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As a part of our study of the syntheses of aryl amides, the crystal structures of two benzamides were determined from single-crystal X-ray data at 173 K. Both crystal structures contain mol-ecular units as asymmetric units with no solvent in the unit cells. Crystal structure I

Introduction Recent interest in carbon dioxide sequestration has prompted much research into ways of forming compounds from CO2 (1). One possible route for this process is reaction of CO2 with carbenes, which can be formed from the reduction of imidazolium cations (2). This paper reports recent results in this regard, carried out in a room-temperature ionic liquid. Experimental All electrochemical experiments were carried out in a Vacuum Atmospheres glovebox. Cyclic voltammograms were obtained on a PAR 283 potentiostat using PowerSuite software. Potentials are reported with respect to an Ag/AgCl reference electrode. X-Ray diffraction structure determinations were run on a Bruker AXS Kappa APEX-II. 1-Ethyl-3-methylimidazolium tetrafluoroborate (EMI BF4 ) and 1-butyl-1-methylpyrrolidinium trifluoromethylsulfonate (BMPY TfO) were prepared by literature methods (3, 4). Results and Discussion The electrochemical properties of EMI BF4 were investigated in the room-temperature ionic liquid BMPY TfO. The EMI cation undergoes reduction at -2.2 V vs Ag/AgCl, followed by an oxidation process at -0.40 V on the reverse sweep. Introduction of CO2 into the solution results in a rather large increase in the reduction process at -0.40 V, suggesting that the EMI+ reduction product can interact with the added CO2 in a catalytic process. For comparison, CO2 reduction by itself in BMPY TfO occurs at -2.8V, so that the observed current increase at -0.40 V for the EMI+ / CO2 combination is not due to direct reduction of CO2. In order to identify the reaction products from the EMI+ / CO2 interaction, voltammograms of the imidazolium – carboxylate adducts, 1,3-dimethylimidazolium-2-carboxylate and 1,3-dimethylimidazolium-4-carboxylate, were run. The adduct structures were confirmed by X-ray structure determinations. The reduction of these adducts occurs at -2.6 V and -2.4 V, respectively, with an oxidation process at -0.35 V on the return sweep. These results support the formation of CO2 adducts with the EMI+ reduction product, probably a carbene. References (1) “Electrochemical CO2 Reduction on Metal Electrodes,” Y. Hori, Modern Aspects of Electrochemistry, Number 42, edited by C. Vayenas et al., Springer, New York, (2008). (2) A. B. Bocarsly, Q. D. Gibson, A. J. Morris, R. P. L’Esperance, Z. M. Detweiler, P. S. Lakkaraju, E. L. Zeitler, and T. W. Shaw, ACS Catalysis, 2, 1684 (2012). (3) S. Park and R. J. Kazlauskas, J. Org. Chem. 66, 8395 (2001). (4) L. Crowhurst, N. L. Lancaster, J. M. P. Arlandis, and T. Welton, J. Am. Chem. Soc., 126, 11549 (2004).

Two series of Ru-II polypyridyl compounds with formulas [(bpy)(2)RuL](PF6)(2) and [(deeb)(2)RuL](PF6)(2), where bpy is 2,2-bipyridine, deeb is 4,4-diethylester-2,2-bpy, and L is one of several substituted 9-(1,3-dithiole-2-ylidene)-4,5-diazafluorene ligands, were studied as potential photosensitizers for TiO2. These compounds possess notably high extinction coefficients (40000M(-1)cm(-1) @470 nm) which are shown by time-dependent density functional theory (TD-DFT) calculations to result from overlapping metal-to-ligand charge transfer (MLCT) and ligand-localized transitions. Low-temperature absorption and photoluminescence measurements were suggestive of a short-lived MLCT excited state. When adsorbed onto TiO2 thin films, both the free ligands (L) and their corresponding [(deeb)(2)RuL](2+) complexes exhibited rapid excited-state electron injection into TiO2; in the case of the complexes, this was followed by rapid (k>10(8) s(-1)) hole transfer from Ru-III to the 1,3-dithiole ring of the L ligand. Observation of diffusion-limited reductive quenching of the [Ru(bpz)(3)](2+)* (bpz is 2,2-bipyrazine) excited state by the L ligands in solution supported the occurrence of intramolecular hole transfer following electron injection by the TiO2-anchored complexes.

