Crystal structures of two closely related compounds of molybdenum-(II) and -(IV): carbonylcyclopentadienylhexafluorobut-2-yne(pentafluorophenylthio)molybdenum and cyclopentadienyl(hexafluorobut-2-yne)oxo(pentafluorophenylthio)molybdenum

Oxo Ligand Reactivity and Bonding in the Dinuclear W−Re Oxo−Acetylide Complex (η5-C5Me5)W(O)Re(CO)4(μ-H)(CCPh)

“…In addition, the acetylide π-bond is virtually perpendicular to the W−O vector with angles O(5)−W−C(5) = 110.1(2)° and O(5)−W−C(6) = 104.0(2)°. This overall molecular geometry closely resembles that observed for the complexes CpMo(O)(PhC 2 Ph)(Ru(CO) 2 Cp), CpW(O)(HC 2 Ph)(CH 2 CO 2 Et), and CpMo(O)(CF 3 C 2 CF 3 )(SC 6 F 5 ) owing to the maximization of the metal-to-acetylide back bonding and the dative π-interaction from the terminal oxo ligand to the central metal atom.…”

Reactions of Tetracyclone Molybdenum Complexes with Electrophilic Alkynes: Cyclopentadienone–Alkyne Coupling and Alkyne Coordination

“…A more obvious difference is the reorientation of the alkyne ligand so that it is now perpendicular to the MoO bond: i.e., it has rotated by 90° in comparison to its position in the carbonyl complex 3 , due to competition for the available metal d orbitals with the strong π-donor oxo ligand. The same reorientation of the alkyne ligand was shown to have taken place in the X-ray crystal structures of two related complexes, [Mo­(CO)­(SC 6 F 5 )­(F 3 CCCCF 3 )­(η-C 5 H 5 )] and [Mo­(O)­(SC 6 F 5 )­(F 3 CCCCF 3 )­(η-C 5 H 5 )], and the alkyne in [W­(O)­(Ph)­(PhCCPh)­(η-C 5 H 5 )] also adopts the same geometry …”

“…The X-ray crystal structure of 8 is shown in Figure , with important bond lengths detailed in the caption. The MoO distance of the terminal oxo ligand is 1.693(5) Å, which is typical for Mo­(IV) oxo complexes of this type . Whereas the bonds between Mo and the four former diene carbons C(8)–C(11) are equal within experimental error, that to the oxygen-bearing carbon C(7) is now significantly shorter than in complex 3 .…”

Thiolates vs. halides as π-donors: the redox-active alkyne complexes [M(SR)L(η-R′CCR′)L′] {M = Mo or W, L = CO or P(OMe)3, L′ = η-C5H5 and Tp′}

“…the syn isomer with R orientated towards the h-C 5 H 5 ring or Tp¢ ligand and the anti isomer with R pointing toward the carbonyl and alkyne ligands) and as seen for [Mo(SC 6 F 5 )(CO)(h-CF 3 C≡CCF 3 )(h-C 5 H 5 )]. 5 It is notable that the relative intensities, and therefore presumably the isomer distribution in solution, are very different for the…”

“…During a study of the stepwise conversion of the (formally) d 5 alkyne complexes [M(CO) 2 (h-RC≡CR)Tp¢] {Tp¢ = hydrotris (3,5-dimethylpyrazolyl)borate} to the d 2 cations [MX 2 (h-RC≡CR)Tp¢] + (M = Mo or W, X = F or Cl) via a sequence of one-electron transfer and substitution reactions, 1-3 we observed that the dependence of both the oxidation potential and n(CO) of [MX(CO)(h-RC≡CR)Tp¢] (in the order X = F < Cl < Br < I, i.e. an inverse halide order) was consistent with an ionic component to the M-X bond.…”