NEW MIXED-LIGAND COPPER(II) COMPLEX AS A MODEL FOR THE METAL-BINDING ROLE OF 2-AMINOMETHYLBENZIMIDAZOLE, A CHELATING ANCHOR GROUP USED IN ION-EXCHANGER POLYMERS - SYNTHESIS, MOLECULAR AND CRYSTAL-STRUCTURE ANDPROPERTIES OF INOMETHYLBENZIMIDAZOLE)(IMINODIACETATO)COPPER(II), [CU(IDA)(2AMBZIMH)]

inomethylbenzimidazole)(iminodiacetato)copper(II), [Cu(IDA)(2AMBzImH)] = I, has been prepared and studied by spectral, magnetic, thermal and X-ray diffraction methods. In the crystal, all N-H ligand groups in I are involved in hydrogen bonding formation with O IDA atoms of three neighbouring molecules. This new mixed-ligand copper(II) complex cryst allizes in the monoclinic system, space group P2(1)/n (a = 7.900(1), b = 18.679(6), c = 9.229(1), beta = 110.82(1)degrees, Z = 4, R = 0.047, R-w = 0.137). One carboxylate O and the N atoms of ZDA and both N ato ms of 2AMBzImH define a distorted square. The flattened-square base py ramidal coordination (type 4+1) of the Cu(II) atom is accomplished by a longest apical Cu-(IDA) bond. The Cu(II) chelation by 2AMBzImH in I implies the coordination of the N-heterocyclic donor in trans to the C u-N(IDA) bond. That imposes a fac-chelating role to IDA beforehand rep orted for mixed-ligand Cu(II) complexes having a 1:1:2 Cu:IDA:N-hetero cyclic donor ratio, in clear contrast with the typical mer-chelating I DA role of complexes with a 1 : 1 : 1 Cu:IDA: N-heterocyclic donor rat io. The structure of [Cu(IDA)(2AMBzLmH)] agree well with the results a nd proposals of a recent study [9] on synthetic ion exchangers having o-aminoalkylbenzimidazole anchor groups, in which is proved that the e xchanger with 2AMBzImH N-anchored groups display fast-uptake and regen eration kinetics and good selectivity for Cu2+ ions. (C) 1998 Elsevier Science B.V. All rights reserved.