From Salicylaldehyde to Chiral Salen Sulfonates – Syntheses, Structures and Properties of New Transition Metal Complexes Derived from Sulfonato Salen Ligands

Coordination complexes derived from chiral and nonchiral sulfonato salen ligands {(SalenSO 3 )Na 2 : N,N'-bis(5-sulfonatosalicylidene)-1,2-diaminoethane disodium salt, [(R,R) and (S,S)-CySalenSO 3 ]NaK: (R,R) and (S,S)-N,N'-bis(5-sulfonato-salicylidene)-1,2-diaminocyclohexane sodium-potassium salt) have been synthesized. The crystal structures of the chiral and nonchiral Ni" complexes [Ni(SalenSO 3 )]Na 2 (1) and [Ni((R,R)CySalenSO 3 )]NaK (2) were solved. The other chiral and nonchiral sulfonato salen complexes, [Cu(SalenSO 3 )]Na 2 (4), [Cu((R,R)CySalenSO 3 )]NaK (5), [Cu((S,S)CySalen-SO 3 )]NaK (6) and [Zn(SalenSO 3 )]Na 2 (7) got hydrolyzed before suitable crystals could form. Yet, their hydrolysis led to the formation of single crystals of the residues of total or partial hydrolysis: 5-sulfonatosalicylaldehyde sodium salt (A), N-(5-sulfonatosalicylidene)-1,2-diaminoethane copper(II) [Cu-(SalSO 3 )] (8) and (R,R)-N-(5-sulfonatosalicylidene)-1,2-diaminocyclohexane copper(II) {Cu[(R,R)CySalSO 3 ]} (9). All compounds were studied with IR and UV/Vis spectroscopy; chiral compounds were also investigated by circular dichroism. The magnetic properties of the copper compounds were investigated. Whereas 8 shows intermolecular antiferromagnetic interactions between mononuclear Cu II complexes, 7 presents a weak intramolecular ferromagnetic coupling (J = 0.66 cm -1 , H = -JŜ Cu1 Ŝ Cu2 ), which has been rationalized by DFT calculations.