SYNTHESIS AND STRUCTURE OF CROWN-ETHER COMPLEXES OF POTASSIUM HEXACHLORODIPALLADATE(II) AND HEXACHLORODIPLATINATE(II)

K-2[MCl4] (M = Pd, Pt) reacts with an excess of crown ether 18-crown-6 in water to give the crown ether complexes of potassium hexachlorodip alladate(II) and -diplatinate(II) [K(18-cr-6)](2)[M2Cl6] (M = Pd, 1; M = Pt, 3), respectively, and in methylene chloride to give those of po tassium tetrachloropalladate(II) and -platinate(II) [K(18-cr-6)](2)[MC l4] (1) (M = Pd, 2; M = Pt, 4), respectively. 1-4 are characterized by microanalysis, NMR (H-1, C-13), and vibrational spectroscopy. The X-r ay structure analyses of the isotypic complexes 1 (P2(1)/c; a = 10,967 8(8), b = 8,2991(7), c = 22,469(2) Angstrom, beta = 98,523(5)degrees; Z = 2) and 3 (P2(1)/c; a = 10,934(3), b = 8,376(3), c = 22,410(5) Angs trom, beta = 98,77(3)degrees; Z = 2) reveal [M2Cl6](2-) anions of near ly D-2h symmetry and [K(18-cr-6)](+) cations, in which the distance of K+ to the mean plane of the crown ether defined by its six oxygen ato ms amounts to 0,830(4) Angstrom in 1 and 0,821(2) Angstrom in 3, respe ctively. There are tight contacts between cations and anions (d(K-Cl): 3,341(2)/3,260(2) Angstrom (1); 3,348(4)/3,259(4) Angstrom (3)).