Neutral dodecanuclear supramolecular complexes containing dimetal units linked by the trimesate anion

Two compounds having six metal-metal bonded Mo(2)(4+) and Rh(2)(4+) units, the midpoints of which occupy the vertexes of an octahedron, are described here. Each of the M(2)(4+) units is also bridged by two mutually cis formamidinate groups of the type DAniF = N,N'-di-p-anisylformamidinate. These units are linked to each other by four tricarboxylate anions from trimesic acid, the centers of which form a tetrahedron that is encapsulated by the octahedron of dimetal units. Each of the neutral cages has a clathrated solvent molecule, CH(2)Cl(2) when the metal M is Mo and CH(3)CN when it is Rh. For the latter, there are CH(3)CN molecules occupying (2)/(3) of the axial sites on the Rh(2) units in a way that reduces the symmetry. These symmetrical structures appear to persist in solution as shown by the (1)H NMR spectra. The compounds [M(2)(cis-DAniF)(2)](6)[1,3,5-C(6)H(3)(CO(2))(3)](4), 1 for M = Mo and 2 for M = Rh, were crystallized as 1.22.1CH(3)CN.2.3CH(2)Cl(2) and 2.13.9CH(3)CN, respectively. In 1 there are four crystallographically independent quadruply bonded Mo-Mo distances in the narrow range 2.098-2.104 A. For 2, the six independent singly bonded Rh-Rh distances are in the range 2.428-2.438 A.