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We report the preparation, crystallization, and solid-state characterization of a benzyl-substituted spirobiphenalenyl radical. The crystal structure shows that the radical is monomeric in the solid state, with the molecules packed in an unusual one-dimensional (1-D) fashion that we refer to as a pi-step stack. This particular mode of 1-D stacking is forced on the lattice arrangement by the presence of the orthogonal phenalenyl units that were specifically incorporated to prevent the crystallization of low-dimensional structures. The structure shows that this strategy is effective, and neighboring molecules in the stack can only interact via the overlap of one pair of active (spin-bearing) carbon atoms per phenalenyl unit, leading to the pi-step structure in which the remaining four active carbon atoms per phenalenyl unit do not interact with nearest neighbor molecules. The magnetic susceptibility data in the temperature range 4-360 K may be fit to an antiferromagnetic Heisenberg S = 1/2 linear chain model with intrachain spin coupling J = -52.3 cm(-1). Despite the uniform stacking, the material has a room temperature conductivity of 1.4 x 10(-3) S/cm and is best described as a Mott insulator.

A simple and general route to the synthesis of cobaloxime with mixed dioxime ligands, XCo(L)(L′)Py, L,L′=dmgH/dpgH and chgH/dpgH; X=Cl, Br, NO2, N3, has been described. These compounds are reported for the first time. The synthesis is confirmed by the X-ray structures of N3Co(dmgH)(dpgH)Py and N3Co(chgH)(dpgH)Py. The cis and trans effects on these complexes and on XCo(L)2Py (L=dmgH, chgH, dpgH; X=Cl, Br, NO2, N3) complexes have been studied by 1H-, 13C-NMR, UV, and X-ray. For a range of X ligands, a clear trend between the 1H, 13C chemical shifts of the equatorial and axial ligands as well as with the Co–dioxime CT band has been observed. The analysis of the 13C values and X-ray data shows that one dioxime wing effects the other dioxime wing in the mixed dioxime complexes.

We report the preparation, crystallization, and solid-state characterization of ethyl (3)- and butyl (4)-substituted spiro-biphenalenyl radicals. Both of these compounds are found to be conducting face-to-face pi-dimers in the solid state but with different room-temperature magnetic ground states. At room temperature, 4 exists as a diamagnetic pi-dimer (interplanar separation of approximately 3.1 A), whereas 3 is a paramagnetic pi-dimer (interplanar separation of approximately 3.3 A), and both compounds show phase transitions between the paramagnetic and diamagnetic forms. Electrical resistivity measurements of single crystals of 3 and 4 show that the transition from the high-temperature paramagnetic pi-dimer form to the low-temperature diamagnetic pi-dimer structure is accompanied by an increase in conductivity by about 2 orders of magnitude. This behavior is unprecedented and is very difficult to reconcile with the usual understanding of a Peierls dimerization, which inevitably leads to an insulating ground state. We tentatively assign the enhancement in the conductivity to a decrease in the on-site Coulombic correlation energy (U), as the dimers form a super-molecule with twice the amount of conjugation.

A synthetic scheme leading to the (X)(Y)bis(1,2-cyclohexanedionedioximato)cobalt(III) complexes, where X=Cl, N 3 , ClCH 2 , CH 3 , C 2 H 5 and Y=PPh 3 and Py is reported. The complexes have been characterized by the usual spectroscopic techniques and have been compared with the reported analogous compounds having other dioximes as the equatorial ligands. The first crystal structure of an inorganic cobaloxime with 1,2-cyclohexanedionedioxime (Nioxime) is reported. For a range of X ligands, a clear trend between 31 P, 13 C, 1 H chemical shifts of the equatorial and axial ligands as well as with the Co→chgH charge transfer band has been observed.

The reactions of chlorocyclophosphazenes N3P3Cl6 (1) and N4P4Cl8 (2) and polydichlorophosphazene (3) with cyclohexylamine, cyclopentylamine, and cyclopropylamine have been studied. The major product with 1 is the geminal tetrakis derivative N3P3Cl2(NHR)4, while 2 gives the completely substituted derivative, N4P4(NHR)8. X-ray crystal structure determinations of N3P3Cl2(NHC6H11)4 (1a) and N4P4(NHC3H5)8 (2c) have been carried out. 1a crystallizes in a triclinic space group, P1, with a = 11.2330(13) A, b = 11.4269(16) A, c = 13.4055(12) A, α = 72.211(10)°, β = 72.150(9)°, γ = 81.777(11)°, V = 1557.3(3) A3, and Z = 2. 2c crystallizes in a monclinic space group, P21/n, with a = 12.433(3) A, b = 20.484(4) A, c = 12.645(3) A, β = 92.81(2)°, V = 1557.3(3) A3, and Z = 4. The cycloalkylamino-substituted polyphosphazenes contain a small amount of residual chlorine atoms. These have high glass transition temperatures.

