t o investigate more fully t h e reactivity a n d interconvertibility of these types of compounds. W e present herein our results obtained with t h e neopentyl ligand system.
Experimental Section General Considerations. All manipulations and reactions were performed under vacuum, under argon in a Vacuum Atmospheres HE-493 Dri-Lab, or under Nz in standard Schlenk apparatus. Solvents were distilled from sodiumjbenzophenone ketyl under dry Nz and degassed by several freeze-pump-thaw (1) Wells, R. L.; Holley, W. K.; Shafieezad, S.; McPhail, A. T.; Pitt, C. G. Phosphorus, Sulfur Silicon Relat. Elem. 1989,41, 15. (2) Holley, W. K.; Wells, R. L.; Shafieezad, S.; McPhail, A. T.; Pitt, C. G. J. Organomet. Chem. 1990, 381, 15. (3)Wells, R. L.; Pasterczyk, J. W.; McPhail, A. T.; Johansen, J. D.; Alvanipour, A. J. Organomet. Chem. 1991,407, 17. (4) Wells, R. L.; Jones, L. J.; McPhail, A. T.; Alvanipour, A. Organo-
metallics 1991, 10, 2345. (5) Wells, R. L.; McPhail, A. T.; Self, M. F. Organometallics, in press.
0276-733319212311-0226$03.00/0
cycles. (Me3CCH2)2GaC1,G (Me3Si)3As,7and LiAs(SiMe3),.2THF7 were prepared by literature procedures. 'H (300 MHz) and l%(lH) (75.4 MHz) NMR spectra were recorded on a Varian XL-300 spectrometer at ambient temperatures using C6D6 or C7Dssolutions in 5-mm tubes which were flame-sealed under vacuum and were referenced to TMS using the residual protons or the carbons of deuterated benzene a t 6 7.15 or 128 ppm, respectively, or the upfield pentet of C7Dsat 6 2.09 ppm for 'H NMR spectra Melting points (uncorrected) were obtained with a Thomas-Hoover Uni-melt apparatus, and capillaries were flamesealed under argon. Crystals used in the X-ray analyses were flame-sealed in 0.7-mm thin-walled glass capillaries. Elemental analyses were performed by E+R Microanalytical Laboratory, Inc., Corona, NY. , Preparation of (Me3CCHz),GaAs(SiMe&Ga(CH2CMe3)zCl (1). Reaction of (Me3CCH2)2GaCl with (Me3Si)3As (2:l Mole Ratio). (Me3CCH.JZGaCl(0.247 g, 1.00 "01) in 20 mL of benzene and (Me3Si)3As(0.147 g, 0.500 mmol) in 5 mL of benzene were combined in a 100-mL one-necked round-bottomed flask equipped with a Teflon valve and a magnetic stirbar. After one freeze-pump-thaw cycle of the solution, followed by stirring at room temperature for 5 days, removal of the volatiles in vacuo afforded a crude product which was dissolved in a small amount of pentane. When the solution stood overnight at -15 "C, a very small amount of white material (mp 170 "C dec; 'H NMR (C&) 6 0.53 ( 8 , 18 H, &Me3), 1.32 ( ~ , 9H, cMe3), 1.42 (s,2 H, CH,)) precipitated from the pentane solution, and after filtration and concentration, cooling the mother liquor to -15 OC afforded colorless crystals of 1 suitable for X-ray analysis (0.14 g, 41% yield); mp 70-110 "C dec. Anal. Calcd (found) for Cz6HBZAsC1Ga2Siz: c, 45.87 (45.74); H, 9.17 (9.27). 'H NMR (CsD6): 6 0.45 (9, 18 H, sikfe3),1.27 (9, 36 H, CMe3),1.38 (9, 8 H, CHz). 13C(lH)NMR (CeD6): 6 4.71 (s%fe3),32.92 (Me&), 34.50 (Me3C),40.57 (CH,). Preparation of [(Me3CCH2)2GaAs(SiMe3)2]~ (2). (a) Reaction of (Me3CCH2),GaCl with L ~ A S ( S ~ M ~ , ) ~ - ~AdTHF. dition of a solution of L ~ A S ( S ~ M ~ , ) ~ -(0.283 ~ T H g, F 0.800 mmol) in 10 mL of benzene to a solution of (Me3CCHJZGaCl(0.200 g, 0.800 mmol) in 20 mL of benzene contained in a 100-mL onenecked round-bottomed flask equipped with a Teflon valve and a microstirbar gave a light brown reaction mixture which was stirred at room temperature for 24 h. Removal of the benzene
.
( 6 ) Beachley, 0. T.; Pacik, J.
C. Organometallics 1988, 7, 1516. (7) Becker, G.; Gutekunst, G.; Wessely, H. J. Z. Anorg. Allg. Chem. 1980,462, 113.
0 1992 American Chemical Society
Organometallics, Vol. 11, No. 1, 1992 227
Gallium-Arsenic Compounds
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Table I. Crystallographic Data and Measurementsa for (Me3CCH2)zGaAs(SiMe3)2Ga(CH&Me3)2C1 (l), [(Me3CCHz)2GaAs(SiMe3)2]2 (2), and (Me3CCH2)zGa(CI)As(SiMeA (3) 1
mol formula fw
cryst syst space group a, A
b, A
c,
A
8, deg no. of orientn rflns; 8 range, deg
v, A3
Z
Dcalcd,
g Cm-'
temp, "C cryst dimens, mm Tmsx:Tmin
radiation (wavelength, A) p , cm-' scan type scan width. deg 4" deg intens control rflns variation, %; repeat time, h no. of rflns recorded no. of nonequiv rflns recorded Rmerge (on no. of rflns retained, Z > 3.0u(n no. of params refined extinction cor R (RJ* goodness of fit' max shift/esd in final least-squares cycle final max, min Ap, e A-3 .
I
n
C26Hs2AsC1Ga2Si2 685.97 monoclinic P2dc (C52h) 12.412 (1) 17.306 (1) 20.238 (2) 119.34 (1) 25; 42-48 3790 (1) 4 1.202 25 0.40 X 0.50 X 0.60 1.W0.68 Cu K a (1.5418) 43.0 w-28 1.10 + 0.14 tan 8 75 i5i,34i, 126,208 c2; 2 8216 (+h,+k,U) 7775 0.026 6153 290 [8.1 (311 X 0.045 (0.065) 2.36 0.02 0.75, -0.69
2
3
C32H&s2Ga2Si4 866.62 monoclinic P 2 / c (C42h) 12.180 (1) 12.744 (1) 19.618 (2) 128.43 (1) 25; 42-48 2386 (1)
ClgH4&C1GaSi3 541.96 monoclinic P 2 , / c (C52h) 12.486 (1) 12.544 (2) 19.985 (1) 101.73 (1) 25; 45-48 3065 (1) 4 1.174 25 0.40 X 0.50 X 0.60 1.00:0.61 Cu K a (1.5418) 44.1 w-28 1.10 + 0.14 tan 8 75 224, 224, 224, 224
