Synthesis and Structures of Aluminum Alkanethiolate Complexes

The homoleptic aluminum thiolate complex [Al(μ-S-t-Bu)(S-t-Bu)2]2 was prepared by reacting AlBr3 with NaS-t-Bu
while the analogous 2-propanethiolate complex [Al(μ-S-i-Pr)(S-i-Pr)2]2 was synthesized by reacting AlH3(OEt2) with
i-PrSH. In the solid state, the dimers have tetrahedral Al atoms and anti-Al(μ-SR)2Al four-member rings. The
attempted synthesis of [Al(μ-S-t-Bu)(S-t-Bu)2]2 by reacting Al(N-i-Pr2)3 with t-BuSH in THF solvent yielded the thermally
stable THF adduct Al(S-t-Bu)3(THF). The same reaction in diethyl ether solvent produced a mixture of [Al(μ-S-t-Bu)(S-t-Bu)2]2 and the salt [i-Pr2NH2][Al(S-t-Bu)4]. In the solid-state structure of the salt, the anion [Al(S-t-Bu)4]- has
a distorted tetrahedral geometry. Reactions of [Al(NMe2)3]2 and AlH3(NMe2Et) with the alkanethiols yielded stable
amine adducts Al(SR)3(R‘NMe2) (R = i-Pr or t-Bu; R‘ = H or Et). The ligand adducts Al(S-i-Pr)3(HNMe2) and
Al(S-t-Bu)3(THF) have distorted trigonal pyramidal geometries in the solid state. Three of the new compounds,
[Al(μ-S-i-Pr)(S-i-Pr)2]2 and Al(SR)3(HNMe2) (R = i-Pr or t-Bu), are viable precursor candidates for the chemical
vapor deposition of aluminum sulfide films because they are thermally stable, volatile liquids at moderate temperatures.