Synthesis and crystal structures of [C6H4SC(S)NNa·3P(NMe2)3O·NaN(S)CSC6H4] and [C6H4SC(S)NLi·pmdien](pmdien =N,N,N′,N″,N″-pentamethyldiethylenetriamine): alkali-metal amides from 2-sulfanylbenzothiazole

Abstract

Reaction of 2-sulfanylbenzothiazole with MBuⁿ(M = Li or Na) in the presence of the Lewis-base donors Me₂NCH₂CH₂NMeCH₂CH₂NMe₂(pmdien) and P(NMe₂)₃O gave, respectively, the monomer [[graphic omitted]Li·pmdien] and the dimer [[graphic omitted]Na·3P(NMe₂)₃O·Na[graphic omitted]H₄], the structures of which have been determined by X-ray crystallography. In common with other structurally characterised sulfanylbenzothiazolate complexes, both the five-co-ordinate metal cations are involved in bridged bonding with the exocyclic S and the amido N. The amido N⁺–M^– is the formal bond making these two structures amide rather than thiolate complexes. In the sodium complex this is clear [N-Na 2.46(1)Å], however, in the lithium case the Li-N bond is exceptionally long [amido N-Li 2.14(1)Å], but an analysis of the bond lengths within the sulfanylbenzothiazolate moiety verifies its amido nature. The two complexes also show rare secondary bonding of the exocyclic S atoms by the alkali-metal cations, exo-S–Li 2.73(1) and exo-S–Na 2.995(1) and 2.951(7)Å.