Cyclic seven-membered bisphosphanes, namely 1-aza-3,6diphosphacycloheptanes 3-5 (3: 3,6-diphenyl-1-(1-phenylethyl)-1-aza-3,6-diphosphacycloheptane; 4: 1-[(1R)-1-(4Јmethoxyphenyl)ethyl]-3,6-diphenyl-1-aza-3,6-diphosphacycloheptane; 5: 3,6-diphenyl-1-[(1R)-1-phenylpropyl]-1-aza-3,6-diphosphacycloheptane), with chiral exocyclic substituents at the nitrogen positions have been synthesized, with the prevailing formation of meso stereoisomers (P R P S ) as kinetically controlled products, by stereoselective condensation of 1,2-bis(phenylphosphanyl)ethane, formaldehyde and primary optically pure amines, namely (S)-(-)-1-phenylethylamine, (R)-(+)-1-phenylethylamine, (R)-(+)-1-phenylpropylamine, (R)-(+)-1-(4Ј-methoxyphenyl)ethylamine. The meso stereoisomers of bisphosphanes 3 RSS , 3-5 RSR readily form neutral and cationic P,P-chelate complexes 6-9 with platinum(II) (6: