Reactions of Di(1‐cyclohepta‐2, 4, 6‐trienyl)sulfane, S(C₇H₇)₂, with Derivatives of the Hexacarbonyls, M(CO)₆ (M = Cr, Mo, W)

Abstract

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(C7H8) (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‐C7H7)‐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.

Synthesis and Structures of Base-Stabilized Cationic Silanethionetungsten Complexes and Reaction with MeOH

“…The contribution of sp 2 hybridization to Si in 6a is also suggested by the planarization of the Si atom (the sum of the C–Si–C and C–Si–S bond angles: 337.9(1)° in 6a , 328.8(1)° in 5a ). Strong coordination of DMAP to the silicon center is demonstrated by the relatively short Si–N bond distance (1.840(3) Å) compared with those reported for nitrogen-to-silicon coordination bonds (1.83–1.94 Å). , The W–S bond distance in 6a (2.5464(9) Å) is within the range of known sulfur-to-tungsten coordination bond distances (2.51–2.58 Å); however, it is also identical to those of sulfanyl complex 5a and other structurally resembled complexes to 5a . , Thus the nature of the W–S bond in 6a appears to be a mixture of a single and a dative bonding.…”

1‐Cyclohepta‐2,4,6‐trienyl‐selanes—a77Se NMR study: Indirect nuclear77Se13C spin–spin coupling constants and application of density functional theory (DFT) calculations

“…The organoselenium compounds considered for the calculations. 53 However, a quantitative study was not carried out, since according to qualitative observations, the dynamic processes were different for identical samples depending on the time after preparation of the solutions and on the storage temperature. This means that decomposition products catalyse dynamic intra-and intermolecular processes.…”