The structure of 4,4'-bipyridinium diiodide has been determined. The diprotonated cation possesses crystallographic inversion symmetry with the pyridyl rings coplanar. The crystal packing is dominated by weak but directional N-H···I (N···I distance of 3.47(2) A) and C-H···I (C···I distances of 3.74(3)3.77(3) A) interactions to give layers of ions. The layers stack parallel to the (101) direction and are linked together by an additional C-H···I interaction (C···I distance of 3.816(5) A). Crystal data: triclinic, P-1 (No. 2), a = 8.2940(13), b = 8.3842(11), c = 5.0978(8) A, a = 93.761(11)°, s = 112.281(12)°, ? = 106.887(11)°, V = 307.63(8) A3, Z = 1, Scalc = 2.22 g/cm3. Final residual values based on 997 observed (I > 2s(I)) reflections: R = 0.026, Rw = 0.034.

The synthesis of dicyanooligothiophenes NC(C4H2S)nCN (n = 3−6) is reported. For n = 3, 4, and 5 the dinitriles are generated by treatment of the corresponding dibromo compounds with copper(I) cyanide in quinoline. For n = 6 the preparation involves the Ni-catalyzed coupling of 5-bromo-2,2‘:5‘,2‘‘-terthiophene-5‘‘-carbonitrile. The structures of all four dicyano derivatives have been determined by X-ray crystallography. For n = 3, the space group is monoclinic C2/c, with a = 18.363(7), b = 11.8356(9), c = 30.666(4) A, β = 102.15(2)°, V = 6515(3) A3, Z = 20. For n = 4 the space group is triclinic P1, a = 7.3254(9), b = 7.8658(6), c = 8.1813(8) A, α = 64.706(8), β = 76.059(8), γ = 76.692(8)°, V = 409.29(7) A3, Z = 1. For n = 5 the space group is monoclinic C2/c, with a = 13.633(4), b = 11.706(5), c = 37.073(8) A, β = 90.22(2)°, V = 5929(3) A3, Z = 12. For n = 6, the space group is monoclinic P21/a, with a = 13.8962(14), b = 5.9100(16), c = 14.0798(16) A, β = 98.446(4)°, V = 1143.8(4) A3, Z = 2. In all four ...

Electroreduction of 1,3- and 1,4-benzene-bridged bis(diselenadiazolium) salts [1,4-Se][SbF6]2 and [1,4-Se][SbF6]2 in acetonitrile, at a Pt wire and in the presence of iodine affords the 1:1 charge-transfer salts [1,4-Se][I] and [1,3-Se][I]. Crystals of [1,4-Se][I] belong to the monoclinic space group C2/m, with FW = 598.9, a = 10.586(2), b = 16.713(2), c = 3.5006(14) A, β = 104.26(2)°, V = 600.2(3) A3, Z = 2. Crystals of [1,3-Se][I] belong to the orthorhombic space group Ima2, with FW = 598.9, a = 28.489(7), b = 3.543(2), c = 12.283(2) A, V = 1239.8(8) A3, Z = 4. In the presence of an excess of iodine, electrocrystallization of [1,4-Se]2+ affords the mixed iodide/triiodide salt [1,4-Se][I][I3], space group C2/c, FW = 979.59, a = 12.862(3), b = 15.063(2), c = 9.028(3) A, β = 100.62(2)°, V = 1719.1(7) A3, Z = 4. The structures of the two 1:1 compounds consist of perfectly superimposed stacks of molecular units interspersed by columns of disordered iodines. Interstack contacts in both structures are limited,...

Cosublimation of 2,5-furanbis(1,2,3,5-dithiadiazolyl) [F-2,5-S] and iodine affords 1:1 and 2:1 charge-transfer salts, [F-2,5-S][I] and [F-2,5-S]2[I]. Cosublimation of 2,6-pyridinebis(1,2,3,5-dithiadiazolyl) [P-2,6-S] and iodine affords uniquely the 2:1 charge-transfer salt [P-2,6-S]2[I]. Crystals of the latter belong to the space group P21/c, a = 3.434(3), b = 9.8914(9), c = 30.803(4) A, β = 91.52(3)°, V = 1045.9(9) A3, Z = 2. The structure consists of [P-2,6-S] molecules stacked along the x direction. Pairs of stacks are linked head-on through iodine atoms, which themselves form disordered stacks running parallel to x. The internal structural parameters of the two CN2S2 rings within each molecule suggest that one (linked to iodine) is formally uncharged, while the other is partially oxidized. This latter ring is heavily coordinated through S- - -N linkages to neighboring CN2S2 rings and pyridine. Magnetic susceptibility measurements on [P-2,6-S]2[I] indicate that it is diamagnetic below 220 K.

