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‐sulfonatosalicylidene)‐1,2‐diaminocyclohexane sodium–potassium salt} have been synthesized. The crystal structures of the chiral and nonchiral Ni II 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 )CySalenSO 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 = – J Ŝ Cu1 Ŝ Cu2 ), which has been rationalized by DFT calculations.