Synthesis and structural studies on thioimides, R2C=NSR and sulfur diimides, R2C=NSN=CR2.

Reaction of Ph(2)C=O and py(2)C=O with Li[N(SiMe(3))(2)] and ArSCl (Ar = 2-O(2)NC(6)H(4), 2,4-(O(2)N)(2)C(6)H(3)) yielded Ph(2)C=NSAr (1a and 1b respectively) and py(2)C=NSAr (2a and 2b respectively). Reaction of fluorenone, C(12)H(8)C=O with Li[N(SiMe(3))(2)] and ArSCl under similar conditions afforded C(12)H(8)CNSAr (3a and 3b respectively). Whilst reaction of fluorenone with Li[N(SiMe(3))(2)] and SCl(2) in a 2 : 2 : 1 ratio afforded the sulfur-diimide, C(12)H(8)CNSNCC(12)H(8) (4), reaction of py(2)C=O with Li[N(SiMe(3))(2)] and SCl(2) under similar conditions afforded the thiazyl heterocycle [py(2)CNS]Cl (5) via intramolecular coordination. The structures of 1a, 1b, 2a, 2b, 3a, 3b and 4 are determined by X-ray diffraction. In the case of 4, bond lengths and DFT studies reveal greater π-delocalisation than in 1-3.