Synthesis and spectroscopy of four heterobimetallic compounds containing the metal centres Cu(II)-Pd(II) and Cu(II)-Pt(II) with the multidentate nitrogen donor ligand hexakis (3,5-dimethyl-pyrazolyl)cyclotriphosphazene, (HPCTP) are reported. The complexes HPCTP·CuCl2·MX2 (M = Pd, X = Cl (3) or Br (4) and M = Pt, X = Cl (5) or Br (6)) were obtained by treating the metal-containing ligands HPCTP°CuX2 X = Cl(l) or Br(2)) with M(PhCN)2Cl2(M = Pd or Pt). The electronic absorption spectra and electron paramagnetic resonance data indicate the copper in these compounds has a distorted trigonal bipyramidal geometry. A single crystal X-ray determination of 4 is reported. The crystals of 4 are monoclinic with a = 10.570(2), b = 28.863(4), c = 16.009(1)A, β = 98.71(2)°, V = 4827(1)A3, Z = 4, D c = 1.65 g cm−3 and space group P21/c. The geometry about copper is trigonal bipyramidal with mean distances of Cu-N(pz) = 1.987(13), Cu-N(ctp) = 2.352(11) and Cu-Cl = 2.315(10)A while that of palladium is square plana...

The isolation and characterization of the trimethylenesulfide-coordinated complex, [CpRu(PPh3)2(SC3H6)]CF3SO3, is reported. The structure of [CpRu(PPh3)2(SC3H6)]CF3SO3 was determined by X-ray diffraction techniques: monoclinic space group I2/a, a=23.864(10), b=14.233(3), c=24.385(7) A, β=97.10(3)°, Z=8, R=0.046, Rw=0.065. The Ru is attached to two triphenylphosphine ligands, a cyclopentadienyl and the trimethylenesulfide. The Ru-S distance is 2.3459(20) A.

4-CF3—C6H4—CN3S2, 1, forms symmetrical sulfur-bound adducts with norbornene (NBE), norbornadiene (NBD), and 1-heptene (C7H14), which were studied by 1H, 13C, COSY-45, and HETCORR NMR. 1•NBE exists in solution in a single isomeric form which corresponds to that found in the solid state for 4-CH3O—C6H4—CN3S2•NBE by single-crystal X-ray diffraction: orthorhombic, P212121 with Z = 4, a = 10.224(3), b = 10.369(5), c = 14.075(5). R = 0.0475 and Rw = 0.0492 for 634 data. 1•NBD exists in solution in two isomeric forms which are not interchangeable. One of these corresponds to that found in the NBE adduct, i.e. exo addition; the other is the first example of endo addition. Two bis adducts of stoichiometry NBD•21 have been prepared and separated. They are isomers exhibiting exo-exo and exo-endo addition. The structure of the latter was confirmed by X-ray diffraction: orthorhombic, Pcab with Z = 8, a = 7.816(2), b = 17.264(3), c = 36.842(5). R = 0.068 and Rw = 0.106 for 1506 data. 1•C7H14 exists as a mixture of syn and anti isomers. NMR structure parameters derived here have been applied to published data on over 15 thiazene NBE and NBD adducts.

The structure of the [CpRu(PPh[sub 3])[sub 2](t[minus]C[sub 4]H[sub 4]SH)]BF[sub 4] complex was determined by X-ray diffraction techniques; monoclinic space group P2[sub 1]/c, a = 14.662(9), b = 18.515(7), c = 15.368(6) [angstrom], [beta] = 101.88(5)[degrees], V = 4082(6) [angstrom][sup 3], Z = 4, R = 0.049, R[sub w] = 0.057. The Ru is attached to two triphenylphosphine ligands, a cyclopentadienyl and the t-butylmercaptan. The Ru-S distance is 2.396(2)[angstrom] and the S-H distance is 1.289(2)[angstrom].

The reactions of N,N,N[prime]-tris(trimethylsilyl)formamidine with ECl[sub 2] (E = S, Se) afford 1,2,3,5-dithia- and 1,2,3,5-diselenadiazolium chloride, which can be reduced with triphenylantimony to the corresponding dithia- and diselenadiazolyl radicals [HCN[sub 2]E[sub 2]]. The solid state structure of the cofacial dimer [HCN[sub 2]S[sub 2]][sub 2] has been determined by X-ray diffraction; crystals of [HCN[sub 2]S[sub 2]][sub 2] belong to the monoclinic space group P2[sub 1]/n, with a = 6.833(6), b = 16.463(4), c = 19.161(4) A, [beta] = 93.57(4)[degrees], FW = 210.30, Z = 12. The crystal structure consists of stacked dimers, with three dimers in the asymmetric unit. Along the stacking axis the mean intradimer S---S contact is 3.11 A; the mean interdimer contact is 3.76 A. Ab initio calculations with split-valence and larger basis sets have been employed to evaluate the structures and energies of both the gas phase radicals and their dimers. Minor changes in geometry are predicted upon association of the monomers; this relative structural invariance is consistent with low binding energies, the best predictions (including zero point vibrational energy corrections) being ca. 4 kcal/mol (for E = S) and ca. 10 kcal/mol (for E = Se). 30 refs., 6 figs., 9 tabs.