During the time that students spend studying the fundamentals of quantum chemistry and chemical bonding, there are few laboratory experiments that can be performed to reinforce their learning. A simple experiment has been developed to afford students the opportunity to practice writing electron configurations for atoms and ions while relating the configurations to observed diamagnetic and paramagnetic properties of different chemical compounds. Assessment of common exam questions in our fall semester course indicates an improvement in student performance in correctly identifying electron configurations.

The synthesis and characterization of the copper(II) complexes of a series of tetradentate, pentadentate and hexadentate aminopyridine ligands that contain ethylenediamine and/or propylenediamine groups are described. The ligands include: 1,12-bis(2-pyridyl)-2,5,8,11-tetraazadodecane, TRIEN-pyr; 1,13-bis(2-pyridyl)-2,5,9,12-tetraazatridecane, DIEN-PN-pyr; 1,14-bis(2-pyridyl)-2,6,9,13-tetraazatetradecane, DIPN-EN-pyr; 1,15-bis(2-pyridyl)-2,6,l0,14-tetraazapentadecane, TRIPN-pyr; 1,9-bis(2-pyridyl)-2,5,8-triazanonane, DIEN-pyr; 1,11-bis(2-pyridyl)-2,6,10-triazaundecanenane, DIPN-pyr; 1,6-bis(2-pyridyl)-2,5-diazahexane, EN-pyr; and 1,7-bis(2-pyridyl)-2,6-diazaheptane, PN-pyr. The following methods were used to determine the binding geometries of the copper(II) complexes in the solid, solution, and gas phases: magnetic susceptibility measurements, absorption spectroscopy, EPR spectroscopy, electrochemistry, and electrospray ionization mass spectrometry. An X-ray structure was determined for the DIPN-pyr complex. The solid state structures were all found to be monomeric Cu(II) complexes with the coordination number set by the denticity of the ligand while the solution structures of all of the complexes except those with TRIPN-pyr and DIPN-pyr were found to be square pyramidal or elongated octahedral. The TRIPN-pyr and DIPN-pyr complexes showed considerable trigonal bipyramidal distortions. The gas phase data showed that the substitution of 6-membered for 5-membered chelate rings helped the ligand span more coordination sites. The TRIEN-pyr complex was 4- or 5-coordinate compared to the 5- or 6-coordination seen with the other three hexadentate ligands, and the DIPN-pyr complex was weakly 5-coordinate as compared to the 4-coordinate DIEN-pyr complex. The preferred structures of the ligands were consistent with their electrochemical behavior which showed the stability of the Cu(II) complex decreased in the order: DIPN-EN-pyr, TRIEN-pyr, DIEN-PN-pyr > DIEN-pyr > DIPN-pyr > TRIPN-pyr > PN-pyr > EN-pyr.

