STRUCTURAL, SPECTRAL AND MAGNETIC INVESTIGATIONS OF VARIOUS TYPES OF COMPOUNDS AND THEIR ISOMERS ISOLATED FROM THE SYSTEM COPPER(II)-C(CN)3-PYRAZOLE

From the system Cu(II)-C(CN)3--Hpz (Hpz = pyrazole) the following compounds were isolated: [Cu{C(CN)3}(Hpz)4][C(CN)3] 1, [Cu{C(CN)3}2(Hpz)3] 2, alpha-[Cu{C(CN)3}2(Hpz)2] 3, beta-[Cu{C(CN)3}2(Hpz)2] 4 and [Cu{Hpz.C(CN)3}2] 5. They were studied by the use of spectroscopic and cryomagnetic methods. The structures of 1 and 2 were refined to R values of 0.0369 and 0.0374 for 1346 and 2066 independent reflections respectively. Compound 1 crystallises in space group P2(1)/c, with a = 9.568(4), b = 16.692(7), c = 14.957 (9) angstrom, beta = 94.05(4)-degrees and Z = 4; 2 crystallises in space group P1BAR, with a = 7.607(4), b = 8.942(6), c = 16.027(10) angstrom, alpha = 95.95(6), beta = 90.83(5), gamma = 106.88(5)-degrees and Z = 2. Both compounds show elongated pseudo-octahedral copper environments, with the Hpz molecules in the equatorial plane. In 1 one C(CN)3 group bridges the Cu(II) atoms in axial positions while the second group is anionic. Compound 2 contains mono- as well as bi-dentate bridging C(CN)3 groups; the latter join the basic structure units into binuclear species. Weak ferromagnetic coupling operates between the copper(II) centres inside the dimers. Physical measurements show that compounds 3 and 4 display rhombic octahedral arrangements around Cu(II) in which all C(CN)3 groups are bridging. The alpha and beta compounds are distortion isomers. Compound 5, a coligand isomer with respect to 3 and 4, contains new anionic chelate ligands, HN = C(pz)CH(CN)2-, formed by nucleophilic addition. In all these three compounds polymeric chains are present in which and between which there is magnetic interaction.