COMPLEMENTARITY AND INTERNAL CONSISTENCY BETWEEN MAGNETIC AND OPTICAL-PROPERTIES FOR THE MNIICUII HETERODINUCLEAR COMPOUND [MN(ME6-[14]ANE-N4)CU(OXPN)](CF3SO3)2 (ME6-[14]ANE-N4 = (+/-)-5,7,7,12,14,14-HEXAMETHYL-1,4,8,11-TETRAAZACYCLOTETRADECANE - OXPN = N,N'-BIS(3-AMINOPROPYL)OXAMIDE)

A heterodinuclear compound of formula [Mn(Me6-[14]ane-N4)Cu(oxpn)](CF3SO3)2 (hereafter abbreviated as MnCu), with Me6-[14]ane-N4 standing for (+/-)-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane and oxpn for N,N'-bis(3-aminopropyl)oxamide, has been synthesized. Its crystal structure has been solved. It crystallizes in the monoclinic system, space group P2(1)/a. The lattice parameters are a = 17.781(7) angstrom, b = 18.202(5) angstrom, c = 12.893(4) angstrom, and beta = 105.48(3)-degrees with Z = 4. Its structure consists of oxamido-bridged Mn(II)Cu(II) dications and noncoordinated triflate anions. The Mn(II) ion is in distorted octahedral surroundings, and the Cu(II) ion in square-planar surroundings. The intramolecular Mn --- Cu separation is equal to 5.436 angstrom. The temperature dependence of the magnetic susceptibility has been investigated in the 300-2 K range and has revealed a ground quintet-excited septet energy gap of 3J = -93.9 cm-1. It has also indicated that the zero-field splitting within the quintet state was too small to be detected from the magnetic data. Both NMR and EPR properties have been investigated. The NMR spectrum in CD3CN solution is poorly resolved. The X-band powder EPR study has allowed the estimation of values of the axial and rhombic zero-field splitting parameters within the S = 2 state. The absorption properties of MnCu have also been investigated. The main feature of the spectrum is a sharp and intense band corresponding to the 6A1 --> 4A1 + 4E spin-forbidden transition for Mn(II) activated by an exchange mechanism. The temperature dependence of the intensity of this band has offered an alternative method to determine the quintet-septet energy gap.