Metal Complexes of Dithiolate Ligands:  5,6-Dihydro-1,4-dithiin-2,3-dithiolato (dddt2-), 5,7-Dihydro-1,4,6-trithiin-2,3-dithiolato (dtdt2-), and 2-Thioxo-1,3-dithiole-4,5-dithiolato (dmit2-). Synthesis, Electrochemical Studies, Crystal and Electronic Structures, and Conducting Properties

New precursors to potentially conductive noninteger oxidation state (NIOS) compounds based on metal complexes [ML2] n - [M = Ni, Pd, Pt; L = 5,6-dihydro-1,4-dithiin-2,3-dithiolato (dddt2-), 5,7-dihydro-1,4,6-trithiin-2,3-dithiolato (dtdt2-), and 2-thioxo-1,3-dithiole-4,5-dithiolato (dmit2-); n = 2, 1, 0] have been investigated. Complexes of the series (NR4)[ML2] (R = Me, Et, Bu; L = dddt2-, dtdt2-) have been isolated and characterized, and the crystal structure of (NBu4)[Pt(dtdt)2] (1) has been determined {1 = C24H44NPtS10, a = 12.064(2) Å, b = 17.201(3) Å, c = 16.878(2) Å, β = 102.22(2)°, V = 3423(1) Å3, monoclinic, P21/n, Z = 4}. Oxidation of these complexes affords the corresponding neutral species [ML2]0. Another series of general formula (cation) n [M(dmit)2] [cation = PPN+, BTP+, and (SMe y Et3 - y )+ with y = 0, 1, 2, and 3, n = 2, 1, M = Ni, Pd] has also been studied. All of these (cation) n [M(dmit)2] complexes have been isolated and characterized [with the exception of (cation)[Pd(dmit)2] for cation = (SMe y Et3 - y )+]. The crystal structures of (PPN)[Ni(dmit)2]·(CH3)2CO (2) and (SMeEt2)[Ni(dmit)2] (3) have been determined {2 = C45H36NNiS10P2O, a = 12.310(2) Å, b = 13.328(3) Å, c = 15.850(3) Å, α = 108.19(3)°, β = 96.64(2)°, γ = 99.67(2)°, V = 2373(1) Å3, triclinic, P1̄, Z = 2; 3 = C11H13NiS11, a = 7.171(9) Å, b = 17.802(3) Å, c = 16.251(3) Å, β = 94.39(4)°, V = 2068(2) Å3, monoclinic, P21/n, Z = 4} NIOS salts derived from the preceding precursors were obtained by electrochemical oxidation. Electrochemical studies of the [M(dddt)2] complexes show that they may be used for the preparation of NIOS radical cation salts and [M(dddt)2][M‘(dmit)2] x compounds, but not for the preparation of (cation)[M(dddt)2] z NIOS radical anion salts. The electrochemical oxidation of the [M(dtdt)2]- complexes always yields the neutral [M(dtdt)2]0 species. The crystal structure of [Pt(dddt)2][Ni(dmit)2]2 (4) has been determined and is consistent with the low compaction powder conductivity (5 × 10-5 S cm-1 at room temperature) {4 = C20H8Ni2PtS28, a = 20.336(4) Å, b = 7.189(2) Å, c = 14.181(2) Å, β = 97.16(2)°, V = 2057(1) Å3, monoclinic, C2/m, Z = 2}. The crystal structures of the semiconducting NIOS compounds (BTP)[Ni(dmit)2]3 (5) and (SMe3)[Ni(dmit)2]2 (6) have been determined {5 = C43H22PNi3S30, a = 11.927(2) Å, b = 24.919(2) Å, c = 11.829(3) Å, α = 93.11(1)°, β = 110.22(1)°, γ = 83.94(1)°, V = 3284(1) Å3, triclinic, P1̄, Z = 2; 6 = C15H9Ni2S21, a = 7.882(1) Å, b =