Synthesis and specific features of the structure of the mixed anionic six-coordinate silicon complexes with the (O,O)-dianionic and (C,O)-monoanionic chelate ligands

Dicyclohexylammonium salts of bis(1,2-catecholato-O,O')-[(N-methylacetamido)methyl-C,O]silicate and bis(1,2-catecholato-O,O')-[(2-oxohexahydroazepin-1-yl)methyl-C,O]silicate were synthesized by the transesterification of the corresponding trimethoxysilyl derivatives by pyrocatechol in the presence of dicyclohexylamine. According to the X-ray diffraction data, the synthesized salts are the anionic silicon complexes, in which the Si atoms are six-coordinate due to two (O,O')-dianionic and one (C,O)-monoanionic chelate ligands. In the latter, chelating occurs due to the formation of the intramolecular (intraionic) coordination bond O -> Si.