COCRYSTALLIZATION OF ORGANOMETALLIC CLUSTERS - HOMOMOLECULAR AND HETEROMOLECULAR CRYSTALS OF RU6C(CO)14(ETA(6)-C6H4ME2) AND RU6C(CO)11(ETA(6)-C6H4ME2)2

The molecular structure of Ru6C(CO)11(eta6-C6H4Me2)2 (2) has been established by the single crystal X-ray diffraction method in its crystalline form B. The species has also been found to cocrystallize with Ru6C(CO)14(eta6-C6H4Me2) (1), and the structure of the heteromolecular cocrystal C has been determined. A homomolecular crystal of 1 (crystal A) had been discovered previously. The mono- and bis(xylene) derivatives in their homo- and heteromolecular crystals have been compared in terms of molecular and crystal structure, intermolecular interlocking, and packing potential energies. Crystal B, containing only molecules of type 2, is monoclinic, space group Pn, a = 10.242(3) angstrom, b = 14.047(6) angstrom, c = 11.242(2) angstrom, beta = 106.15(2)-degrees, V = 1553.6(9) angstrom3, Z = 4. Cocrystal C, formed by 1 and 2, is triclinic, space group P1BAR, a = 9.852(4) angstrom, b = 10.444(9) angstrom, c = 32.320(10) angstrom, alpha = 95.65(6)-degrees, beta = 92.03(4)-degrees, gamma = 115.29(4)-degrees, V = 2981(3) angstrom3, Z = 2 on each molecular unit. It has been shown that a precise relationship exists between the crystal structures of the homomolecular crystals A and B and that of the heteromolecular crystal C, the last being essentially formed by bimolecular layers similar to those present in the separate crystals. The three crystal forms also compare strictly in terms of packing efficiency and crystal cohesion.