Transition Metal Complexes of Chromium, Molybdenum, Tungsten, and Manganese Containing η¹(S)-2,5-Dimethylthiophene, Benzothiophene, and Dibenzothiophene Ligands

Abstract

Ultraviolet photolysis of hexanes solutions containing the complexes M(CO)6 (M = Cr, Mo, W) or CpMn(CO)3 (Cp = η5-C5H5) and excess thiophene (T*) (T* = 2,5-dimethylthiophene (2,5-Me2T), benzothiophene (BT), or dibenzothiophene (DBT)) produces the η1(S)-T* complexes (CO)5M(η1(S)-T*) 1−8 or Cp(CO)2Mn(η1(S)-T*) 9−11, respectively. However, when T* = DBT and M = Mo, a mixture of two products results, which includes (CO)5Mo(η1(S)-DBT), 4a, and the π-complex (CO)3Mo(η6-DBT), 4b, as detected by 1H NMR spectroscopy. Only the complexes (CO)5W(η1(S)-DBT) (1), (CO)5Cr(η1(S)-DBT) (5), and Cp(CO)2Mn(η1(S)-DBT) (9) were sufficiently stable (several days) to be isolated and characterized by elemental analyses. Rates of DBT ligand displacement by CO (1 atm) at room temperature decreased in the order 5 > 1 > 9. Single-crystal, X-ray structural determinations are reported for 1, 5, and 9. The tilt angle (θ) of the DBT ligand in these and related complexes is discussed in terms of π-back-bonding to the DBT ligand.

Gas-phase oon-molecule reactions of transition metal complexes: The effect of different coordination spheres on complex reactivity

“…Gas-phase studies of heterocycle coordination to metal ions show that, by itself, thiophene prefers a -interaction to form ML or ML 2 complexes instead of heteroatom bound -bond interactions [63]. On the other hand in some cases, the 1 (S) binding mode to the metal center in solution can be induced by incorporating the thiophene unit into a multidentate ligand [64]. The 1 (S) binding mode, however, is generally fairly weak.…”

Density functional theory calculations for electronic, optoelectronic and thermodynamic properties of dibenzothiophene metal complexes

“…The selected optimised parameters presented in table 1 for Cr and W complex of Dibenzothiophene show almost same values for experimental [29] and theoretical case as depicted by percentage difference values. Now to understand molecular chemical stability and the relationship of Nonlinear optical properties with the molecular structure, the HOMOs, LUMOs, and HOMO-LUMO energy gaps have been studied for both the molecules [30].…”

Coordination and Oxidative Addition at a Low-Coordinate Rhodium(I)β-Diiminate Centre

“…π Coordination has been reported or suggested for dibenzothiophene and derivatives in several cases 24b, 24h, 28, 29 . η 4 Coordination has been suggested only for [Cp*Ir(dbt)] 28a.…”

“…To our knowledge 8 is the first structurally characterised bisdibenzothiophene complex. The σ‐S bonding mode has been observed several times for dibenzothiophene24a and σ‐S‐bonded complexes have been structurally characterised for chromium,24b molybdenum,24b, 24c tungsten,24b manganese,24b, 24d rhenium,16, 24e iron,24f ruthenium24g and iridium 24h. S‐Coordination of thiophenes in oil24c, 24g and coal24f is believed to be the first step in their catalytic desulfurisation.…”