The crystal structure of dicyclopentadienylvanadium monochloride and its implications for the structures of other d2 dicyclopentadienyl compounds

A New Versatile Approach to Substituted Cyclopentadienyl−Cycloheptatrienyl Complexes of Zirconium (Trozircenes)

“…The deviations of the aromatic ligand planes from parallel orientations increase on Lewis base coordination, to 33.0° for Zr(C 7 H 7 )(C 5 H 4 SiMe 3 )(THF) and 31° for Zr(C 7 H 7 )(C 5 H 5 ){CN[2,6-C 6 H 3 (CH 3 ) 2 ]}. The closely related angles between the M−centroid vectors are 148.9° and 149.3°, respectively, which seem somewhat large relative to complexes such as V(C 5 H 5 ) 2 Cl (139.5°), which may be attributed to the previously discussed closeness of the C 7 H 7 ligand to the metal. This close approach is also likely responsible for greater angles between the M−C 7 H 7 centroids and the THF or isocyanide ligands (113.9° and 112.7°), as compared to the corresponding angles involving the Cp ligand (97.1° and 98.0°).…”

A π-Donor Spectrochemical Series for X in (Me5C5)2TiX, and β-Agostic Interactions in X = Et and N(Me)Ph

“…The best known bonding model for bent metallocenes is due to Lauher−Hoffmann; Figure shows the metallocene orbitals with two different coordinate systems. − The coordinate system used here, due to Petersen and Dahl, is more convenient because this coordinate system minimizes the mixing the d z 2 and d x 2 - y 2 orbitals. , This metallocene bonding model is supported by the work of Petersen and Dahl in which single-crystal EPR spectroscopy shows that the single electron in (η 5 -MeC 5 H 4 ) 2 VCl 2 and Cp 2 VS 5 occupies an orbital that is perpendicular to the plane formed by the metal and the two Cp centroids and is largely of d z 2 parentage (in this coordinate system). , In Cp* 2 TiX, the unpaired electron resides in the low-lying a 1 orbital which is largely d z 2 . The empty b 2 orbital can interaction with the p z orbital of the X ligand to form a π-bond and a π-antibond; the latter is the b 2 orbital.…”

Electron-transfer reactions of metallocenes. Influence of metal oxidation state on structure and reactivity

“…The anion of unsubstituted manganocene has not been detected,40 but that of bis(j75-pentamethylcyclopentadienyl)manganese has been. 47 The general shape of Table III is triangular, peaking at the d6 configuration known to be so stable in metal compounds. £ 1 /2 values for the ^M1 reductions were shown21 to correlate with the second metal ionization potentials for = Cr, V, Co, and Ni.…”