A Two-Dimensional Oxamate- and Oxalate-Bridged CuIImnII motif: Crystal Structure and Magnetic Properties of (Bu4N)2[Mn2{Cu(opba)}2ox]

A new compound of formula (Bu4N)(2)[M(n)2{Cu(opba)}(2)ox] (1) [Bu4N+ = tetra-n-butylammonium cation, H4opba = 1,2-phenylenebis(oxamic acid), and H(2)ox = oxalic acid] has been synthesized and magnetostructurally investigated. The reaction of manganese(II) acetate, [Cu(opba)](2-), and ox(2-) in dimethyl sulfoxide yielded single crystals of 1. The structure of 1 consists of heterobimetallic oxamato-bridged (CuMnII)-Mn-II chains which are connected through bis-bidentate oxalate coordinated to the manganese(II) ions to afford anionic heterobimetallic layers of 6(3)-hcb net topology. The layers are interleaved by n-Bu4N+ counterions. Each copper(II) ion in 1 is four-coordinate in a square planar environment defined by two amidate-nitrogen and two carboxylate-oxygen atoms from the two oxamate groups of the obpa ligand. The manganese(II) ion is six-coordinate in a somewhat distorted octahedral surrounding that is built by two oxalate-oxygen and four carbonyl-oxygen atoms from two [Cu(opba)](2-) units. The magnetic properties of 1 in the temperature range 1.9-300 K correspond to those expected for the coexistence of intralayer antiferromagnetic interactions of the type copper(1I) manganese(11) across oxamato and manganese(II)-manganese(II) through oxalato bridges plus a weak spin canting in the very low temperature domain. Simulation of the magnetic data through quantum Monte Carlo methodology reveals the magnitude of the intralayer magnetic interactions [J(CuMn) = 32.5(3) cm(-1), and J(CuMn) = 2.7(3) cm(-1)], their values being within the range of those previously observed in lower nuclearity systems.