Synthesis and structures of aluminum alkanethiolate complexes

The homoleptic aluminum thiolate complex [Al(mu-S-t-Bu)(S-t-Bu)(2)](2) was prepared by reacting AlBr(3) with NaS-t-Bu while the analogous 2-propanethiolate complex [Al(mu-S-i-Pr)(S-i-Pr)(2)](2) was synthesized by reacting AlH(3)(OEt(2)) with i-PrSH. In the solid state, the dimers have tetrahedral Al atoms and anti-Al(mu-SR)(2)Al four-member rings. The attempted synthesis of [Al(mu-S-t-Bu)(S-t-Bu)(2)](2) by reacting Al(N-i-Pr(2))(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(mu-mgr;-S-t-Bu)(S-t-Bu)(2)](2) and the salt [i-Pr(2)NH(2)][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(NMe(2))(3)](2) and AlH(3)(NMe(2)Et) with the alkanethiols yielded stable amine adducts Al(SR)(3)(R'NMe(2)) (R = i-Pr or t-Bu; R' = H or Et). The ligand adducts Al(S-i-Pr)(3)(HNMe(2)) and Al(S-t-Bu)(3)(THF) have distorted trigonal pyramidal geometries in the solid state. Three of the new compounds, [Al(mu-S-i-Pr)(S-i-Pr)(2)](2) and Al(SR)(3)(HNMe(2)) (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.