The first phosphinidene complexes of scandium are reported in this contribution. When complex (PNP)Sc(CH(3))Br (1) is treated with 1 equiv of LiPH[Trip] (Trip = 2,4,6-(i)Pr(3)C(6)H(2)), the dinuclear scandium phosphinidene complex [(PNP)Sc(mu(2)-P[Trip])](2) (2) is obtained. However, treating 1 with a bulkier primary phosphide produces the mononuclear scandium ate complex [(PNP)Sc(mu(2)-P[DMP])(mu(2)-Br)Li] (3) (DMP = 2,6-Mes(2)C(6)H(3)). The Li cation in 3 can be partially encapsulated with DME to furnish a phosphinidene salt derivative, (PNP)Sc(mu(2)-P[DMP])(mu(2)-Br)Li(DME)] (4). We also demonstrate that complex 3 can readily deliver the phosphinidene ligand to organic substrates such as OCPh(2) and Cl(2)PMes* as well as inorganic fragments such as Cp(2)ZrCl(2), Cp*(2)TiCl(2), and Cp(2)TiCl(2) in the presence of P(CH(3))(3). Complexes 2-4 have been fully characterized, including single crystal X-ray diffraction and DFT studies.

Collision of H(2) with the unusual nickel complex, (PNP)Ni(+), where PNP = ((t)Bu(2)PCH(2)SiMe(2))(2)N, forms a rare dihydrogen complex of the d(8) configuration which then rearranges to heterolytically cleave the H-H bond. Experimental studies support a short H/H distance in the coordinated diatomic, and DFT calculations show that the transition state for heterolysis, in spite of the fact that this involves an amide nitrogen located trans to the H(2), has the H/H bond fully split, and has all the geometric features of Ni(IV), but this is a local maximum, not a minimum.

The ligand class 2,2'-pyridylpyrrolide is surveyed, both for its structural features and its electronic structure, when attached to monovalent K, Cu, Ag, Au, and Rh. The influence of pyrrolide ring substituents is studied, as well as the question of push/pull interaction between the pyridyl and pyrrolide halves. The π donor ability of the pyrrolide is found to be less than that of an analogous phenyl. However, in contrast to the phenyl analog, the HOMO is pyrrolide π in character for pyridylpyrrolide complexes of copper and rhodium, while it is conventionally metal localized for planar, d(8) rhodium pyridylphenyl. Monovalent three-coordinate copper complexes show great deviations from Y-shaped toward T-shaped structures, including cases where the pyridyl ligand bonds only weakly.

Breaking of the carbon-hydrogen bond of benzene and pyridine is observed with (PNP)V(CH 2 tBu) 2 (1), and in the case of benzene, the formation of an intermediate benzyne complex (C) is proposed, and indirect proof of its intermediacy is provided by identification of (PNP)V]O(h 2 -C 6 H 4 ) in combination with DFT calculations.

The synthesis and characterization of a Cu(I) complex with a cis-bidentate monoanionic nitrogenous ligand, 2-pyridylpyrrolide, L, is reported. This shows binding of one base B = MeCN or CO per copper in a species LCu(B), but this readily releases the volatile ligand under vacuum with aggregation of transient LCu to a mixture of two enantiomers of a chiral trimer: a zwitterion containing inequivalent Cu(I) centers, possible via a new bonding mode of pyridylpyrrolide, and one with nitrogen lone pairs donating to two different metals. Density functional theory calculations show the energetics of both ligand binding and aggregation (including dimer and monomer alternatives), as well as the ability of this ligand to rotate away from planarity to accommodate a bridging structural role. The trimer serves as a synthon for the simple fragment LCu.