The synthesis and characterization of the copper(II) complexes of a series of aminopyridine ligands that range from tri- to heptadentate is described. The ligands include the tripod ligand tris(2-((2-pyridylmethyl)amino)ethyl)amine, TREN-pyr, and the following linear ligands: (2-pyridylmethyl)(2-(2-(2-((2-pyridylmethyl)amino)ethyl)amino)ethyl)amine, TRIEN-pyr; bis(2-((2-pyridylmethyl)amino)ethyl)amine, DIEN-pyr; (2-pyridylmethyl)(2-((2-pyridylmethyl)amino)ethyl)amine, EN-pyr; bis(2-pyridylmethyl)amine, AM-pyr; and methyl(2-((-pyridylmethyl)amino)ethyl)amine, MeEN-pyr. The following methods were used to determine the binding geometries of the Cu(II) complexes in the solid, solution, and gas phases: magnetic susceptibility measurements, absorption spectroscopy, EPR spectroscopy, electrochemistry, and analyzing the gas phase ion-molecule reactions in a mass spectrometer. The solid state structures for the TRIEN-pyr and DIEN-pyr complexes were determined by X-ray crystallography. [Cu(TRIEN-pyr)](BF 4 ) 2 crystallized in the octahedral system, space group Pbca , with a =9.4107(7), b =17.536(13), c =30.132(6) A, and Z =8 ( R =0.064, R w =0.060). [Cu(DIEN-pyr)](BF 4 ) 2 crystallized in the octahedral system, space group Pbca , with a =29.137(5), b =14.829(3), c =9.850(1) A, and Z =8 ( R =0.071, R w =0.066). The coordination numbers of the Cu(II) complexes in this study are dependent on the denticity of the ligand. The complexes with AM-pyr, MeEN-pyr and TRIEN-pyr appear to be six-coordinate, DIEN-pyr to be five-coordinate and the EN-pyr to be four-coordinate in the solid state. The TREN-pyr complex was isolated as a dimer in the solid state but appears to be a tetragonally distorted monomeric complex in the solution and gas phases. For all of the complexes except DIEN-pyr, the coordination sphere appears to be independent of the phase of the complex. The Cu(II) DIEN-pyr complex appears to be five-coordinate in the solid phase, a mixture of four- and five-coordinate in the solution phase, and predominately four-coordinate in the gas phase.

Two series of Ru(II) polypyridyl compounds with formulas [(bpy)2RuL](PF6)2 and [(deeb)2RuL](PF6)2, where bpy is 2,2'-bipyridine, deeb is 4,4'-diethylester-2,2'-bpy, and L is one of several substituted 9'-(1,3-dithiole-2-ylidene)-4',5'-diazafluorene ligands, were studied as potential photosensitizers for TiO2. These compounds possess notably high extinction coefficients (≥40,000 M(-1) cm(-1) @470 nm) which are shown by time-dependent density functional theory (TD-DFT) calculations to result from overlapping metal-to-ligand charge transfer (MLCT) and ligand-localized transitions. Low-temperature absorption and photoluminescence measurements were suggestive of a short-lived MLCT excited state. When adsorbed onto TiO2 thin films, both the free ligands (L) and their corresponding [(deeb)2RuL](2+) complexes exhibited rapid excited-state electron injection into TiO2; in the case of the complexes, this was followed by rapid (k10(8) s(-1)) hole transfer from Ru(III) to the 1,3-dithiole ring of the L ligand. Observation of diffusion-limited reductive quenching of the [Ru(bpz)3](2+)* (bpz is 2,2'-bipyrazine) excited state by the L ligands in solution supported the occurrence of intramolecular hole transfer following electron injection by the TiO2-anchored complexes.

The complex Cp★MoCl2(PMe2Ph)2 (Cp★ = η5C5Me5) has been obtained in good yield from Cp☆MoCl4, PMe2Ph2, and Na in the appropriate stoichiometric ratio, and it is also obtained by a ligand redistribution process after reduction of Cp☆MoCl3- (PMe2Ph) with Na. This compound is oxidized by the CH2Cl2 solvent in the presence of AlCl3 to afford the salt [Cp☆MoCl2(PMe2Ph)2AlCl4. Both compounds have been characterized crystallographically and by 1H-NMR spectroscopy. The reasons for the instability of 15-electron Cp☆MoCl2L complexes are discussed. The 1H-NMR resonance data for Cp ☆ MoCl 2 L 2 ( L = PMe 3 , PMe 2 Ph ) and [Cp☆MoCl2(PMe2Ph)2]+ are also discussed.

