Auxiliary Part of Ligand Mediated Unique Coordination Chemistry of Copper (II)

Abstract Six N,N,O‐donor Schiff‐base ligands, HL1‐HL6, [HL1/HL2/HL3={2‐(2‐piperazin‐1‐yl)ethylimino)methyl)‐4‐(Cl/H/Me)‐phenol}; HL4/HL5/HL6={2‐(2‐morpholine/piperidine/ pyrrolidine −1‐yl)ethylimino)methyl)‐4‐chlorophenol}, have been designed by combining 5‐R‐2‐hydroxy‐benzaldehyde, (R=Cl/H/Me) and N‐(2‐aminoethyl)‐Y, (Y=piperazin/morpholine/ piperidine/pyrrolidine) with the view to explore the role of R and X (part of Y excluding coordinating N) on the coordination chemistry of Cu(II) in presence of bromide as counter anion. HL1‐HL6 formed in situ on reaction with Cu(II)Br 2 produce complexes 1–6 , respectively. Complex 1, [ Cu(II) 2 Cu(I) 2 (L1)(MeOH) 2 Br 7.30 ], is a mixed valence Cu(I)‐Cu(II) species having phenyl ring brominated at ortho position with 0.65 occupancy. Complexes 2–4 are mononuclear species with general formula [Cu{L2/L3/L4)}Br 2 ]. Complexes [Cu 3 (L5)Br 4 ] ( 5) and [Cu 3 (L6)Br 4 ] ( 6) are trinuclear species having similar structure but exhibit different magnetic property, 5 is ferro‐ ( J = +16.64 cm −1 ) and 6 is antiferromegnetic ( J =–11.76 cm −1 ). The influence of R and X on bromonation, magnetic property and nuclearity issues have been rationalized by DFT calculations.