Effect of CO substitution on the redox properties of Fischer Mo(0) carbene complexes Mo(CO)5=C(Y)(2-Furyl), Y=OEt, NHCy or NH2

Structural and electronic features of triphenylstibine-functionalized Fischer carbene complexes of molybdenum(0)

“…Satisfactory resolution was obtained for the signals of the proton atoms present on the 2,2'-bithienyl moiety of 4, as only the chemical shift of H14 was observed as a broad singlet, instead of an expected doublet of doublets [12,42,43]. The phenyl-ring protons of the triphenylstibine ligand were observed as a multiplet with an integration value of 15 for 1, 2, and 4, which was also reported for the triphenylphosphine [9][10][11][12] and triphenylarsine [12] analogues. The high instability of 3 prohibited any NMR analyses of this complex.…”

“…The IR spectra of 1 -4 exhibited four stretching frequencies in the carbonyl region, suggesting a cis-tetracarbonyl system [46] for all four complexes. No distinct pattern is observed for the IR stretching frequencies of 1 -4, which are quite similar to carbonyl stretching frequencies of the PPh3-and AsPh3-subsituted analogue complexes [9][10][11][12]. Abel et al [47] also observed similar carbonyl stretching frequencies for [(EPh3)3(CO)3Mo] with E = P, As, Sb, and therefore proposed that the donor-acceptor properties of PPh3, AsPh3, and SbPh3 are too similar to cause significant variation in the carbonyl stretching frequencies [48].…”

“…Our research group expanded the field of heteroarene-based Fischer carbene complexes of Mo(0) through the incorporation of ligands such as triphenylphosphine [9][10][11][12], 1,2bis(diphenylphopshino)ethane [10,11] and triphenylarsine [12] into the coordination sphere.…”

“…The second method involves carbonyl substitution of a metal hexacarbonyl complex, and the resulting substituted pentacarbonyl complex is then subjected to carbene synthesis to yield the cis-substituted tetracarbonyl Fischer carbene complex [6]. Both of these methods have been successfully employed in the synthesis of phosphine-and arsine-substituted Fischer carbene complexes [6][7][8][9][10][11]38]. However, Fischer and Aumann [6]…”

Mo Fischer Carbene Complexes: A DFT Study on the Prediction of Redox Potentials

“…24 Substitution of carbonyl ligands reduced the oxidation potential of the complex; the mer-[(CO) 3 (dppe)Mo] carbene complex was easier to oxidize (approximately 0.6 V lower) than the pentacarbonyl Mo carbene analogue. 25 Also, ethoxy carbene complexes are more difficult to oxidize (more than 0.05 V higher) than aminocarbene complexes. 25 In this study, 23 derivatives of Mo carbene complexes are examined (Fig.…”