Coordination compounds with a trans-stereochemistry were prepared for ligands (4-ClC 6H 4)CH NCH 2(4′-ClC 6H 4) ( L a), (2,4,6-Me 3C 6H 2)CH NCH 2(4′-ClC 6H 4) ( L b) and (2,6-Cl 2C 6H 3)CH NCH 2(4′-ClC 6H 4) ( L c) and were shown to be precursors of the corresponding cyclometallated compounds. The reactions between cis-[PtCl 2(dmso) 2] and ligands ArCH NCH 2(4′-ClC 6H 4) (Ar = 2-BrC 6H 4 ( L d); 2-ClC 6H 4 ( L e); C 6F 5 ( L f); 2,6-F 2C 6H 3 ( L g)) under previously described conditions for cycloplatination of N-benzylidenebenzylamines gave a cyclometallated compound only for imine L f; the other imines produced coordination compounds with a cis arrangement from which cyclometallation could not be achieved. Formation of either cis or trans coordination compounds [PtCl 2( L)dmso] ( L = N-benzylidenebenzylamine) can be related to steric effects and to the E/ Z configuration of the C N bond. All compounds were fully characterized including structure determinations for trans-[PtCl 2{(4-ClC 6H 4)CH NCH 2(4′-ClC 6H 4)}SOMe 2] ( 2a), trans-[PtCl 2{(2,6-Cl 2C 6H 3)CH NCH 2(4′-ClC 6H 4)}SOMe 2] ( 2c) and the amine derivative trans-[PtCl 2(4-ClC 6H 4CH 2NH 2)SOMe 2] ( 2) obtained as a by-product.