The preparation and solid-state characterization of the 1,3,5-triazine-bridged tris(1,2,3,5-ditliiadiazolyl) complex 4,4',4''-(2,4,6-(1,3,5-triazinetriyl))tris(1,2,3,5-dithiadiazolyl) [N 3 C 3 (CN 2 S 2 ) 3 ] are described. The crystals belong to the monoclinic space group C2/c, with a=20.759(7) A, b=10.525(3) A, c=17.554(3) A, β=140.18(4) o , fw=390.5, Z=8, and V=2456.2(12) A 3 . The crystal structure consists of layers of interlocked dimers. Alternate layers are oriented in an antiparallel fashion, thereby precluding a stacked structure similar to that found in the related 1,3,5-benzene-based triradical. There are two dimerization environments

The isolation and characterization of two mercaptan complexes of the general formula [CpRu(PPh3)2(RSH)]BF4, where R=benzyl and phenethyl, were undertaken to model the substrate/catalyst interaction of the hydrode-sulfurization (HDS) process. The IR data show a shift in the SH stretching frequency upon coordination. The structure of the [CpRu(PPh3)2(C6H5CH2CH2SH)]BF4 complex was determined by X-ray diffraction techniques: monoclinic space group P21/n, a=15.317(4), b=13.924(9), c=21.815(7) A, β=95.20(2)°, Z=4, R=0.057, Rw=0.073. The Ru is attached to two triphenylphosphine ligands, a cyclopentadienyl and the phenethylmercaptan. The Ru-S distance is 2.369(2) A and the S-H distance is 1.18 A.

The title molecule, 3,7-bis(2-thienyl)-1,5,2,4,6,8-dithiatetrazocine, C 10 H 6 N 4 S 4 , is planar within 0.069 (5) A and crystallizes in the monoclinic space group P2 1 /c. There are two centrosymmetric molecules in the cell; these are stacked such that each eight-membered C 2 N 4 S 2 ring has a thienyl ring above and below it. The mean interplanar separation is 3.55 (2) A.

The preparation and solid-state characterization of the dimers of the cyanophenyl-substituted 1,2,3,5-dithia- and 1,2,3,5-diselenadiazolyl radicals [NCC6H4CN2E2]· (E = S, Se) are described. Crystals of the 4-cyanophenyl derivatives 4 are triclinic, space group P¯1. The radicals dimerize in a cofacial fashion, with mean intradimer E- - -E spacings of 3.104/3.233 Å (E = S/Se). The dimer units form ribbonlike arrays connected by head-to-tail CN- - -E contacts. The ribbons are packed in an antiparallel fashion with no close interdimer E- - -E contacts. The 3-cyanophenyl sulfur derivative 5 crystallizes in two phases. The α-phase, along with the isomorphous selenium compound, belongs to the monoclinic space group P21/n. As in the 4-cyano derivatives, the radicals dimerize cofacially, generating ribbons connected by head-to-tail CN- - -E contacts. The ribbons, however, are layered with CN2E2 rings oriented into stacks parallel to the a axis. In addition to short intradimer E- - -E contacts (mean values = 3.13 (2)/3.27 (4) Å for E = S/Se), there are relatively short interdimer E- - -E contacts (mean values = 4.26 (5)/4.15 (5) Å (E = S/Se) along the stacking axis. The β-phase of the 3-cyanophenyl sulfur compound 5, monoclinic space group P21/n, forms discrete dimers associated in a trans antarafacial fashion, with intradimer S- - -S contacts of 3.121 (1) Å; there are no close interdimer S- - -S contacts. The 2-cyanophenyl selenium derivative 6 crystallizes in the polar space group P21. In this structure also the dimer units are laced together by short CN- - -Se contacts. The dimers form stacks parallel to the b axis, with mean intradimer and interdimer Se- - -Se contacts of 3.312/4.083 Å, respectively. Lattice constants for the six structures are: 4 (E = S), C8H4N3S2, a = 10.466 (3) Å, b = 10.342 (2) Å, c = 9.169 (2) Å, α = 104.97 (2)°, β = 112.97 (2)°, γ = 69.84 (2)°, V = 849.0 (3) Å3, Z = 4; 4 (E = Se), C8H4N3Se2, a = 10.478 (4) Å, b = 10.780 (4) Å, c = 9.432 (4) Å, α = 107.16 (3)°, β = 115.23 (2)°, γ = 68.39 (3)°, V = 883.8 (6) Å3, Z = 4; 5 (E = S, α-phase), C8H4N3S2, a = 7.295 (3) Å, b = 20.488 (2) Å, c = 11.276 (2) Å, β = 95.54 (2)°, V = 1676.0 (7) Å3, Z = 8; 5 (E = Se), C8H4N3Se2, a = 7.364 (8) Å, b = 21.085 (2) Å, c = 11.119 (4) Å, β = 94.91 (5)°, V = 1720 (7) Å3, Z = 8; 5 (E = S, β-phase), C8H4N3S2, a = 8.782 (1) Å, b = 5.638 (1) Å, c = 17.128 (4) Å, β = 102.94 (2)°, V = 826.5 (6) Å3, Z = 4; 6 (E = Se), C8H4N3Se2, a = 7.301 (1) Å, b = 11.883 (2) Å, c = 10.186 (1) Å, β = 101.50 (1)°, V = 866.1 (5) Å3, Z = 4.

