SYNTHESIS AND STRUCTURE OF A NOVEL SILVER(I) PERCHLORATE 2,2'/6',2''-TERPYRIDINE ADDUCT SOLVATED WITH ACETONITRILE

Recrystallization of an equimolar mixture of silver(I) perchlorate and 2,2':6',2''-terpyridine (terpy) from acetonitrile solution yields the golden yellow crystalline adduct shown by a room-temperature single-crystal X-ray study to be [Ag3(terpy)4][(MeCN)Ag(terpy)] (ClO4)4. Crystals are triclinic, P1BAR, a 21.48(l), b 14.525(7), c 13.506(8) angstrom, a 68.50(4), beta 80.71(4), gamma 81.66(4)-degrees, Z 2 formula units; R was 0.045 for 9681 'observed' reflections. The complex helical cation is quasi-centrosymmetric with a collinear Ag3 array. The environment of the central silver atom is planar four-coordinate, two short Ag-N distances [(2.198(5), 2.188(5) angstrom] arising from the nitrogen atoms of outer rings of a pair of twisted terpy ligands; the other two sites are occupied by the nitrogen atoms of the central terpy rings which bifurcate to the other silver atoms [Ag(central)-N(central) 2.624(5), 2.818(5) angstrom; Ag(outer)-N(central) 2.704(4), 2.640(4) angstrom], which are also coordinated by the outer ring nitrogen of the two ligands [Ag-N, 2.266(5), 2.304(4) angstrom]. Coplanar with the latter, each outer silver atom has a further tridentate terpy coordinated [Ag-N(central) 2.362(4), 2.381(4) angstrom; Ag-N(outer) 2.403(6)-2.573(5) angstrom]. The [(MeCN)Ag(terpy)]+ species is also quasi-planar, Ag-NCMe being 2.174(7) angstrom, opposed to the central ring nitrogen [2.331(5) angstrom; Ag-N(outer) being 2.399(7), 2.433(7) angstrom].