Bis[2,3-Butanedione Di-oximato(1)]-Cobalt Complexes
Bulkowski, J. Cutler, A., David Dolphin, and Silverman, R.B.
Inorganic Synthesis," D.H. Busch, Ed., John Wiley & Sons, New York, Vol. XX
It has been found that pure products are obtained when a preformed cobaloxime is alkylated rather than obtaining the cobaloxime by a direct syn- thesis. Bromobis[2,3-butanedione dioximato(l-)] (dimethyl sulfide)cobalt(III), prepared here by a modification of the procedure of Hill and Morallee, serves as a very useful starting material, since both axial ligands are readily exchanged and the material can be prepared in good yield and purity. The majority of cobaloximes reported in the literature have pyridine as a sixth axial ligand, but we have found that the commercially available 4-m-butylpyridine (4-tert- bupy) is superior, since it decreases the solubility of the cobaloxime in water (which makes isolation of products easier) and increases the solubility of cobal- oxime in organic solvents. In addition, the tert-butyl group serves as a useful nmr marker. The following procedures were reported:- A. BROMOBIS[2,3-BUTANEDIONE DIOXIMATO(l-)] (DIMETHYL SULFIDE)COBALT(III) B. BROMOBIS(2,3-BUTANEDIONE DIOXIMATO(l-)]- (4-tert-BUTYLPYRIDINE)COBALT(III) C. BIS[2,3-BUTANEDIONE DIOXIMATO(l-)] (4-tert-BUTYLPYRIDINE)-(2-ETHOXYETHYL) COBALT (III) D. BIS[2,3-BUTANEDIONE DIOXIMATO(l -)] (4-tert-BUTYLPYRIDINE)-(ETHOXYMETHYL)COBALT(III)