Metal-metal bonding in sterically frustrated dipalladium species.

Stoichiometric-deficient lithiation of (2,6-diisopropylphenyl)(4-methylpyridin-2-yl)amine and reaction with [(cod)PdCl2] (cod = 1,5-cyclooctadiene) yield a dimeric Pd complex. X-ray structural analysis of this complex reveals a very short Pd-Pd distance (2.429 A). Topological analysis of the electron density and the electron localization function from scalar relativistic density functional theory calculations clearly indicate a Pd(I)-Pd(I) sigma-bonding interaction, for which the corresponding occupied localized orbital can be identified.

Group 10 metal aminopyridinato complexes: synthesis, structure, and application as aryl-Cl activation and hydrosilane polymerization catalysts.

(4-Methyl-pyridin-2-yl)(trimethylsilanyl)amine (ApSi-H) and tert-butyl(4-methyl-pyridin-2-yl)amine (AptBu-H) were synthesized via salt metathesis and aryl amination reactions, respectively. Lithiation of these two aminopyridines using n-BuLi and the reactions with [(dme)NiCl2] (dme = dimethoxyethane) or [(cod)PdCl2] (cod = cyclooctadiene) in THF at low temperature gave rise--after workup in hexane--to group 10 amido compounds, [(ApSi)4Ni2], [(AptBu)2Pd], [(AptBu-H)(AptBu)2Ni], [(AptBu)3(C2H5O)3Ni3OLi(thf)], and [(AptBu)2Ni(tBupy)2] (tBupy = 4-tert-butylpyridine). The aminopyridinato complexes were characterized by X-ray crystal structure analysis. The highly strained binding situation of the aminopyridinato ligands suggested that these compounds might be efficiently converted into catalytically active species. The applications of some of the synthesized complexes as Suzuki cross-coupling catalysts (activation of aryl chlorides) are described and [(ApSi)4Ni2] is a rare example of a "phosphine-free" catalyst system. A number of late transition metal complexes were found to successfully catalyze polymerization of MeH2SiSiH2Me toward soluble, linear poly(methylsilane). Remarkable activity was observed for [(ApSi)2Pd].