The solid-state characterization of a second or β-phase of the 1,3-phenylene-bridged diselenadiazolyl diradical 1,3-[(Se2N2C)C6H4(CN2Se2)] is reported. Crystals of this β-phase are monoclinic, space group P21/n, with a = 9.108 (6), b = 15.233 (13), c = 16.110 (5) Å, β = 103.37 (5)°, Z = 8. The crystal structure consists of chain-like arrays of discrete dimers (4 per unit cell), although one intradimer Se-Se linkage is notably longer (3.411 Å) than the other three (3.125, 3.196, 3.204 Å). The dimer units lie in chains that are linked by a complex three-dimensional array of Se-Se contacts. Variable-temperature single-crystal conductivity measurements on this phase indicate a band gap of 0.77 eV. Consistent with the conductivity measurements, extended Hückel band structure calculations suggest a relatively isotropic electronic structure.

The preparation and solid-state characterization of the 1,3-phenylene-bridged bis(dithiadiazolyl) and bis(diselenadiazolyl) diradicals 1,3-[(E2N2C)C6H4(CN2E2)] (E = S, Se) are reported. The isomorphous crystals of 1,3-[(E2N2C)C6H4(CN2E2)] so obtained are tetragonal, space group I41/a. Stacks of diradical molecules, linked vertically in a zigzag fashion through alternaie ends by long E- - -E contacts (mean 3.140/3.284 Å, for E = S/Se), are arranged in pinwheellike clusters about the 41 and ¯4 axes, producing complex patterns of interstack E- - -E contacts. Both compounds show the presence of spin defects in the lattice, and there is a very large enhancement in the paramagnetism of the sulfur compound at high temperatures. The selenium compound is a semiconductor, with a room temperature conductivity of 2 × 10-4 S cm-1. Solid-state NMR experiments find enhanced relaxation times, which have their origin in the presence of a mobile paramagnetic defect. Extended Hückel band structure calculations show the materials to be semiconductors, with band gaps of about 1.0/0.8 eV for E = S/Se. Although the compounds adopt a columnar structure, the calculations indicate significant interactions between the stacks and the materials exhibit well-developed three dimensionality. The enhanced paramagnetism in the sulfur compound is attributed to the presence of thermally generated phase kinks in the lattice, whereas the selenium compound is classified as an intrinsic semiconductor.

The radical units Se 2 N 2 CMe dimerize with long Se...Se distances of 3.159(3) and 3.187(3) A to give the title compound, C 4 H 6 N 4 Se 4 . There are two crystallographically independent dimers in the unit cell. The dimers adopt a twisted conformation with parallel ring planes. One ring is rotated on the axis between ring centers by approximately 90° from the eclipsed position to give Se-Se-Se-Se torsion angles of 86.81(15) and 88.95 (17)°. Se-Se bond lengths within the radicals vary from 2.306 (3) to 2.330 (3) A.

The title compound, [Cu(C 10 H 14 N 4 O 2 P) 2 ], consists of pairs of bis(dimethylpyrazolyl)phosphinato groups coordinated to copper(II) atoms sitting on inversion centers. The compound has Cu-N bond distances of 2.009 (4) and 2.010 (4) A and an N-Cu-N angle of 89.27 (13)° . The phosphinato O atoms weakly coordinate the copper ions with bond distances of 2.490 (3) A.

The title compound [Ru(C 5 H 5 )(C 2 H 5 NS)(C 18 H 15 P) 2 ]BF 4 crystallizes in the space group P2 1 /c. The Ru atom has pseudotetrahedral coordination geometry formed by the cyclopentadienyl centroid, the two PPh 3 ligands and the S atom of the neutral thioacetamide molecule. The Ru-S and C=S distances are 2.3820 (13) and 1.671 (5) A, respectively, and the Ru-S=C angle is 116.3 (2) o . The Ru atom is at a distance of 0.405 (9) A from the plane formed by the atoms of the thioacetamide group

[reaction: see text] A series of aromatic enynes containing steric buttressing elements were prepared and evaluated in the NMO-mediated Pauson-Khand cyclization. O-Allyl systems led to the expected angularly fused products, whereas the O-butenyl and O-pentenyl derivatives afforded the unprecedented bridge systems.

