(BETS)2[Fe(tdas)2]2: a new metal in the molecular conductor family.

The structure of bis[4,5-ethylenedithio-2-(4,5-ethylenedithio-1,3-diselenacyclopent-4-en-2-ylidene)-1,3-diselenacyclopent-4-enium] bis(mu-1,2,5-thiadiazole-3,4-dithiolato-kappa3S4,S5:S4)bis[(1,2,5-thiadiazole-3,4-dithiolato-kappa2S4,S5)iron(III)], (BETS)(2)[Fe(tdas)(2)](2) [BETS is alternatively called bis(ethylenedithio)tetraselenafulvalenium] or (C(10)H(8)S(4)Se(4))(2)[(Fe(C(2)N(2)S(3))(2))(2)], consists of segregated columns of dimers of BETS and columns of dimers of [Fe(tdas)(2)]. Each dimer displays inversion symmetry. Numerous chalcogen-chalcogen contacts are observed within and between the columns, producing a network of interactions responsible for the metal-like behaviour of the compound.

Structural and Magnetic Properties of M(mnt)(2) Salts (M = Ni, Pt, Cu) with a Ferrocene-Based Cation, [FcCH(2)N(CH(3))(3)](+). Interplay between M.M and M.S Intermolecular Interactions.

A series of metal bis-mnt complexes (mnt = 1,2-dithiolatomaleonitrile) with the trimethylammonium methylferrocene cation have been synthesized and characterized using X-ray diffraction, magnetic susceptibility, and differential scanning calorimetry measurements. The complexes have the formulas (FcCH(2)NMe(3))[Ni(mnt)(2)] (2), (FcCH(2)NMe(3))[Pt(mnt)(2)] (3), and (FcCH(2)NMe(3))(2)[Cu(mnt)(2)] (4) (where Fc = ferrocene). At 300 K, the crystal structures of 1:1 complexes 2 and 3 are very similar. They consist of pairs of [M(mnt)(2)](-) in a slipped configuration packed in stacks. Each [M(mnt)(2)](-) stack is separated from adjacent stacks by two columns of cations. Within the pairs, the [M(mnt)(2)](-) anions interact via short M.S contacts, while there are no short contacts between the pairs. Complex 4, which has a 2:1 stoichiometry, exhibits a markedly different packing arrangement of the anionic units. Due to the special position of the Cu atom in the asymmetric unit cell, [Cu(mnt)(2)](2)(-) dianions are completely isolated from each other. The magnetic susceptibility behavior of the nickel complex is consistent with the presence of magnetically isolated, antiferromagnetically (AF) coupled [Ni(mnt)(2)](-) pairs with the AF exchange parameter, J = -840 cm(-)(1). The platinum complex undergoes an endothermic structural phase transition (T(p)) at 247 K. Below T(p) its structure is characterized by the formation of magnetically isolated [Pt(mnt)(2)](2)(2)(-) dimers in an eclipsed configuration with short Pt.Pt and S.S contacts between monomers. In the magnetic properties, the structural changes reveal themselves as an abrupt susceptibility drop implying a substantial increase of the AF exchange parameter. A mechanism of the phase transition in the platinum compound is proposed. For compound 4, paramagnetic behavior is observed.

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

New precursors to potentially conductive noninteger oxidation state (NIOS) compounds based on metal complexes [ML(2)](n)()(-) [M = Ni, Pd, Pt; L = 5,6-dihydro-1,4-dithiin-2,3-dithiolato (dddt(2)(-)), 5,7-dihydro-1,4,6-trithiin-2,3-dithiolato (dtdt(2)(-)), and 2-thioxo-1,3-dithiole-4,5-dithiolato (dmit(2)(-)); n = 2, 1, 0] have been investigated. Complexes of the series (NR(4))[ML(2)] (R = Me, Et, Bu; L = dddt(2)(-), dtdt(2)(-)) have been isolated and characterized, and the crystal structure of (NBu(4))[Pt(dtdt)(2)] (1) has been determined {1 = C(24)H(44)NPtS(10), a = 12.064(2) Å, b = 17.201(3) Å, c = 16.878(2) Å, beta = 102.22(2) degrees, V = 3423(1) Å(3), monoclinic, P2(1)/n, Z = 4}. Oxidation of these complexes affords the corresponding neutral species [ML(2)](0). Another series of general formula (cation)(n)()[M(dmit)(2)] [cation = PPN(+), BTP(+), and (SMe(y)()Et(3)(-)(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)()Et(3)(-)(y)())(+)]. The crystal structures of (PPN)[Ni(dmit)(2)].(CH(3))(2)CO (2) and (SMeEt(2))[Ni(dmit)(2)] (3) have been determined {2 = C(45)H(36)NNiS(10)P(2)O, a = 12.310(2) Å, b = 13.328(3) Å, c = 15.850(3) Å, alpha = 108.19(3) degrees, beta = 96.64(2) degrees, gamma = 99.67(2) degrees, V = 2373(1) Å(3), triclinic, P&onemacr;, Z = 2; 3 = C(11)H(13)NiS(11), a = 7.171(9) Å, b = 17.802(3) Å, c = 16.251(3) Å, beta = 94.39(4) degrees, V = 2068(2) Å(3), monoclinic, P2(1)/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 x 10(-)(5) S cm(-)(1) at room temperature) {4 = C(20)H(8)Ni(2)PtS(28), a = 20.336(4) Å, b = 7.189(2) Å, c = 14.181(2) Å, beta = 97.16(2) degrees, V = 2057(1) Å(3), monoclinic, C2/m, Z = 2}. The crystal structures of the semiconducting NIOS compounds (BTP)[Ni(dmit)(2)](3) (5) and (SMe(3))[Ni(dmit)(2)](2) (6) have been determined {5 = C(43)H(22)PNi(3)S(30), a = 11.927(2) Å, b = 24.919(2) Å, c = 11.829(3) Å, alpha = 93.11(1) degrees, beta = 110.22(1) degrees, gamma = 83.94(1) degrees, V = 3284(1) Å(3), triclinic, P&onemacr;, Z = 2; 6 = C(15)H(9)Ni(2)S(21), a = 7.882(1) Å, b = 11.603(2) Å, c = 17.731(2) Å, alpha = 77.44(1) degrees, beta = 94.39(1) degrees, gamma = 81.27(1) degrees, V = 1563(1) Å(3), triclinic, P&onemacr;, Z = 2}. The parent compound (SEt(3))[Ni(dmit)(2)](z) (unknown stoichiometry) is also a semiconductor with a single-crystal conductivity at room temperature of 10 S cm(-)(1). By contrast, the single-crystal conductivity at room temperature of (SMeEt(2))[Pd(dmit)(2)](2) (7) is rather high (100 S cm(-)(1)). 7 behaves as a pseudometal down to 150 K and undergoes an irreversible metal-insulator transition below this temperature. The crystal structure of 7 has been determined {7 = C(17)H(13)NPd(2)S(21), a = 7.804(4) Å, b = 36.171(18) Å, c = 6.284(2) Å, alpha = 91.68(4) degrees, beta = 112.08(4) degrees, gamma = 88.79(5) degrees, V = 1643(1) Å(3), triclinic, P&onemacr;, Z = 2}. The electronic structure of (SMeEt(2))[Pd(dmit)(2)](2) (7) and the possible origin of the metal-insulator transition at 150 K are discussed on the basis of tight-binding band structure calculations.