A comparison of C-F and C-H bond activation by zerovalent ni and pt: a density functional study.

Density functional theory indicates that oxidative addition of the C-F and C-H bonds in C6F6 and C6H6 at zerovalent nickel and platinum fragments, M(H2PCH2CH2PH2), proceeds via initial exothermic formation of an eta2-coordinated arene complex. Two distinct transition states have been located on the potential energy surface between the eta2-coordinated arene and the oxidative addition product. The first, at relatively low energy, features an eta3-coordinated arene and connects two identical eta2-arene minima, while the second leads to cleavage of the C-X bond.

An unprecedented alpha-C-C agostic interaction in a cyclopropyl tris(pyrazolyl)boratoniobium complex.

Structural, spectroscopic and theoretical evidence indicate that an unusual alpha-C-C agostic interaction is preferred over both alpha- and beta-C-H agostic alternatives in the title compound, TpMe2NbCl(c-C3H5)(MeCCMe).

Crystallographic investigation of the role of aspartate 95 in the modulation of the redox potentials of Desulfovibrio vulgaris flavodoxin.

The side chain of aspartate 95 in flavodoxin from Desulfovibrio vulgaris provides the closest negative charge to N(1) of the bound FMN in the protein. Site-directed mutagenesis was used to substitute alanine, asparagine, or glutamate for this amino acid to assess the effect of this charge on the semiquinone/hydroquinone redox potential (E(1)) of the FMN cofactor. The D95A mutation shifts the E(1) redox potential positively by 16 mV, while a negative shift of 23 mV occurs in the oxidized/semiquinone midpoint redox potential (E(2)).