Synthesis and crystal structures of [C6H4SC(-S)-NNa center dot 3P(NMe(2))(3)O center dot NaN-(S-)CSC(6)H4] and [C6H4SC(-S)-NLi center dot pmdien] (pmdien=N,N,N',N'',N''-pentamethyldiethylenetriamine): Alkali-metal amides from 2-sulfanylbenzothiazoles

Reaction of 2-sulfanylbenzothiazole with MBu(II) (M = Li or Na) in the presence of the Lewis-base donors Me(2)NCH(2)CH(2)NMeCH(2)CH(2)NMe(2) (pmdien) and P(NMe(2))(3)O gave, respectively, the monomer [C6H4SC(- S)- NLi . pmdien] and the dimer [C6H4SC(- S)- NNa . 3P(NMe(2))(3)O . NaN -(S -)CSC6H4], 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) Angstrom], however, in the lithium case the Li-N bond is exceptionally long [amido N-Li 2.14(1) Angstrom] 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) Angstrom.