Access to new Janus head ligands: linking sulfur diimides and phosphanes for hemilabile tripodal scorpionates

Abstract

Reactions of lithium dialkyl/phenyl phosphanylmethylides, RR'PCH(X)Li (R, R' = Me, Et, Ph and R = Me, R; = Ph; X = H or Me), with sulfur diimides S(NR '')(2) (R '' = (t)Bu or SiMe(3)) in an equimolar ratio yielded Janus head complexes with the structural motif [Li{RR'PCH(X)S(NR '')(2)}](2) (R '' = (t)Bu, SiMe(3)). The basic core of these dimeric complexes is composed of a (LiN)(2) four-membered ring containing two four-coordinated lithium atoms. A lithium complex of the new Janus head ligand with another structural motif [TMEDA center dot Li{Ph(2)PCH(2)S(NSiMe(3))(2)}] (6) could be isolated from the reaction of [Ph(2)PCH(2)Li center dot TMEDA] with S(NSiMe(3))(2). Two monomeric complexes [Mg{Me(2)PCH(2)S(NR '')(2)}(2)] (7, 8) were synthesised by a straightforward reaction of [Li{Me(2)PCH(2)S(NR '')(2)}(2)] with MgCl(2) in pentane. The magnesium atom is chelated by one phosphorus atom and two nitrogen atoms of each unit of the hemilabile ligand in a tripodal manner, leading to octahedral geometry around the magnesium cation. A complete analysis of [Ph(2)PCH(2)(SNSiMe(3))(HNSiMe(3))] (9) is also described in which one nitrogen atom of the imido moiety is protonated.