Filinchuk Y. Synthesis and stereochemistry of copper(I) pi-complexes with allylic derivatives of azomethynes and thiosemicarbazide

By means of the alternating-current electrochemical synthesis crystals of 22 new copper(I) complexes with allylacetone oxime and azyne, allylic derivatives of aldimines, guanidinium, isothiouronium, aldiminium salts and 4-allylthiosemicarbazide have been obtained. X-ray structure determination and crystallochemical analysis have been performed. The character of pyramidal distortion of the central atom environment suggests a rigidity of coordination polyhedra, the copper atom rather adapts to the environment than fulfills its own stereochemical requirements. The donor properties of nitrogen atoms decrease in series >C=N-R, >C=N-OH, >C=N-N=C<. A directedness and conformational rigidity of functional groups in azomethynes and thiosemicarbazide derivatives advantageously distinguish them from nitrile or amine ligands, which first of all meet the requirements of the metal center. It was shown that the distinctive feature of the protonated azomethyne ligands is a conformational rigidity of nitrogen-containing groups forming a system of strong hydrogen bonds. The latter influence both a structure of inorganic fragment and the pi-bonding effectiveness. A number of revealed stereochemical peculiarities of azomethyne, thioamide and nitrato-group coordination is defined by electron pairs directedness near the N, S and O atoms, respectively. The formation of 6-membered pi,n- and 5-membered N,S-chelates with orthogonal N-Cu-S fragment in it by allylthiosemicarbazide molecule and copper atom gives rise to an unexpectedly efficient for copper(I) complexes with thioamide co-ligands Cu-(C=C) interaction. The revealed features offer possibilities for development of novel functional ligands with predetermined coordination properties.