Reactions of Di(1-cyclohepta-2,4,6-trienyl)sulfane, S(C7H 7)2, with derivatives of the hexacarbonyls, M(CO) 6 (M = Cr, Mo, W)

Article abstract of DOI:10.1002/zaac.200400196

Mononuclear carbonylmetal complexes of chromium, molybdenum and tungsten containing the sulfane S(C₇H₇)₂ (1) have been obtained starting from precursors such as the THF-stabilized pentacarbonylmetal fragments, [M(CO)₅](thf), the acetonitrile intermediates M(CO) _6-x(CH₃CN)_x (x = 1, 2, 3) (M = Cr, Mo, W) or the η⁴-norbornadiene complexes M(CO)₄(C ₇H₈) (M = Cr, Mo). In addition to the pentacarbonyls, M(CO)₅[S(C₇H₇)₂] (M = Cr (2a), Mo (2b), W (2c)) which contain 1 unchanged as a two-electron sulfane ligand with two pending cyclohepta-2,4,6-trienyl substituents, isomeric complexes M(CO) ₅[S(CH₂Ph)(C₇H₇)] (M = Cr (3a), W (3c)) were obtained at higher temperatures (40-50°C) in which one of the two organic groups has been transformed into a benzyl substituent. In the tetracarbonyls, cis-M(CO)₄[S(C₇H₇) (η²-C₇H₇)] (M = Mo (4b), W (4c)), the ligand 1 serves as an olefinic sulfane four-electron chelate ligand. The reaction of either Mo(CO)₆ or (mesitylene)Mo(CO)₃ with S(C₇H₇)₂ (1) in boiling THF leads to the sulfur-free ditropyl complex Mo(CO)₃[(η⁶-C ₇H₇)-C₇H₇] (5b, two isomers). The ¹H and ¹³C NMR spectra of the new complexes 2-4 reveal various dynamic processes including pyramidal inversion of the sulfur atom and [1,7]-sigmatropic shifts at the C₇H₇ ring. The molecular structures of 2c, 3a, 4b and 4c have been determined by X-ray crystallography.