Infrared and Raman spectroscopic evidence of ground state charge densities at TCNQ sites in crystalline Cs2 (TCNQ)3

The reported Raman spectrum of the Rb TCNQ salt allows, for the first time, examination of all the vibrational features of the TCNQ ^? radical anion. The knowledge of the TCNQ fundamental frequencies as well as of those for neutral TCNQ makes it possible to interpret the infrared and Raman spectra of Cs₂ (TCNQ)₃ and to conclude that in this salt both neutral and negatively charged TCNQ units are present in the crystal. The result is a first fruitful application of vibrational spectroscopy to the study of complex TCNQ salts, opening the way to an extensive investigation of TCNQ semiconducting salts.     

The luminescence of uranime-activated yttrium tungstate (Y2WO6)

The luminescence of uranium in Y₂WO₆ can be excited with long wavelength ultraviolet radiation at temperatures below room temperature. The emission consists of a fairly narrow band in the orange part of the spectrum. Its characteristics are comparable with the luminescence of uranium in MgWO₄ and the scheelites MWO₄ (M = Ca, Sr, Ba). It is possible to relate the thermal quenching temperature of the luminescence to spectral data. Energy transfer from the tungstate group to the uranate group is observed, but its efficiency is not very high compared with other systems.     

Internally coordinated organozinc-transition metal compounds. Crystal structure of (CH3)2N(CH2)3ZnW(ν-C5H5)(CO)3

The stabilities of simple and internally coordinated organozinc-transition metal compounds towards disproportionation have been investigated by the microwave titration technique. Simple alkyl- and aryl-derivatives disproportionate to such an extent as to preclude isolation. Internal coordination was found to stabilize the asymmetric compounds, and several derivatives containing the dimethylaminopropyl group were isolated. The crystal structure of one of them, Me₂N(CH₂)₃-ZnW(Cp)(CO)₃, was determined by a single-crystal X-ray study. The crystals are orthorhombic, space group P2₁2₁2₁, with four molecular units in a cell with parameters a 8.406(1), b 12.179(2) and c 16.642(2) Å. The structure was solved by standard Patterson and Fourier techniques. The refinement, with anisotropic temperature factors for the two heavy atoms, converged at R_F = 0.092 (R_wF = 0.089) for 1536 observed reflections with I>2.5σ(I). The molecule consists of a central tungsten atom, surrounded in a tetragonal pyramidal fashion by a cyclopentadienyl group in the apical position and three carbon monoxyde molecules and a zinc atom occupying the basal positions. The zinc atom is three-coordinate, being surrounded by the tungsten atom and the chelating dimethylaminopropyl group; there is, however, a short intermolecular contact between zinc and a carbonyl oxygen atom at 2.61(3) Å.     

Preparation,properties and x-ray crystal structure of a complex of bis(triphenylphosphoranylidene)ammonium iodide with 7,7,8,8-tetracyano-P-quinodimethane: (PPN)2(TCNQ)3(CH3CN)2

Bis(triphenylphosphoranylidene)ammonium iodide (PPN⁺I^?) forms a 2:3 complex with TCNQ [(PPN)₂(TCNQ)₃(CH₃CN)₂] that provides an example of a TCNQ complex containing acetonitrile in the crystal lattice; the material is a semi-conductor with trimerised TCNQ stacks.     

Crystal structures of phosphomolybdyl salts: Pb(MoO2)2(PO4)2 and Ba(MoO2)2(PO4)2

Crystal structures of Pb(MoO₂)₂(PO₄)₂ and Ba(MoO₂)₂(PO₄)₂ were determined. Both compounds contain the molybdyl group MoO₂. The monoclinic unit-cell parameters are a = 6.353(7), b = 12.289(4), c = 11.800 Å, β = 92°56(6), and Z = 4 for the lead salt and a = 6.383(8), b = 7.142(7), c = 9.953(8) Å, β = 95°46(8), and Z = 2 for the barium salt. $\text{P2}{}_1\text{c}$ is the common space group. The R values are respectively R = 0.027 and R = 0.031 for 1964 and 1714 independent reflections. The frameworks built up by a three-dimensional network of monophosphate PO₄ and molybdyl MoO₂ groups are similar, characterized mainly by corner-sharing PO₄ and MoO₆ polyhedra. Two oxygen atoms of each MoO₆ group are bonded to the molybdenum atom only as in other molybdyl salts.     

