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

Four new one-dimensional (1D) polymeric complexes, {[Cu-4(L-1)(2)(mu-Br)(2)(mu(4)-CO3)]Br(ClO4)3 center dot 3H(2)O}(n) (1), {[Cu2L2(mu-Cl)Cl-2] (ClO4)(2)center dot H2O}(n) (2), {[Cu2L3(mu-Cl)(2)](ClO4)(2)}(n) (3), and {[Cu2L4(mu-Cl)(2)](ClO4)(2)}(n) (4), have been synthesized and characterized, where L-1 = N,N,N',N'-tetrakis(3'-aminopropyl)-1,3-propylenediamine, L-2 = N,N,N',N'-tetrakis(2'-aminoethyl)-1,3-propylenediamine, L-3 = N,N,N',N'-tetrakis( 2'-aminoethyl)-1,4-butylenediamine, L-4 = 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 angstrom(2) for 1, sigmoid chains for 2, zigzag chains for 3 and 4 with different coordination polyhedra. Various hydrogen bonding interactions such as N-H center dot center dot center dot Cl, N-H center dot center dot center dot O, C-H center dot center dot center dot Cl, N-H center dot center dot center dot Br and O-H center dot center dot center dot 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 = -2J(1)(S2S3 + S1S4) - 2J(2)(S2S1) - 2J(3)(S1S3 + S2S4) - 2J(4)(S3S4), which corresponds to a rectangular array of spins for 1, and H = -2JS(1)S(2) 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.