[Fe(CO) 4 (SO 2 )(C 5 H 5 ) 2 ]•H 2 O cristallise dans P2 1 /n avec a=10,884, b=12,424, c=12,658 A, β=103,35 o , Z=4; affinement jusqu'a R=0,0355. Les liaisons hydrogene entre l'eau et SO 2 lient les complexes entre eux. L'eau provoque la cristallisation du complexe dans usne conformation trans, en opposition a la forme gauche du materiau anhydre

C 18 H 14 Mn 2 O 6 Si cristalline dans P1 avec a=7,649, b=11,119 et c=12,203 A, α=98,39, β=104,68 et γ=96,29 o , Z=2; affinement jusqu'a R=0,039. Les deux cycles forment des angles diedres de 89,5 et 144,0 o avec le plan central et une unite Mn(CO) 3 est liee η 5 a chaque cycle

C 8 H 4 N 4 Se 2 2+ •2SbF 6 − •3C 7 H 5 N cristallise dans P1 avec a=6,829, b=13,981, c=21,320 A, α=72,26, β=89,03, γ=88,78 o , Z=2; affinement jusqu'a R=0,049. La maille cristalline contient quatre anions, six molecules de solvant et deux cations situes sur les centres d'inversion cristallographiques

[Rh(C 13 H 23 ) {(PCC 6 H 5 ) 3 } 2 ]•0,5 C 6 H 6 cristallise dans P1 avec a=12,260, b=13,05, c=15,91 A, α=71,30, β=76,24, γ=67,71 o , τ=2; affinement jusqu'a R=0,043. Les atomes du cycle a 13 chai←nons sont dans une configuration trans. Les distances des 3 atomes de ce cycle lies au metal sont de 2,120; 2,180; 2,231 A, et les angles formes par ces atomes sont de 123,9 et 125,7 o

C 24 H 20 ClN 3 P 2 Se cristallise dans P1 avec a=9,759, b=11,046, c=13,332 A, α=65,50, β=64,89, γ=74,96 o , Z=2; affinement jusqu'a R=0,036. Dans le cycle a 5 chai←nons, l'un des liens entre P et N est presque plan (a 0,053 A pres), tandis que l'atome Se soit de ce plan de 0,499 A du cote du chlore. Les longueurs des liaisons de la sequence Se−N−P−N sont en moyenne de 1,730; 1,637 et 1,584 A. Les angles des liaisons du cycle autour des atomes Se et P sont respectivement de 111,5 o et 117,8 o

Cristallisation dans C2/c avec a=11,578, b=22,122 et c=13,672 A, β=110,31 o , Z=4; affinement jusqu'a R=0,046. Le cation est localise sur un centre cristallographique de symetrie et deux anions SbF 6 − independants sont localises chacun sur un axe de rotation d'ordre 2. L'un des anions est desordonne

C 16 H 22 S 2 cristallise dans P2 1 /n avec a=8,851, b=15,398 et c=11,590 A, Z=4; affinement jusqu'a R=0,036. Presence de quatre contacts intramoleculaires entre les atomes H et le cycle phenylene dans le domaine 2,53 a 2,68 A, contribuent au «benzene courbe» typique des paracyclophanes

The Ru atom of the title complex, [Ru(C10H8N2)2-(H2O)2](PF6)2, is located on a crystallographic inversion center; the bipyridine ligands are bowed [dihedral angle between C5N planes is 162.68 (12) degrees] due to the interligand steric interactions of the trans bipyridyl units. The Ru--O distance is 2.116 (2) A and the mean Ru--N distance is 2.074 (2) A.

Sublimation of 1,2,3,5-dithiadiazolyl in vacuo affords a triclinic phase of the dimer [HCN2S2]2. The crystals belong to the space group P¯1, a = 6.816(3), b = 13.940(2), c = 14.403(3) Å, α = 116.830(14), β = 98.64(3), γ = 99.18(3)°, FW = 212.4 (for [HCN2S2]2·[N2]0.08) Z = 6. The crystal structure consists of stacked dimers, with three dimers per asymmetric unit. Pairs of asymmetric units, related by an inversion center, generate a pinwheel motif consisting of six dimers. The columnar structure associated with these pinwheels forms close-packed sets of “molecular tubes”. Cosublimation of the radical in the presence of iodine in the mole ratio (HCN2S2:I = 5:1) yields an iodine-doped hexagonal phase of composition [HCN2S2]6[I]1.1. Crystals of this material belong to the space group P61, a = b = 14.132(16), c = 3.352(5) Å, FW = 128.20, Z = 6. The crystal structure consists of sixfold pinwheels in which the now evenly spaced HCN2S2 rings form a spiral about the 61 axis. The iodine atoms lie within the columnar cavity of the pinwheels in a disordered array wrapped tightly about the sixfold screw axis. The single-crystal conductivity of the doped material is 15 S cm-1 at room temperature. Raman spectroscopic and magnetic susceptibility measurements on the doped material are reported.