Anisotropy of the infrared reflectivity spectra of the salt TeEA (TCNQ)2

Single crystal reflectivity spectra of the salt TeEA (TCNQ)₂ were measured in the frequency range 50 – 13500 cm^?1 for three well-shaped crystal faces g(100), f(010), and h(001). The spectra of the faces g(100) and f(010) are practically the same but that of the face h(001) shows distinct differences. This is evidence of anisotropy of the optical properties of the TCNQ anion-radical dimer. The spectra can be interpreted on the basis of the theory of an isolated TCNQ dimer with one radical electron on it.     

1,2-Hydrogen abstraction: the characterization of [Li(CH3)2N(CH2)2N(CH3)2]2 [C12H8]. A dilithium complex obtained by the 1,2 deprotonation of acenaphthylene

The reaction of n-butyllithium chelated to N,N,N′,N′-tetramethylethylenediamine (TMEDA) with acenaphthene results in 1,2-hydrogen abstraction to give the dilithio complex of acenaphthylene, [Li(CH₃)₂N(CH₂)₂N(CH₃)₂]₂[C₁₂H₈]. This compound was isolated as a crystalline product and characterized by single crystal X-ray crystallography. [Li(CH₃)₂N(CH₂)₂N(CH₃)₂]₂[C₁₂H₈] crystallizes with a unit cell of a = 23.164(10), b = 25.609(10) and c = 8.495(6) Å in the orthorhombice space group Fdd2. The calculated density is 1.04 g cm^?3 for 8 molecules per unit cell. The observed density is 1.03(4) g cm^?3. 1412 unique reflections were measured on a full circle X-ray diffractometer. The light atom, acentric structure was solved by the symbolic addition technique and refined by full matrix least squares to R₁ = 0.058 and R₂ = 0.056.The acenaphthylene fragment is nearly planar. The effect of charge transfer is evidenced in the short C(3)C(4) bond distance of 1.30(3) Å and the lengthening of the C(1)C(2) bond length from the localized olefinic bond distance of 1.34 to 1.42(2) Å. The two LiTMEDA fragments are coordinated to both sides of the five membered carbon atom ring of the acenaphthylene group.     

Two-photon spectroscopy in the gas phase: 1B2u ← 1Ag transition of p-difluorobenzene

The two-photon excitation spectrum ¹B_2u ← ¹A_g of p-difluorobenzene in the gas phase is presented and analysed. The normal absorption is electric dipole allowed and shows no vibronic coupling, but the two-photon absorption is electric dipole forbidden and displays rich vibronic structure. Eight vibronic origins are assigned to their excited state fundamentals by analysis of the hot bands and by analogy with benzene. The only previously unassigned ground state frequency, an a_u mode, is active in the spectrum and is accordingly assigned. The sequences and the abundant Fermi resonances accompanying absorption are also partially assigned.     

Experimental investigation of excited state electron transfer reactions between some bicyclic molecules and tetracyanoquinodimethane (TCNQ)

