1,3,6‐Azadiphosphacycloheptanes: A novel type of heterocyclic diphosphines

Abstract

Abstract The novel type of seven‐membered cyclic diphosphines, namely 1,3,6‐azadiphosphacycloheptanes, has been synthesized by condensation of 1,2‐bis(phenylphosphino)ethane, formaldehyde, and primary amines (aniline, p ‐toluidine, benzylamine, and 5‐aminoisophthalic acid) as a mixture of rac‐ and meso‐stereoisomers. The structures of rac‐stereoisomers of N ‐tolyl and N ‐(3′,5′‐dicarboxyphenyl)‐substituted diphosphines were investigated by X‐ray crystal structure analyses. The stereoisomers of N ‐(3′,5′‐dicarboxyphenyl)‐substituted compound were separated at a preparative scale, and their platinum(II) dichloride complexes were obtained. The corresponding meso‐isomer readily forms P , P ‐chelate complex with [PtCl 2 (cod)], whereas the rac‐stereoisomer forms oligomeric complex. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:125–132, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20397