Methylenetriimidosulfate H2 CS(NtBu)32- -The First Dianionic Sulfur(VI) Ylide

Angew Chem Int Ed Engl. 2001 Oct 15;40(20):3846-3849. doi: 10.1002/1521-3773(20011015)40:20<3846::AID-ANIE3846>3.0.CO;2-3.

Abstract

Through isoelectronic replacement of the oxygen atoms in SO42- ions by one CH2 and three NtBu groups one arrives formally at the dianion H2 CS(NtBu)32- , which has been isolated for the first time in the form of the sulfur(VI) ylide complex [(tmeda)2 Li2 {CH2 S(NtBu)3 }]. Deprotonation of the S-bonded methyl group in the triimidosulfonate MeS(NtBu)3- ion provides facile access in good yields. Hydrolysis favors the formation of the triimidosulfate [{(tmeda)Li2 [OS(NtBu)3 ]}3 ] and methane, and not, as one might expect, diimidomethylenesulfate and the amine. tmeda=Me2 NCH2 CH2 NMe2 .

Keywords: S ligands; bond theory; carbanions; lithium; ylides.