Neutral Dodecanuclear Supramolecular Complexes Containing Dimetal Units Linked by the Trimesate Anion

Two compounds having six metal−metal bonded Mo24+ and Rh24+ units, the midpoints of which occupy the
vertexes of an octahedron, are described here. Each of the M24+ 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, CH2Cl2 when the
metal M is Mo and CH3CN when it is Rh. For the latter, there are CH3CN molecules occupying 2/3 of the axial
sites on the Rh2 units in a way that reduces the symmetry. These symmetrical structures appear to persist in
solution as shown by the 1H NMR spectra. The compounds [M2(cis-DAniF)2]6[1,3,5-C6H3(CO2)3]4, 1 for M =
Mo and 2 for M = Rh, were crystallized as 1·22.1CH3CN·2.3CH2Cl2 and 2·13.9CH3CN, respectively. In 1 there
are four crystallographically independent quadruply bonded Mo−Mo distances in the narrow range 2.098−2.104
Å. For 2, the six independent singly bonded Rh−Rh distances are in the range 2.428−2.438 Å.