Self-assembly of high-nuclearity metal clusters:: Programmed expansion of a metallasiloxane cage to an octacopper(II) cluster

The novel octanuclear copper(II) cluster [Cu-6{(PhSiO2)(6)}(2){NCCu-(Me(6)tren)}(2)(MeOH)(4) ](2+) (1) has been isolated as a perchlorate salt by reacting the hexacopper(II) metallasiloxane cage [Cu-6{(PhSiO2)(6)}(2)(nBuOH)(x)] (x = 4, 6) with [Cu(Me(6)tren)CN]CIO4 in a methanol/chloroform mixture (Me(6)tren = tris(2-(dimethylamino)ethyl) amine). Crystal data for 1(ClO4)(2).MeOH: monoclinic, space group P2(1)/n (no. 14), a = 16.8490(3) Angstrom, b = 22.2966(4) Angstrom, c = 17,2508(3) Angstrom, beta = 94.7658(5)degrees, V = 6458.3(2) Angstrom(3), Z = 2. The structure comprises a highly distorted hexagonal Cu-6 array linked to two [Cu(Me(6)tren)] units via cyanide bridges. Magnetic measurements reveal that the addition of the copper cyanide complexes dramatically affects the magnetism of the Cu-6 unit, whose ground spin state changes from S = 3 to S = 0.