Inorganic Chemistry, Vol.38, No.7, 1627-1633, 1999
Synthesis and structures of gallium alkylthiolate compounds
Gallium alkylthiolate complexes have been prepared from gallium amide complexes and thiols. The amide complex [Ga(NMe2)(3)](2) reacts with excess t-BuSH to give the amine adduct Ga(S-t-Bu)(3)(HNMe2), In contrast, the bulky amide complex Ga(N-i-Pr-2)(3) reacts with t-BuSH to give the homoleptic thiolate dimer [Ga(S-t-Bu)(3)](2). The analogous reaction between Ga(N-i-Pr-2)(3) and i-PrSH produces the salt [i-Pr2NH2][Ga(S-i-Pr)(4)], which on heating under vacuum loses amine and thiol to give the dimer [Ga(S-i-Pr)(3)](2). Reactions of [i-Pr2NH2][Ga(S-i-Pr)(4)] and [Ga(S-t-Bu)(3)](2) With excess pyridine give the adducts Ga(SR)(3)(py) (R = i-Pr or t-Bu). X-ray crystallographic studies show that the dimers have two bridging thiolate ligands. The Ga(mu-SR)(2)Ga four-membered ring in [Ga(S-i-Pr)(3)](2) has a planar anti geometry while the ring in [Ga(S-t-Bu)(3)](2) has a butterfly syn configuration. In the solid state, Ga(S-t-Bu)(3)(HNMe2) and [i-Pr2NH2] [Ga(S-i-Pr)(4)] have trigonal-pyramidal and distorted tetrahedral geometries, respectively. The [Ga(SR)(3)](2) compounds exhibit solution fluxional behavior consistent with two separate processes, bridge-terminal thiolate exchange and effective inversion at the bridging sulfur atoms. Ab initio molecular orbital calculations on [Ga(SH)(2)(mu-SH)](2) at the MP4(SDQ) level predict activation energies for the two processes of 17.6 and 11.9 kcal/mol, respectively. Crystal data are as follows. Ga(S-t-Bu)(3)(HNMe2), C14H34GaNS3 at 223 K:. P2(1)/n (monoclinic), a = 9.6373(5) Angstrom, b = 12.7183(7) Angstrom, c = 16.9708(9) Angstrom, beta = 91.9810(10)degrees, and Z = 4. [i-Pr2NH2] [Ga(S-i-Pr)(4)], C18H44GaNS4 at 223 K: P2(1)/n (monoclinic), a = 12.0179(6) Angstrom, b = 15.4813(8) Angstrom, c = 14.3875(8) Angstrom, beta = 93.801(1)degrees, and Z = 4. [Ga(S-i-Pr)(3)](2), C18H42Ga2S6 at 223 K: P-1 (triclinic), a = 8.6813(8) Angstrom, b = 9.2969(8) Angstrom, c = 11.1804(10) Angstrom, alpha = 107.385(2)degrees, beta = 95.987(1)degrees, gamma = 117.285(1)degrees, and Z = 1. [Ga-(S-t-Bu)(3)](2), C24H54Ga2S6 at 223 K: C2/c (monoclinic), a = 10.0630(10) Angstrom, b = 17.698(2) Angstrom, c = 19.836(2) Angstrom, beta = 98.500(10)degrees, and Z = 4.
Keywords:MOLECULAR-STRUCTURES;THIOLATE COMPLEXES;FILMS;DEPOSITION;PRECURSORS;CRYSTAL;ELEMENTS;LIGANDS;MOCVD