Coordination d'anions organophosphores: 2eme partie. Perturbations provoquées par les coordinats “halogéno” et “pseudohalogeno” dans des complexes du zinc(II). Étude par spectro

Abstract

Infrared and nuclear magnetic resonance spectroscopy data are presented for a series of complexes [ZnXL], where L − denotes the {(C 2H 5O) 2POCHCOCH 2NR 2} − anion with R = CH 3 (La −) or C 2H 5 (Lb −) and X a halogen or pseudohalogen. The infrared data reveal that the splitting of the absorption v(P → O) depends on the nature of X − and is interpreted in terms of a crystal effect. The following order Cl − < NCO − ~ Br − < I − < NCS − < NCSe − is consistent with the ligand size. Nonequivalent protons on a given methylene group and nonequivalent methyl or ethyl groups bonded to nitrogen are detected by NMR spectroscopy of deuterochloroform solutions of these complexes. With La −, the rate of exchange increases in the order NCO −, Cl −, Br −, X − (X − = I −, NCS −, NCSe −). The kinetic parameters for exchange of nonequivalent N(CH 3) 2 groups were determined.