The Synthesis of InP drom Indium Halides and Tris(Trimethylsilyl)Phosphine
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THE SYNTHESIS OF InP FROM INDIUM HALIDES AND TRIS(TRIMETHYLSILYL)PHOSPHINE
MATTHEW D. HEALY,
PAUL E.
LAIBINIS,
PAUL D. STUPIK AND
ANDREW R. BARRON Department of Chemistry, Harvard University,
Cambridge,
MA 02138,
ABSTRACT with
InP has been prepared by the reaction of InX 3 (X = Cl, Br, I) P(SiMe 3 ) 3 . The intermediates and product have been
characterized
XPS,
by
elemental
analysis
and
X-ray
powder
diffraction.
INTRODUCTION The technological importance of the III-V semiconductor compound indium phosphide, InP, has led to a renewed interest in the chemistry of compounds containing covalent bonds between indium and phosphorus.I One such class of compounds with the empirical formula (R2InPR' 2 ). was originally prepared by Coates et al. 25 years ago by the reaction of indium trialkyl compounds with a secondary phosphine (e.g., Reaction 1).2 Recently, Jones et al. have shown that lithium dialkyl-phosphides will react with indium halides to yield indium phosphido compounds. (Equation 2).3
3InMe 3 + 3HPMe InCl
3
2
+ 4LiPPh 2
o (Me2 InPMe 2 ) 3 + 3MeH
-
-*
Li[In(PPh2) 4] + 3LiCl
(1) (2)
Recent research in our laboratories has demonstrated that the dehalosilylation reaction is a facile route to the formation of In-P bonds (Equation 3).4 2Me 2InCl + 2Ph 2 P(SiMe 3 )
-P
Mat. Res. Soc. Symp. Proc. Vol. 131. c1989 Materials Research Society
(Me 2InPPh 2 ) 2 + 2Me 3SiCl
(3)
84
The relatively mild conditions required for this reaction,
often
room temperature prompted us to investigate the use of P(SiMe3) 3 for the preparation of polycrystalline indium phosphide.5 below
RESULTS AND DISCUSSION 6 Addition of P(SiMe 3 ) 3 (5% molar excess) to a rapidly stirred 0 toluene suspension of InCl 3 at -78 C, results in the formation of As the reaction is warmed to room tempea pale yellow solid.
Removal of all volatiles by rature the reaction mixture darkens. vacuum distillation, at room temperature yields a bright orange powder which is
The insolubility
insoluble in organic solvents.
of this material suggests
that it
may
be a polymeric
species.
XPS and elemental analysis this orange powder is proposed to be [Cl 2 InP(SiMe 3 ) 2]x (la). 0 Heating la at 550 C for 1 h yields InP (2a) as a black powder. Based on
No chlorine or silicon is
detected by XPS or elemental analysis.
In survey spectrum of the InP is shown in Figure 1. addition to peaks due to the In and P, peaks arising from 0 and C A typical
are observed.
They are possibly due to the native oxide and some
The X-ray inadvertent carbon contamination due to air exposure. powder diffraction confirms the product to be primarily poly6 crystalline indium phosphide. The thermogravometic
analysis of la is
loss of two equivalent of Me3SiCl.
at ca 1100 C, the maximum decomposition rate conversion of la to InP is
consistent with the decomposition occurs
Initial
is
0 above 410 C.
The
complete at 5600C.
The reaction of P(SiMe 3 ) 3 with InBr 3 proceeds analogously. dark
orange
intermediate
(1b),
as
formulated
0 decomposes comple
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