The 1:1 reaction of the heterocyclic radicals [PhCN2E2]∙ (E = S, Se) and iodine affords the mixed valence salts [PhCN2E2]3[I3], while reaction of PhCN2S2 with an excess of iodine affords the simple salt [PhCN2S2][I3]; the solid-state structures of these complexes have been determined by X-ray crystallography. Crystals of both of the mixed valence compounds belong to the triclinic space group P¯1; for E = S, a = 10.278(4), b = 11.508(2), c = 13.333(4) Å, α = 114.97(2), β = 99.21 (3), γ = 92.65(2)°, FW = 308.15, Z = 6; for E = Se, a = 10.368(6), b = 10.818(8), c = 13.421(8) Å, α = 80.64(5), β = 81.20(5), γ = 75.18(6)°, FW = 401.95, Z = 6. Crystals of the simple salt belong to the monoclinic space group P21/a; a = 7.366(4), b = 11.734(1), c = 15.166(2) Å, β = 95.92(3)°, FW = 1303.99(7), Z = 4. In each of the mixed valence compounds the molecular (asymmetric) unit consists of a trimeric [PhCN2E2]3+ cation and an associated triiodide anion. Within the cations the mean interannular E-E contacts are 3.181/3.377 Å (E = S/Se). The packing patterns of the two compounds show important differences. For E = S the crystal structure does not exhibit stacking of the trimeric molecular building blocks, but for E = Se the trimer units form dovetailed stacks in which consecutive layers are oriented in a trans-antipodal fashion. This arrangement introduces close interannular contacts between the blocks along the stack, as well as close lateral contacts. The asymmetric unit of [PhCN2S2][I3] consists of a single PhCN2S2+ cation and an associated triiodide anion; there are no unusual stacking features. The magnetic and conductivity properties of [PhCN2Se2]3[I3] are reported, and the results discussed in the light of extended Hückel band structure calculations.

MOST molecular conductors rely on charge transfer to create carriers. For example, the ET salts1 are hole-doped whereas the C60 salts2 are electron-doped. Neutral radical species in which bands are formed by π-orbital overlap would be expected to have half-filled bands and thus to be conducting3, but no such metals have yet been reported. Here we report the synthesis and characterization of a molecular conductor which combines both of these approaches: energy bands are formed from one-dimensional stacks of neutral π-radicals, and the material is rendered conducting by electron transfer from the conduction band following doping with an acceptor. The radical species is the l,4-phenylene-bis(dithiadiazolyl) diradical 1,4-[(S2N2C)C6H4(CN2S2)] (2 in Fig. 1), reaction of which with iodine vapour leads to crystals of [2][I]. At low temperatures this compound is essentially a diamagnetic insulator, but above 200 K the conductivity and magnetic susceptibility increase markedly, and at room temperature the conductivity reaches l00 S cm−1, which is comparable to that shown by conventional molecular charge-transfer salts.

The preparation and solid-state characterization of the bifunctional radicals [4,4’-(5-cyanobenzene)-1,3-bis(1,2,3,5-dithiadiazolyl)] and [4,4’-(5-cyanobenzene)-1,3-bis( 1,2,3,5-diselenadiazolyl)] [5-CN-1,3-C6H3(CN2E2)2] (E = S, Se) are described. The crystals of the two title compounds are isomorphous and belong to the monoclinic space group P21/c, with (for E = S) a = 7.00(2), b = 30.050(6), c = 10.713(8) A, β = 104.80(10)°, V = 2179(6) A3, Z = 8 and (for E = Se) a = 7.124(4), b = 30.50(2), c = 10.874(2) A, β = 105.46(3)°, V = 2277(2) A3, Z = 8. The crystal structures consist of stacks of diradicals running parallel to x; radical dimerization up and down the stack generates a zigzag arrangement, as seen in the related 1,3-phenylene structures. Along the stacking axis the mean intradimer E-E contacts are 3.12 (E = S) and 3.23 A (E = Se), while the mean interdimer E- - -E distances are 3.89 (E = S) and 3.91 A (E = Se). Magnetic and conductivity data are presented and discussed in light of extended Huckel band structure calculations.

The preparation and solid-state characterization of the trifunctional radical 1,3,5-benzenetris(1,2,3,5-dithiadiazolyl) [4,4’,4”-(1,3,5-benzenetriyl)tris[1,2,3,5-dithiadiazolyl], 1,3,5-C6H3(CN2S2)3] are described. The crystals belong to the monoclinic space group P21/c, with a = 6.927 (2), b = 19.798 (3), c = 19.393 (3), and β = 99.80 (2) A3. The crystal structure consists of stacks of triradicals running parallel to x. Each radical center associates with a neighboring radical, generating alternating long (mean 3.832 A) and short (mean 3.117 A) interradical S···S contacts along the stack; only two of the three crystallographically distinct bond alternation waves so generated are in-phase. The packing of triradical stacks produces an extensive network of close interstack S···S contacts. The compound is diamagnetic at room temperature, but paramagnetic defects begin to appear near 450 K. The room-temperature single-crystal conductivity is near 10-7 S cm-1. Extended Huckel band structure calculations reveal a band gap of 0.8 eV.

The synthesis and crystal structure of 2,5-diamino-3,6-dichloropyrazine, C4H4Cl2N4, are described. The centrosymmetric molecule has an exocyclic C—N distance of 1.362 (3) A, and a nearly planar amine group [the angles at N sum to 351 (2)°]. Within the crystal, the molecules form a ribbon through two centrosymmetric pairs of N—H⋯N hydrogen-bond interactions, where the N⋯N distance is 3.110 (3) A.

