ChemInform Abstract: Raman Spectroscopic Investigation and Coordination Behavior of the Polyimido SVI Anions [RS(NR)3]- and [S(NR)4]2-.

Abstract

On the basis of Raman spec- troscopic experiments and the computa- tional assignment of the SN vibrations to small wavenumbers (640 - 920 cm ˇ1 ), the bonding in sulfur triimides is inter- preted to be mainly electrostatic (> S +ˇN 7ˇ) rather than covalent (S(aNR)3). The coordination of the S- alkyldiiminosulfonamide (RS(NR')3) ˇ and tetraazasulfate (S(NR)4) 2ˇ to bari- um is elucidated. In the anions present- ed here the central sulfur atom adopts the oxidation state vi. They can be readily synthesized from sulfur tri- imides, by nucleophilic addition of orga- nolithium species or lithium amides to the SaN formal double bond. Although three or four nitrogen donor centers are present, tripodal coordination to barium was not observed in any case. In the (S(NtBu)3) 2ˇ dianion, tripodal coordina- tion is facilitated by all tert-butyl groups pointing towards the lone pair of the sulfur atom, leaving all lone pairs of the nitrogen atoms pointing in the opposite direction. However, in ((thf)2Ba- {(NtBu)3SMe}2 )( 4) the steric demand of the S-methyl group in the (MeS- (NtBu)3) ˇ ion forces one tert-butyl group to the open site of the anion, and the third nitrogen atom is blocked. Within the (S(NtBu)4) 2ˇ ion in ((thf)4Ba2{N- (SiMe3)2}2{(NtBu)4S}) (7), tripodal coor- dination to barium is precluded by the bent SNtBu arrangement. In the known isoelectronic complex (Li2{(N- tBu)4W}2) with a linear WNtBu group tripodal coordination was observed.