BINUCLEAR METAL(II) (M = CO, CU) COMPLEXES OF 3,5-BIS(N,N-BIS[2-(DIETHYLAMINO)ETHYL]AMINOMETHYL)PYRAZOLE

A new binucleating pyrazole ligand, 3,5-bis{N,N-bis[2-(diethylamino)ethyl]aminomethyl}pyrazole (HL), has been synthesized. It forms cobalt(II) and copper(II) complexes of the general formula [M2(L)(X)](BPh4)2.n(acetone) (M = Co, Cu; X = CH3COO-, N3-; n = 0-3), where two metal ions are bridged by the endogenous pyrazolate group and the exogenous X group. Electronic spectra of the cobalt(II) and copper(II) complexes suggest a trigonal-bipyramidal configuration around each metal ion. Magnetic properties have been examined over the temperature range 75-300 K. The cobalt(II) complexes [Co2(L)(CH3COO)](BPh4)2.acetone and [Co2(L)(N3)](BPh4)2.2acetone both show a slight increase of magnetic moment with lowering of temperature (from 4.03 and 3.94-mu-B, respectively, at 300 K to 4.16 and 4.08-mu-B, respectively, at 85 K). [Cu2(L)(CH3COO)](BPh4)2 shows a weak antiferromagnetic spin-coupling (J = -7.02 cm-1 based on spin Hamiltonian H = -2JS1.S2). [Cu(L)(N3)](BPh4)2.acetone exhibits a much lowered magnetic moment (1.10-mu-B at 300 K) owing to a strong antiferromagnetic spin coupling but its cryomagnetic property could not be simulated based on the Heisenberg model.