Synthesis, Molecular Structure and Coordination Chemistry of the First 1‐Aza‐3,7‐diphosphacyclooctanes

The first representatives of a novel type of cyclic bis‐phosphines, namely, 1‐aza‐3,7‐diphosphacyclooctanes ( 4 , 5 ), were synthesized by condensation of 1,3‐bis(arylphosphino)propanes ( 2 , 3 ; aryl = phenyl or mesityl), formaldehyde and 5‐aminoisophthalic acid. Only the meso isomers were obtained, in good to satisfactory yield. The cyclic bis‐phosphines readily form P,P chelate complexes ( 6 , 7 ) with [PtCl 2 (cod)] (cod = 1,5‐cyclooctadiene). The bisphosphine 4 and the corresponding complex 6 are soluble in water in the presence of two equivalents of alkali metal hydroxide. The molecular structures of 1‐( meta ‐dicarboxyphenyl)‐3,7‐dimesityl‐1‐aza‐3,7‐diphosphacyclooctanes ( 5 ) and cis ‐{P,P‐1‐( meta ‐dicarboxyphenyl)‐3,7‐diphenyl‐1‐aza‐3,7‐diphosphacyclooctane}dichloroplatinum(II) ( 6 ) are reported.