cis-Tetracarbonylbis(tricyclohexylphosphine)molybdenum(0) and pentacarbonyl(tricyclohexylphosphine)molybdenum(0).

In the present redetermination of the complex cis-tetracarbonylbis(tricyclohexylphosphine)molybdenum(0), (I), [Mo(C(18)H(33)P)(2)(CO)(4)] or cis-eta(1)-[P(C(6)H(11))(3)](2)Mo(CO)(4), the Mo atom has a distorted octahedral geometry with a large P-Mo-P angle of 104.8 (1) degrees. A strong trans influence on the carbonyls in (I) is seen in a shortening of the Mo-C and a lengthening of the C-O distances opposite the phosphines compared with those that are cis.

Na2[(mu-N,N'-C10H12N2O8)(mu-O)(mu-S)-Mo2O2].2H2O.

Analogs of bridging-oxo complexes of dimolybdenum(V) where sulfide replaces one or both bridges are known. After reduction of [(MoO3)2(mu-edta)]4- (edta is ethylenediaminetetraacetate) with dithionite at pH 6 in the absence of dioxygen, slow replacement of bridging oxide with sulfide produced in situ produces the title compound, disodium mu-(ethylenediaminetetraacetato)-mu-oxo-mu-sulfido-bis[oxomolyb denum(V)] dihydrate, Na2-[Mo2O3S(C10H12N2O8)].2H2O.

Structural and enzymatic studies of a new analogue of coenzyme B12 with an alpha-adenosyl upper axial ligand.

A new analogue of coenzyme B12 (5'-deoxyadenosylcobalamin, AdoCbl), in which the configuration of the N-glycosidic bond in the Ado ligand is inverted [(alpha-ribo)AdoCbl], has been synthesized and its crystal structure determined by X-ray diffraction [MoKalpha, lambda = 0.71073 A, monoclinic P212121, a = 16.132(12) A, b = 21.

Cis Effects in the Cobalt Corrins. 1. Crystal Structures of 10-Chloroaquacobalamin Perchlorate, 10-Chlorocyanocobalamin, and 10-Chloromethylcobalamin.

The crystal structures of 10-chloroaquacobalamin perchlorate hydrate (10-Cl-H(2)OCbl.ClO(4)) (Mo Kalpha, 0.710 73 Å, monoclinic system, P2(1), a = 11.