Investigations on photoinduced electron transfer (ET) reactions between excited (ground) bicyclic electron donors 5,6,7,8-tetrahydro-2-naphthol (TH2N), 2-methoxy-5,6,7,8-tetrahydro naphthalene (2MTHN) and ground state (excited) acceptor tetracyanoquinodimethane (TCNQ) in fluid solutions of different polarity at the ambient temperature (300 K) by electronic absorption, steady state fluorescence and time-resolved spectroscopic methods in the time domain of nanosecond order have been carried out. It is suggested that in highly polar solvent acetonitrile (ACN), a loosely-structured transient geminate ion-pair complex (GIP) in the excited singlet state (S₁) is formed due to the ET encounter between the present donor TH2N or 2MTHN and TCNQ and this GIP complex rapidly dissociates into stable excited radical ions, as evidenced from steady state spectra. In polar DMF solvents, TCNQ exhibits an electronic absorption band of its anion without the presence of donor molecules. Both steady state and time-resolved data indicate that ET reactions between the present donors and acceptor TCNQ are largely impeded in the less polar solvent tetrahydrofuran (THF). In the highly polar solvent ACN, ET reactions between the donors and acceptor TCNQ have been suggested to be of adiabatic or intermediate between adiabatic and non-adiabatic types, from the observation of radical ion species in the electronic excited state. For some bicyclic donors and TCNQ acceptor systems, large negative ΔG, which is a measure of the gap between locally excited and radical ion-pair states, shows reaction occurs in highly exothermic regions. Further observations of −ΔG>λ, nuclear reorganization energy parameters and the decrement of ET rate (k_ET) with increasing exothermicity (more negative ΔG values) suggest the ET reaction for the bicyclic donor—TCNQ acceptor systems studied in the present investigation might occur in the Marcus inverted region. The possibility of building up efficient photoconducting materials with the present donor acceptor systems is suggested.     

Dual luminescences in [W(Cp)(CO)3]2 and [Mo(Cp)(CO)3]2

Cyclohexane solutions of [W(Cp)(CO)₃]₂ and [Mo(Cp)(CO)₃]₂ exhibit weak bimodal emission spectra when excited With 354 nm picosecond pulses, but do not luminesce when pumped at 530 nm. Picosecond lifetimes characterize the short-wavelength, emission bands, which may originate from metal-cyclopentadienyl CT excited states.     

过渡金属吡啶配离子的TCNQ电荷转移盐的合成和物理性质

合成了通式为[M(Py)_m][TCNQ]_n(M=Mn,m＝4;M＝Co,Ni,Cu,m＝2;TCNQ＝7,7,8,8-四氰基对苯醌二甲烷,n＝2,3)的8个过渡金属吡啶配离子的TCNQ电荷转移盐,通过元素分析、红外光谱、顺磁共振谱、光电子能谱、磁化率和电导率对这些电荷转移盐进行了表征,结果表明,在这些电荷转移盐分子中存在TCNQ^-和TCNQ⁰,且TCNQ^-与TCNQ⁰相互作用形成结构单元[TCNQ]_n^2-(n＝2,3),各个结构单元沿一维方向堆积形成分子柱,部分电荷从[TCNQ]_n^2-向[M(Py)_m]²⁺转移,导致化合物中的金属表现为混合价态.其中3个电荷转移盐具有良好的导电性.     

Matrix Isolation and IR spectroscopy of stannylenes (CH3)2Sn and (CD3)2Sn

Free stannylenes Me₂Sn and (CD₃)₂Sn, generated thermally from the cyclic hexamers or by microwave discharge from Me₂SnH₂, are isolated by Argon matrix technique. All IR bands could be attributed to the important molecular vibrations by normal coordinate analysis. As shown by ab initio SCF calculations, Me₂Sn has a singlet groud state, the angle CSnC is 95.3°, the CSn bond length is 2.203 Å.     

Substitution in barium-fluoride apatite: The crystal structures of Ba10(PO4)6F2, Ba6La2Na2(PO4)6F2 and Ba4Nd3Na3(PO4)6F2

