A hexacoordinated aluminium complex with a new type of seven-membered chelate ring involving a cyclic phosphate ester

Abstract

The molecular structure of the title compound, tris[2,3,4,5-tetrachloro-6- (4,8-di-tert-butyl-2,10-dimethyl-6-oxo-12H-5,7-dioxa-6λ. 5-phosphadibenzo[a,d]cycloocten-6-yloxy)phenoxido]aluminium benzene 0.25-solvate, [Al(C 29H 30C 14O 5P) 3]·-0.25C 6H 6, has been determined. The Al atom, with site symmetry 3, is hexacoordinate and is part of a new type of seven-membered chelate ring, with a catecholate O atom forming a covalent bond and a phosphoryl O atom forming a coordinate covalent bond. As expected, the Al - O coordinate bond is longer than the Al - O covalent bond. The phosphocine ring has a tub conformation, with an intramolecular C - H⋯O interaction between one of the ArCH 2 H atoms and the phosphoryl O atom. © 2004 International Union of Crystallography Printed in Great Britain - all rights reserved.