OUTER AND INNER COORDINATION SPHERE CHEMISTRY OF POLYAZACYCLOPHANE PLATINUM(II) COMPLEXES - CRYSTAL-STRUCTURE OF [PTBR4](2)(H(4)L1)CENTER-DOT-H2O (L1 = 2,6,9,13-TETRAAZA[14]PARACYCLOPHANE)

The interaction of PtCl42- with the new azaparacyclophane 2,5,8,11-tet raaza[12]paracyclophane (L2) has been studied by H-1, C-13 and Pt-195 NMR spectroscopy. Three different complexes are detected as a function of pH, all of them presenting cis-arrangement of nitrogen donors and chloride anions. In the first one, formed at acidic pH, the central ni trogen atoms of the macrocyclic are coordinating to Pt(II) while the b enzylic nitrogens remain protonated. Deprotonation of these nitrogens brings about a reorganisation of the complex, and the platinum is then coordinated by one benzylic nitrogen and the consecutive nitrogen in the macrocycle. This process can be monitored by NMR. Finally, additio n of a second mol of PtCl42- for each mole of L2 causes, most likely, the formation of a binuclear complex in which the tetraamine chain beh aves as two ethylenediamine subunits. The crystal structure of the add uct [PtBr4](2)[H(4)L1] has been solved by X-ray diffraction analysis ( space group P2(1)/c, a = 8.092(2), b = 16.049(2), c = 21.783(3) Angstr om, alpha = 90.00(1), beta = 100.34(2), gamma = 90.00(1)degrees, Z = 4 , R-1 = 0.0528, wR(2) = 0.1612). The compound is held together mainly through coulombic interactions between the charged polyammonium groups of the macrocycle and the PtBr42- anions as well as through an extens ive hydrogen bond network in which participate the bromides of the two PtBr42- anions and a lattice water molecule. (C) 1997 Elsevier Scienc e S.A.