Structural studies on [Mo3S4](4+) and [Mo3S4Cu](4+) complexes with tripodal ligands providing various NxOy(x+y=3) donor sets

The interaction of 1,3,5-triamino-1,3,5-trideoxy-cis-inositol (taci) and its N-methylated derivative 1,3,5-trideoxy-1,3,5-tris(dimethylamino)-cis-inositol (tdci) with the incomplete [Mo3S4](4+) cube and the heterometallic [Mo3S4Cu](4+) cube have been investigated by X-ray analysis. The crystal structures of [Mo3S4(taci+C3H6O-H2O)(3)-4H]. 20H(2)O (1a, rhombohedral, space group R32, a=15.964(3), c=40.59(1) Angstrom, Z= 6), [Mo3S4(tdci)(3)]Br-4 . 9.5EtOH . 5H(2)O (2a, triclinic, space group P (1) over bar, a=15.166(7), b=17.372(7), c=18.362(6) Angstrom, alpha=103.68(3), beta=102.34(4), gamma=102.96(4)degrees,Z=2) and [CuBrMo3S4(tdci)(3)]Br-3 . 11 H2O . EtOH (3a, monoclinic, space group P2(1)/n, a=14.887(3), b=22.570(4), c=21.974(5) Angstrom, beta=98.54(2)degrees,Z=4) revealed an N-N-O and an N-O-O coordination mode for taci and tdci, respectively. In 1a, taci is coordinated as an anion with deprotonated oxygen and nitrogen donors. In addition, the noncoordinating amino group reacted with one equivalent of acetone, forming a Schiff base condensation product. For 2a, short Mo-O bonds and high pK(a) values (compared to the aqua ion [Mo3S4(H2O)(9)](4+)) indicate the formation of a zwitterionic form of the tdci ligand with coordinated alkoxo groups and peripheral dimethylammonium groups. No significant differences were found for the structural properties of the Mo-tdci fragment in 2a and 3a. The coordination modes of taci and tdci, as observed in the solid state, are in agreement with the previously reported solution structures, established by NMR spectroscopy. They are attributed to the specific steric requirements of the two ligands and to a pronounced preference of the [Mo-3(mu S)(3)(mu(3)S)](4+) core to coordinate a nitrogen donor trans to mu(3)S.