PADDLE-WHEEL AND TRILOBATE ISOMERS OF THE HEXAGONAL PRISMS (LI[CE(NT-BU)(N-BU)])6 (E = S, O)

Current interest in isoelectronic analogues of carboxylate anions RCO2 - (1a) such as amidinates RC(NR')(2)(-) (1b) focuses on the ability of these tunable ligands to generate unusual structures and/or reactivit y in both main group and transition-metal chemistry.(1-4) The structur es of lithiated oxoamidate anions [RC(O)(NR')](-) (1c) are germane for studies of deprotonated oligopeptides.(5) The thioamidate anions [RC( S)(NR')](-) (1d) are especially interesting ligands since they combine both hard (N) and soft (S) donor centers. Surprisingly, however, only a few transition-metal complexes of this anion are known and none of them were prepared from 1d by metathetical reactions.(6) Alkali-metal derivatives of 1d are unknown.