Vanadium, molybdenum, and sodium triethanolamine complexes derived from anassembly system containing tetrathiometalate and triethanolamine

The reaction system composed of triethanolamine (TEA) and tetrathiovanadate in the presence of MeONa (MeOLi) or NaNH2 was studied to afford vanadium a nd alkali metal TEA complexes. Complexes {M subset ofV(6)O(6)[N(CH2CH2O)(2) (CH2CH2OH)](6)}(2)S-6 (M = Na (1), Li (2)) contain two cyclic V-(IV) [12]me tallacrown-6 cations linked by a polysulfide S-6(2-) anion. Also separated from the reaction system is a novel sodium TEA complex {[Na(TEA)](2)S-6}(n) , (3), in which parallel coordination chains [Na(TEA)(+)](n) are connected by O-H . . .S hydrogen bonds forming 3-D network structure. Variable-temper ature conductance of 3 was determined to display semiconductor feature. The desulfurization of VS43- was observed to form S-6(2-) anion and,or S-8 mol ecule in the synthetic reactions of 1-3. A striking contrast was noted that MoS42- did not desulfurize in the similar reaction to that of VS43- With T EA, and a Na/TEA complex containing MoS42-, (Et4N)(2)[Na-2(mu -TEA)(2)(CH3O H)(2)](MoS4)(2) (4), was Obtained instead. The S . . .H-O and O . . .H-O hy drogen bonds play an important role in forming the one- or three-dimensiona l structures for all these complexes by the linkages between clusters and c hains. The IR spectrum indicates the structural similarity of complexes 1 a nd 2. For complex 4, the Mo=S stretch vibration at 468 cm(-1) showing widen ing and slight red-shift and the slight movement of the H-1 NMR signals of TEA ligand to downfield are considered to be the influence of the S . . .H- O hydrogen bonds. Variable temperature magnetic susceptibility data were co llected for complex 1. The effect magnetic moment per V-6 unit varies gradu ally from 4.04 mu (B) at 300 K to 6.24 mu (B) at 5 K, exhibiting ferromagne tic interaction. Heisenberg-type vector-coupling model and molecular field approximation were used to treat the interaction between the paramagnetic s ites and gave a good fitting result: J = 3.97 cm(-1), J ' = 1.99 cm(-1), g = 1.99, F = 3.64 x 10(-3). Density functional calculation was also performe d to complex 1 and its Li, K analogues. The lowest total bonding energy of -874.001 eV was obtained for [Na subset ofV(6)(mu (3)-O)(6)] complex contai ning six unpaired electrons, indicating the stability of a V-6 system with six independent spins S = 1/2. When the alkali metal ion is inserted into t he [V-6(mu (3)-O)6] cavity, the positive values of the bonding interaction (E-b) indicate that the insertion depresses the total energy and that compl exes 1 and 2 together with K+ complex may exist. However, the lowest E-b va lue of the K+ complex implies its instability.