Bis(µ-di-phenyl-phosphan-yl)bis-[(tri-methyl-phosphane)cobalt(I)](Co-Co).

The title compound, [Co2{P(C6H5)2}2(C3H9P)4], was obtained by the addition of di-phenyl-phosphane to a solution of Co(CH3)(C3H9P)4. The dinuclear complex mol-ecule exhibits inversion symmetry with the inversion centre located between the two Co(I) atoms. The short Co-Co distance of 2.3670 (8) Šlies within the range of metal-metal double bonds. As a result of inversion symmetry, the four-membered Co2P2 core is rigorously planar, and the two bridging P(C6H5)2-ligands and the terminal C3H9P ligands are arranged in a pseudo-tetra-hedral fashion about the Co(I) atom.

Cobalt induced tandem C-H activation/decarbonylation of various aromatic aldehydes and related benzylic alcohols forming mononuclear aryl monocarbonyl complexes.

Reactions between Co(CH(3))(PMe(3))(4) and various ortho-substituted aromatic aldehydes (Ar(R(1),R(2))CHO) and related benzylic alcohols (Ar(R(1),R(2))CH(2)OH) proceed with high selectivity to give the mono carbonyl complexes Aryl(R(1),R(2))(PMe(3))(3)Co(CO): R(1) = H, R(2) = CH(3) (1), R(1)= H, R(2) = ethyl (2), R(1) = CH(3), R(2) = CH(3) (3), R(1) = H, R(2) = NH(2) (4), R(1) = F, R(2) = F (5), R(1) = H, R(2) = CF(3) (6), and R(1) = H, R(2) = benzo (7). This tandem C-H bond activation/decarbonylation reaction provides easy and rapid access under mild conditions (-70 degrees C) to the first isolated trimethylphosphine stabilized aryl-monocarbonyl complexes of cobalt. X-ray diffraction studies were performed on ortho-amino substituted complex 4, ortho-trifluormethyl 6, and naphthyl derivative 7.

Meridional bicyclometalation with iron: a novel way of forming dianionic [C,N,C]-ligands.

Bicyclometalation of aromatic substrates containing imine anchoring groups is achieved with a dimethyliron complex at -70 degrees C; azadiene systems undergo a regiospecific activation of 1,4-CH/N interchanged C-H bonds which may be aromatic or vinylic.

Synthesis, Structure, and Magnetic Properties of Low-Valent Triangulo Cobalt-Hydride Clusters [XCo(3)(&mgr;-CO)(3)(PMe(3))(6)].

Syntheses and properties of low-valent clusters [X{Co(&mgr;-CO)(PMe(3))(2)}(3)], X = none (1), H (2), and H(3) (3), are reported. All solids are isostructural as explicitly shown by single-crystal structure data. The molecular structures of C(21)H(54)Co(3)O(3)P(6) (1) and C(21)H(57)Co(3)O(3)P(6) (3) contain central Co(3) units which form perfect equilateral triangles with Co-Co distances of 2.4055(5) and 2.432(1) Å, respectively. Both compounds crystallize in trigonal space group R&thremacr;c, with Z = 6: 1, a = 10.678(1) Å, c = 52.298(11) Å; 3, a = 10.679(2) Å, c = 52.729(12) Å. Compounds 1 and 2 form a continuous range of solid solutions. Powder samples exhibit molecular paramagnetism of different extent: At 298 K the effective magnetic moments for 1-3 are &mgr;(eff)/&mgr;(B) = 1.9, 3.1, and 2.7, respectively. The magnetic behavior could be rationalized in terms of the Curie-Weiss law for a one electron system (1) and two electron system (2). The two electron approximation has been discussed as well for 3 above 6.2 K. A description of the scope of exchange coupling is presented for 1.

Dichlorodinickel(I) Complexes with µ2 -CO or µ2 -CS Bridges and Trimethylphosphane Ligands: Homologous Composition, but Different Frameworks.

High ligand mobility is shown by the coordinatively unsaturated nickel(I) compound 1 with a short Ni-Ni distance and an asymmetric CO bridge. The thio homologue 2 contains the novel (thiocarbonyl)trimethylphosphorane bridging ligand, which sits like a "stork's nest" on top of the roof-shaped dinuclear complex. In contrast to 1, complex 2 does not show fluctional behavior and can be methylated without decomposition. X=Cl, Me.

Four- and five-membered cobaltacycles by regioselective cyclometallation of benzyl sulfide derivatives via Co(v) intermediates.

C-H activation through the coordination of a benzyl sulfide anchoring group with a C-S bond cleavage at a Co(v) center constitutes a regiospecific access to four- and five-membered metallacycles under mild conditions.

First regioselective cyclometalation reactions of cobalt in arylketones: C-H versus C-F activation.

Phenyl ketones react smoothly under mild conditions with low valent cobalt(i) adducts to form new and stable five-membered cobaltacycles via C-H and C-F activation.