A crystallographic twofold rotation axis passes through the C-C bond joining the imidazole rings of the title compound, C10H10N4O2. The molecule crystallizes in a cis disposition. The planar acetyl group is twisted by 5.0 (3)° with respect to the imidazole ring and the two imidazole rings are tilted by 60.53 (5)° in relation to one another.

The title molecules, C 6 H 4 N 6 O 4 .2C 3 H 7 NO, lie on a center of inversion. One N atom of the ring is hydrogen bonded to the O atom of the dimethylformamide (DMF) solvate molecule [N-H...O = 2.699 (4) A]. The nitro group is tilted by 4.11 (18)° with respect to the imidazole ring.

Ru(HSO3)2(NH3)4), Mr=331.3, mono- clinic, P21/c, a = 6.2019 (15), b = 7.0213 (11), c = 11.761 (2)A, fl= 115.30(2) °, V= 463.0 (3) A 3, Z= 2, Dx = 2-38 g cm -3, A(Mo Kte) = 0.71073 A,, /z = 21-0 cm- 1, F(000) = 332, T = 293 K, R = 0.019 for 1179 reflections with Fo 2 > 3o'(Fo2). The complex lies on an inversion center with Ru-N distances of 2.141 (2) A, and a Ru-S distance of 2-2785 (5) A.. All of the H atoms are linked to O atoms of neighboring hydrogensulfite ligands in an extensive network of H bonds. Experimental. The title complex (I) was obtained by the procedure described by Vogt, Katz & Wiberley (1965). Colorless crystals were obtained by slow cooling of the reaction mixture. Data crystal was 0.12 x 0-20 x 0-32 mm and was mounted with epoxy on a glass fiber. Intensities measured with an Enraf- Nonius CAD-4 diffractometer using o~--20 scans of 4-16 ° min-~ in 0. Unit cell determined from least- squares analysis of angle data for 25 reflections with 17 < 20 < 22 °. Analytical absorption correction varied from 0-79 to 1.00. Data collected to (sin0)/A =0.68A.-', 0_

K[RuCl 4 (C 10 H 8 N 2 )] cristallise dans Pbcn avec a=14,382, b=13,980 et c=7,491 A, Z=4; affinement jusqu'a R=0,051. L'anion [Ru(bpy)Cl 4 ] − est sur un axe cristallographique d'ordre 2. Les cycles organiques des anions voisins se recouvrent avec des espacements entre les plans 3,27 et 3,36 A

Preparation du complexe trans-[Ru(phen) 2 (OH 2 ) 2 ]PF 6 par photolyse du cis en solution aqueuse de HPF 6 . Par substitution thermique de coordinats, formation de trans-[Ru(phen) 2 (CH 3 CN)(OH 2 )](PF 6 ) 2 , trans-[Ru(phen) 2 (CH 3 CN) 2 ](PF 6 ) 2 et trans-[Ru(phen) 2 (py) 2 ](PF 6 ) 2 . Isomerisation des trans en cis. Structure cristalline

An expedient synthesis of previously unknown (1 Z , 3 Z )-1, 4-dibromobutadiene is reported. When this dibromide is treated with s- or t-butyllithium, (1 Z , 3 Z )-1-bromo-4-lithio-butadiene is generated. Treatment of the dibromide with four equivalents of t-butyllithium gives (1 Z , 3 Z )-dilithiobutadiene. Reaction of (1 Z , 3 Z )-1-bromo-4-lithiobutadiene with (η 5 -C 5 H 5 )Fe(CO) 2 I gives (1 Z , 3 Z )-(η 5 -C 5 H 5 )Fe-(CO) 2 CH=CHCH=CHBr. X-ray crystallographic analysis of this latter compound establishes the geometry about the bromobutadiene ligand.

Cristallisation dans le groupe P2 1 /c avec a=9,216, b=14,318 et c=10,229 A, β=104,57°, Z=4. Affinement jusqu'a R=0,037. La molecule est formee d'une unite norbornenyl avec deux groupes S 3 N attaches de facon exo aux positions 2,3. Effets des differents substituants sur l'energie de transition π*→π* des derives X-S 3 N

The cation trans -[Ru(bpy) 2 (PPh 3 ) 2 ] 2+ and trans -[Ru(Me 2 bpy 2 ) 2 (py) 2 ] 2+ both contain bipyridine ligands which are distorted because of the crowding of the two chelate units. The hexafluorophosphate salt of the first cation crystallizers in space group P2 1 /n, with a = 11.630(1), b = 20.245(2), c = 11.299(1)A, &#x03B2 = 103.99(1)°, and Z = 2. R = 0.047 for 2396 observed reflections. The hexafluorophosphate salt of the second cation crystallizers in space group C2/m, with a = 18.392(2), b = 11.265(1), c = 13.383(1)A, &#x03B2 = 139.42(2)°, and Z = 2. R = 0.047 for 1403 observed reflections. The Ru of the first cation lies on an inversion center and the Ru of the second cation lies on a special position of 2/m symmetry. The distortions of a number of bipyridine complexes with the trans geometry are analyzed and found to fall into two categories, bowed or twisted. The two complexes of this report were found to have a bowed conformation.