Organoantimony(V) cyanoximates: synthesis, spectra and crystal structures

A series of 25 new organoantimony(V) cyanoximates has been synthesized and studied using IR, visible, and NMR spectroscopy and X-ray analysis. Crystal structures were determined for compounds (C6H5)4Sb[ONC(CN)C(O)NH2] (1) and (C6H5)4Sb[ONC(CN)C(O)N(CH3)2] (2). Both complexes crystallized in the monoclinic space group P2(1)/c (Z = 4) with unit cell parameters (A, grad) of a = 14.921(3), b = 10.165(2), c = 17.571(7), beta = 113.26(6) for compound 1, and a = 16.415(4), b = 10.406(3), c = 17.152(3), beta = 17.152(3), beta = 117.79(2) for compound 2. For 5438 and 5056 independent reflections the refinement yielded R-factors 0.022 and 0.037 for the structures of 1 and 2, respectively. Cyanoxime anions are bound to the antimony(V) atoms in a monodentate fashion via the oxygen atoms of the oxime groups. The ligands adopt trans-anti configuration in these compounds. The coordination polyhedron in both complexes is a distorted trigonal bipyramid with the axial location of the cyanoxime ligand. A similar binding mode of other anions in synthesized organoantimony(V) complexes has been offered on the basis of the similarity of their IR spectra to those of the compounds whose structures were determined crystallographically. The exact assignment of vibrations involving the oxime group was carried out using synthesized 15N(53%), isotopomers.