The crystal structures of the apatites Ba₁₀(PO₄)₆F₂(I), Ba₆La₂Na₂(PO₄)₆F₂(II) and Ba₄Nd₃Na₃(PO₄)₆F₂ (III) have been determined by single-crystal X-ray diffraction. All three compounds crystallize in a hexagonal apatite-like structure. The unit cells and space groups are: I, a = 10.153(2), c = 7.733(1)Å, $\text{P6}{}_3\text{m}\text{; a = 9.9392(4), c = 7.4419(5)}$Å, $\text{P}\text{6}$; III, a = 9.786(2), c = 7.281(1)Å, $\text{P}\text{3}$. The structures were refined by normal full-matrix crystallographic least squares techniques. The final values of the refinement indicators R_w and R are: I, R_w = 0.026, R = 0.027, 613 observed reflections; II, R_w = 0.081, R = 0.074, 579 observed reflections; III, R_w = 0.062, R = 0.044, 1262 observed reflections.In I, the Ba(1) atoms located in columns on threefold axes, are coordinated to nine oxygen atoms; the Ba(2) sites form triangles about the F site and are coordinated to six oxygen atoms and one fluoride ion. The fluoride ions are statistically displaced ～0.25 Å from the Ba(2) triangles. This displacement of the F ions is analogous to the displacement of OH ion in Ca₁₀(PO₄)₆(OH)₂.The structures of II and III contain disordered cations. In II there is disorder between La and Na in the column cation sites as well as triangle sites. In III, Nd and Na ions are ordered in the column sites, but there is disorder among Ba and the remaining Nd and Na ions in the triangle sites to give an average site population of $\text{2}\text{3}\text{Ba}\text{,}\text{1}\text{6}\text{Nd}\text{,}\text{1}\text{6}\text{Na}$. The coordination of the rare earth ions and Na ions in the ordered column sites are nine and six oxygens, respectively, in accord with the greater charge of the rare earth ions as compared with Na. The F ions in both II and III suffer from considerable disorder in position, and their locations are not precisely known.     

On the molecular structure of (CH3)2NSO2N(CH3)2 as studied by gas electron diffraction

The following bond lengths and bond angles have been deduced from a vapour phase electron diffraction study of (CH₃)₂NSO₂N(CH₃)₂: r(C-H) 1.114 ± 0.005 Å, r(S-O) 1.432 ± 0.010 Å, r(N-C) 1.475 ± 0.013 Å, r(S-N) 1.651 ± 0.003 Å, ∠N-C-H 109.3 ± 2.0°, ∠C-N-C 118.0 ± 302°, ∠S-N-C 115.2 ± 1.1°, ∠N-S-N 110.5±1.3° and ∠O-S-O 114.7±2.5°. The sulphur bond configuration and the prevailing conformation, which was identical to that in the crystal, are discussed in relation to analogous sulphide and sulphoxide derivatives.     

Synthesis and crystallographic characterization of a dicyclopentadienylvanadium alkynide complex: (C5H5)2VCCC(CH3)3

(C₅H₅)₂VCl reacts with LiCCC(CH₃)₃ to form (C₅H₅)₂VCCC(CH₃)₃ which was characterized by spectroscopic, analytical, and crystallographic methods. The complex crystallizes from pentane at 0°C as a monomer in the orthorhombic space group Pnma with four molecules in a unit cell of dimensions a 9.075(3), b 9.807(3), c 16.444(5) Å. Full-matrix least-squares refinement based upon 1300 nonzero intensity data converged to a final conventional R factor of 0.060. The molecule has a mean VC₅H₅-ring centroid distance of 1.941 Å with 146.6° ring centroid-V-ring centroid angle. The vanadium alkynide carbon distance is 2.075(5) Å.     

A dichromium(II) compound with an elongated metal-metal bond: Cr2(oxindolate)4(oxindole)2

The title compound has been prepared by reaction of (C₅H₅)₂Cr with oxindole (indole with CO in place of CH₂ at the 2-position). Red single crystals belong to space group P2₁/c with a = 10.107(4) Å, b = 22.496(7) Å, c = 9.210(3) Å, β = 93.26(3)°, V = 2091(2), and Z = 2. The centrosymmetric molecule has a CrCr distance of 2.495(4) Å. The mean CrO and CrN distances for the bonds to bridging oxindolate anions are 2.024(7) and 2.065(8) Å, respectively. There is an oxindole molecule bound at each end with a CrO axial bond of length 2.341(8) Å and a hydrogen bond from the oxindole NH group to an equatorial oxygen atom of length 2.83(1) Å. The significance of this compound with respect to CrCr bonding is discussed.     

