NONVALENT INTERACTIONS IN THE CRYSTAL-STRUCTURES OF (ET(4)N)(2)[MO3S7BR6] AND (ET(4)N)(H9O4)[MO3S7CL6] CLUSTERS

Crystal structures of (Et(4)N)(2)[Mo3S7Br6] (I) and (Et(4)N)(H9O4)[Mo3 S7Cl6] (II) clusters belonging to the class of Mo3S74+ were determined by X-ray diffraction analysis. Crystals I are orthorhombic, a = 19.10 6(3), b = 12.930(2), c = 29.887(5) Angstrom, V = 7383(2) Angstrom(3), space group Pbca, Z = 8, d(calc) = 2.253 g/cm(3), R(F) = 0.0402, wR(F- 2) = 0.0587 for 2493 F-hkl > 4 sigma. Crystals II are monoclinic, a = 17.106(3), b = 18.882(4), c = 11.006(2) Angstrom, beta = 226.13(3)degr ees, V = 2871.2(9) Angstrom(3), space group Cc, Z = 4, d(calc) = 2.147 g/cm(3), R(F) = 0.0181, wR(F-2) = 0.0445 for 2307 F-hkl > 4 sigma. St ructure I has an anion dimer with 3S(ax)...Cl = 3.258(4)-3.404(4) Angs trom; the dimer is similar to that observed in the structures of A(2)[ M(3)X(7)Hal(6)], A = Ph(4)P(+), Ph(3)EtP(+), and PPN+. In structure II , infinite chains of anions bonded by 3S(ax)...Cl contacts of 3.183(3) -3.394(3) Angstrom were found. A similar phenomenon was established ea rlier for the structure of (Et(4)N)(H9O4)[Mo3S7Br6] (III), which is no r isostructural to II. Compounds II and III also differ in the structu re of the H9O4+ Cation: infinite helix in II and pyramid in III.