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A simple and general route to the synthesis of cobaloxime with mixed dioxime ligands, XCo(L)(L′)Py, L,L′=dmgH/dpgH and chgH/dpgH; X=Cl, Br, NO2, N3, has been described. These compounds are reported for the first time. The synthesis is confirmed by the X-ray structures of N3Co(dmgH)(dpgH)Py and N3Co(chgH)(dpgH)Py. The cis and trans effects on these complexes and on XCo(L)2Py (L=dmgH, chgH, dpgH; X=Cl, Br, NO2, N3) complexes have been studied by 1H-, 13C-NMR, UV, and X-ray. For a range of X ligands, a clear trend between the 1H, 13C chemical shifts of the equatorial and axial ligands as well as with the Co–dioxime CT band has been observed. The analysis of the 13C values and X-ray data shows that one dioxime wing effects the other dioxime wing in the mixed dioxime complexes.

A simple and general route to the synthesis of organocobaloxime with mixed dioxime ligands, RCo(dmgH)(dpgH)Py and RCo(chgH)(dpgH)Py, has been described. The 13C-NMR chemical shifts have been analysed to see whether one dioxime wing has any effect on the other dioxime wing. The first crystal structure of an organocobaloxime with mixed dioxime ligand in the same complex, BnCo(dmgH)(dpgH)Py and BnCo(chgH)(dpgH)Py, is reported.

A synthetic scheme leading to the (X)(Y)bis(1,2-cyclohexanedionedioximato)cobalt(III) complexes, where X=Cl, N 3 , ClCH 2 , CH 3 , C 2 H 5 and Y=PPh 3 and Py is reported. The complexes have been characterized by the usual spectroscopic techniques and have been compared with the reported analogous compounds having other dioximes as the equatorial ligands. The first crystal structure of an inorganic cobaloxime with 1,2-cyclohexanedionedioxime (Nioxime) is reported. For a range of X ligands, a clear trend between 31 P, 13 C, 1 H chemical shifts of the equatorial and axial ligands as well as with the Co→chgH charge transfer band has been observed.

A comparative study of the structural parameters of bis(dioxime) vitamin B12 models reveal an interesting squeezing of the metallabicycle. The lateral compression and the butterfly bending angle have a common origin in the steric bulk of the dioxime substituents. The first crystal structure of an organocobaloxime with cyclohexanedionedioxime(chgH) as the equatorial ligand is also reported. The compound MeCo(chgH)2Py crystallises in the monoclinic system, with the space group P21/n with Z=4 and unit cell parameters a=8.7074(9), b=9.3989(8), c=23.886(2) A and β=91.862(8)°.

An expedient synthesis of previously unknown (1 Z , 3 Z )-1, 4-dibromobutadiene is reported. When this dibromide is treated with s- or t-butyllithium, (1 Z , 3 Z )-1-bromo-4-lithio-butadiene is generated. Treatment of the dibromide with four equivalents of t-butyllithium gives (1 Z , 3 Z )-dilithiobutadiene. Reaction of (1 Z , 3 Z )-1-bromo-4-lithiobutadiene with (η 5 -C 5 H 5 )Fe(CO) 2 I gives (1 Z , 3 Z )-(η 5 -C 5 H 5 )Fe-(CO) 2 CH=CHCH=CHBr. X-ray crystallographic analysis of this latter compound establishes the geometry about the bromobutadiene ligand.