The preparation and characterization of CdIr(OH)6 and ZnIr(OH)6

CdIr(OH)₆ and ZnIr(OH)₆ were isolated and characterized in the process of synthesizing new ternary oxides of the platinum-group metals by means of thermal decomposition of hydroxide intermediates. Both compounds crystallize with an ordered ReO₃-type structure. CdIr(OH)₆ is tetragonal with a = 7.86 Å and c = 7.91 Å. It is a magnetically dilute insulator. ZnIr(OH)₆ is cubic with a = 7.64 Å. It is an insulator with anomalous magnetic behavior. The cadmium and zinc iridium hexahydroxides decompose at 180 and 170°C, respectively.     

Near infrared electronic spectrum of TCNQ mono-valent anion

The high resolution near infrared electronic spectrum of TCNQ anion dissolved in 2-methyltetrahydrofuran glass at 77 K has been determined. The absorption bands are interpreted as simple progressions of two molecular vibrations in a single electronic excited state with ν₀₀ = 11661 cm^?1. The molecular vibrations (ω′₁ = 1264 ± 3 cm^?1, ω′₂ = 335 ± 3 cm^?1) of the vibrational progression agree well with observed Raman active transitions. The experimental data do not require the presence of two electronic transitions in the 1.3 to 2.1 eV region, contrary to what had been assumed previously on the basis of less well resolved room temperature spectra.     

Syntheses and structural studies on two cycloruthenapentadienyl complexes: [(CO)3RuC4(CH2OH)4]Ru(CO)3·H2O and [(CO)3RuC4(CH2CH2OH)2(C2H5)2]Ru(CO)3

Syntheses and single-crystal X-ray diffraction studies have been completed on two cycloruthenapentadienyl (CO)₆Ru₂L₂ derivatives, with L = CH₂OHC = CCH₂OH and C₂H₅C=CCH₂CH₂OH respectively. Crystal data are as follows: for [(CO)₃RuC₄(CH₂OH)₄]Ru(CO)₃·H₂O, P2₁/c, a 13.72(1), b 9.501(4), c 14.86(1) Å, β 101.10(6)°, R_w = 0.052 for 1911 reflections; for [(CO)₃RuC₄(CH₂CH₂OH)₂(C₂H₅)₂]Ru(CO)₃, P2₁/c, a 9.191(3), b 16.732(4), c 14.903(3) Å, β 113.61(4)°, R_w = 0.042 for 2865 reflections. Both compounds are built up from binuclear units, each unit being regarded as a Ru(CO)₃ fragment π-bonded to a cycloruthenapentadienyl ring. The molecular parameters are compared with those of known cyclometallapentadienyl complexes of transition metals. The presence of a semi-bridging CO group is discussed.     

Structural studies of complexes containing the coordinated methyldisulphido ligand: The crystal structure of [Os (η2-S2CH3) (CO)2 (P (C6H5)3)2] ClO4·12 C6H6.

Crystal and molecular structures of the title compound have been determined from a three-dimentional X-ray analysis usinq diffractometer data. The crystals are triclinic, space group P$\text{1}$, with Z = 2 in a unit cell of dimensions a = 14.23(1), b = 17.30(1), c = 10.44(1) Å, α = 102.1(2), β = 102.7(2), γ = 105.5(2)°. Full matrix least squares refinement has given a final R-factor of 0.060 for 4628 reflections for which I > 3σ(I).The crystal structure consist of discrete cations and anions, together with benzene molecules of crystallisation which are situated about the crystallographic centres of symmetry and serve a purely space-filling role. In the cation coordination about the osmium atom is that of a distorted octahedron, comprising the two triphenylphosphine groups (mutually trans), the two carbonyl groups (mutually cis) and the dihapto S₂Me group. The Os-P distances of 2.420 and 2.419(3) Å are normal. The S₂Me group is nearly symmetrically coordinated with Os-S(l) 2.426(4)Å and Os-S(3) 2.442(4) Å. Other bonds and angles in this ligand are S(1)-S(2) 2.022(7) Å, S(1)-CH₂ 1.81(2) Å, and S(2)-S(1)-CH₃ 105.4(6)°. The observed geometry is similar to that in [Ir(S₂) (Ph₂PCH₂CH₂PPh₂)₂Cl.Ch₃CN.