Ligand-to-metal ratio controlled assembly of cobalt complexes containing ortho-carborane thiolato and butyl thiolato ligands.

Treatment of ortho-carborane, n-butyl lithium, sulfur, and CpCo(CO)I(2) with differing ratios led to four new compounds [(CpCoS(2)C(2)B(10)H(10))(CpCoSC(2)B(10)H(11))(SC(4)H(9))] (3), [(CpCo)(2)S(2)(S(2)C(2)B(10)H(10)) (SC(2)B(10)H(10))(SC(4)H(9))] (4), [(CpCo)(2)Co(SC(4)H(9))(6)](+)[Co(S(2)C(2)B(10)H(10))(2)](-) (5), and [(CpCo)(2)Co(SC(2)B(10)H(11))(SC(4)H(9))(5)](+)[Co(S(2)C(2)B(10)H(10))(2)](-) (6). Compound 3 contains a rhombic Co(2)(mu(2)-S)(2) core and can be considered as an adduct of the two 16e half-sandwich monomers CpCo(S(2)C(2)B(10)H(10)) (1) and CpCo(SC(4)H(9))(SC(2)B(10)H(11)). Compound 4 is a trinuclear complex containing a cuboidal [Co(3)(mu(3)-S)(2)(mu-S)(2)] core, and one cobalt atom is coordinated by six sulfur atoms in a distorted octahedral geometry. Compound 5 consists of a linear-type trinuclear cobalt(III) monocation bridged by six n-butyl thiolato units and a square-planar cobalt(III) monoanion [Co(S(2)C(2)B(10)H(10))(2)](-). However, in 6, one ortho-carborane monothiolato ligand [SC(2)B(10)H(11)](-) has replaced one n-butyl thiolato ligand in 5. This leads to a nonlinear arrangement of the three cobalt atoms in the cation and the nonplanar [Co(S(2)C(2)B(10)H(10))(2)](-) anion in 6. Interestingly, the treatment of the 16e half-sandwich CpCo(S(2)C(2)B(10)H(10)) (1) by [N(n-Bu)(4)]Br afforded the ionic compound 7, [N(n-Bu)(4)](+)[Co(S(2)C(2)B(10)H(10))(2)](-), containing a square-planar anion.

1H NMR study of the inclusion of Costa-type organocobalt(III) complexes in cyclodextrins.

The inclusion behavior between Costa-type complexes and cyclodextrins (CDs) was studied by 1H NMR in aqueous solution. The results indicated that 1:1 inclusion complex was formed, in which the alkyl group of the guest was included in the cavity of CDs. The stability constants of the inclusion complexes were determined by the quantitative 1H NMR method. The effects on stability constants were discussed when various host and guest compounds were used.

Reactivity of the 16e (p-cymene)Ru half-sandwich complex containing a chelating 1,2-dicarba-closo-dodecaborane-1,2-dithiolate ligand towards diynes.

The reactions of the 16e half-sandwich complex (p-cymene)Ru(S(2)C(2)B(10)H(10)) (Ru16e) with 1,4-diethynylbenzene (L1), 3',6-diethynyl-1,1'-binaphthyl-2,7'-diyl diacetate (L2), 2-bromo-5-ethynylthiophene (L3) and 2,5-diethynylthiophene (L4) lead to 18e mononuclear complexes (p-cymene)Ru(S(2)C(2)B(10)H(9))(H(2)CCPhC≡CH) (1), (p-cymene)Ru(S(2)C(2)B(10)H(9))[H(2)CC(C(24)H(16)O(4))C≡CH] (2), (p-cymene)Ru(S(2)C(2)B(10)H(9)) [H(2)CC(C(4)H(2)S)Br] (3) and (p-cymene)Ru(S(2)C(2)B(10)H(9)) [H(2)CC(C(4)H(2)S)C≡CH] (4), respectively. In all of them, metal-induced B-H activation has occurred, which leads to a stable Ru-B bond, and the structures take a cisoid arrangement. Only in the case of L4, the binuclear complexes [(p-cymene)Ru(S(2)C(2)B(10)H(9))](2)[H(2)CC(C(4)H(2)S)CCH(2)] (5a and 5b) are observed, which are conformational isomers generated by the differing orientations of the p-cymene unit. 4 can be readily converted to the complex (p-cymene)Ru(S(2)C(2)B(10)H(9))[H(2)CC(C(4)H(2)S)COCH(3)] (6) in the presence of silica and H(2)O. All of these products 1-6 were characterized by NMR, IR, elemental analysis and mass spectrometry. The structures of 1, 3, and 5a were also determined by single-crystal X-ray diffraction analysis.

Synthesis, spectroscopic characterization, axial base coordination equilibrium and photolytic kinetics studies of a new coenzyme B12 analogue-3'-deoxy-2',3'-anhydrothymidylcobalamin.

A new coenzyme B12 (AdoCbl) analogue, 3'-deoxy-2',3'-didehydrothymidylcobalamin (2',3'-anThyCbl) was prepared by the reaction of 5'-iodo-3'-deoxy-2',3'-dihydrothmidine with reduced B12a, and characterized by UV-Vis, CD, ESI-MS and NMR spectroscopies. Its axial base (dbzm) coordination equilibria with pH's and temperatures were investigated and showed similar features to those of coenzyme B12. Photolytic dynamics studies under homolytic and heterolytic conditions demonstrated that the Co-C bond of the analogue is slightly more photolabile relative to coenzyme B12.