Hexamine copper(II) coordination polymers: synthesis, structure and magnetic properties

Four new one-dimensional (1D) polymeric complexes, {[Cu4(L1)2(µ-Br)2(µ4-CO3)]Br(ClO4)3·3H2O}n (1), {[Cu2L2(µ-Cl)Cl2] (ClO4)2·H2O}n (2), {[Cu2L3(µ-Cl)2](ClO4)2}n (3), and {[Cu2L4(µ-Cl)2](ClO4)2}n (4), have been synthesized and characterized, where L1 = N,N,N′,N′-tetrakis(3′-aminopropyl)-1,3-propylenediamine, L2 = N,N,N′,N′-tetrakis(2′-aminoethyl)-1,3-propylenediamine, L3 = N,N,N′,N′-tetrakis(2′-aminoethyl)-1,4-butylenediamine, L4 = N,N,N′,N′-tetrakis(2′-aminoethyl)-1, 6-hexylenediamine. X-Ray structure analysis revealed that the polymeric complexes, created by the bridging groups which are exhibited in the formula, present different 1D coordination motifs: double-stranded chains with voids of 43.5 A2 for 1, sigmoid chains for 2, zigzag chains for 3 and 4 with different coordination polyhedra. Various hydrogen bonding interactions such as N–H⋯Cl, N–H⋯O, C–H⋯Cl, N–H⋯Br and O–H⋯Br join the polymeric chains to generate two-dimensional networks with bigger voids. Magnetic susceptibility data were fitted according to the molecular structures using Hamiltonians: H = −2J1(S2S3 + S1S4) − 2J2(S2S1) − 2J3(S1S3 + S2S4) − 2J4(S3S4), which corresponds to a rectangular array of spins for 1, and H = −2JS1S2 corresponds to a dinuclear array of spins for 2, 3 and 4. It was found that the coupling constants of 1 are −60, −113, −54 and −11 cm−1, and those of 2, 3, and 4 are −2.46, −1.56 and −0.15 cm−1, respectively.