STERIC CIS INFLUENCE AND LATERAL COMPRESSION OF THE METALLABICYCLE INBIS(DIOXIME) VITAMIN-B-12 MODELS

A. comparative study of the structural parameters of bis(dioxime) vita min B-12 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 crys tal structure of an organocobaloxime with cyclohexanedionedioxime(chgH ) as the equatorial ligand is also reported. The compound MeCo(chgH)(2 )Py crystallises in the monoclinic system, with the space group P2(1)/ n with Z = 4 and unit cell parameters a = 8.7074(9), b = 9.3989(8), c = 23.886(2) Angstrom and beta = 91.862(8)degrees. (C) 1998 Elsevier Sc ience S.A. All rights reserved.