An ambidentate dicarboxylic acid bipyridine ligand, (4,5-diazafluoren-9-ylidene) malonic acid (dfm), was synthesized for coordination to Ru(II) and mesoporous nanocrystalline (anatase) TiO(2) thin films. The dfm ligand provides a conjugated pathway from the pyridyl rings to the carbonyl carbons of the carboxylic acid groups. X-ray crystal structures of [Ru(bpy)(2)(dfm)]Cl(2) and the corresponding diethyl ester compound, [Ru(bpy)(2)(defm)](PF(6))(2), were obtained. The compounds displayed intense metal-to-ligand charge transfer (MLCT) absorption bands in the visible region (ε11,000 M(-1) cm(-1) for [Ru(bpy)(2)(dfm)](PF(6))(2) in acetonitrile). Significant room temperature photoluminescence, PL, was absent in CH(3)CN but was observed at 77 K in a 4:1 EtOH:MeOH (v:v) glass. Cyclic voltammetry measurements revealed quasi-reversible Ru(III/II) electrochemistry. Ligand reductions were quasi-reversible for the diethyl ester compound [Ru(bpy)(2)(defm)](2+), but were irreversible for [Ru(bpy)(2)(dfm)](2+). Both compounds were anchored to TiO(2) thin films by overnight reactions in CH(3)CN to yield saturation surface coverages of 3 × 10(-8) mol/cm(2). Attenuated total reflection infrared measurements revealed that the [Ru(bpy)(2)(dfm)](2+) compound was present in the deprotonated carboxylate form when anchored to the TiO(2) surface. The MLCT excited states of both compounds injected electrons into TiO(2) with quantum yields of 0.70 in 0.1 M LiClO(4) CH(3)CN. Micro- to milli-second charge recombination yielded ground state products. In regenerative solar cells with 0.5 M LiI/0.05 M I(2) in CH(3)CN, the Ru(bpy)(2)(dfm)/TiO(2) displayed incident photon-to-current efficiencies of 0.7 at the absorption maximum. Under the same conditions, the diethylester compound was found to rapidly desorb from the TiO(2) surface.

A simple, qualitative demonstration of the vapor pressure lowering of aqueous solutions is presented. The demonstration consists of comparing two liquids, deionized water and a salt solution, in closed, glass containers. The difference in the degree of condensation inside of the two containers illustrates the difference in the vapor pressures of the two systems.

The reaction of crystalline lithium-stabilized Na-β”-Alumina with zirconium(IV) chloride at 400°C for 303h has caused sodium ions to exchange with zirconium ions. An X-ray crystal diffraction study of both the parent lithium stabilized Na-β”-alumina (1) and the partially zirconium exchanged product (2) have been made at 147 K. Crystal data for 1: rhombohedral, R 3 m, a = 5.6037 (3), c = 33.6210 (86) Å, V = 914.31 (24) Å3. Crystal data for 2: rhombohedral, R 3 m, a = 5.5994 (5), c = 33.7711 (51) Å, V = 916.96 (16) Å3. Zirconiums in 2 reside, predominately, in the Beevers-Ross type site.

The bicyclic molecule of the title compound, C9H12O3, contains two five-membered rings with different functional groups, viz. a ketone and an ester. Both rings assume an envelope conformation. The mean planes of these functional groups form a dihedral angle of 60.7 (1)°. The crystal structure exhibits weak intermolecular C—H...O interactions, which link the molecules into zigzag chains extended in the [010] direction. The unit cell contains a racemic mixture of enantiomers.

Crystals of the title compound, C23H17B3F3NO3, were obtained unintentionally by slow evaporation of a chloroform solution of the preformed boroxine–pyridine adduct. The molecule contains three fluoro-substituted benzene rings, each bonded to one of the three B atoms of a six-membered boroxine ring. A pyridyl ring is also bound to one of the B atoms through a Lewis acid–base interaction. The binding of the pyridyl substituent causes the otherwise planar boroxine ring to twist, resulting in a maximum torsion angle within the ring of 17.6 (2)°.

Two series of nickel-group metal bis(dithiolene) complexes with ligands 4,5-disulfanylcyclopent-4-ene-1,2,3-trionate (L1) and 2-dicyanomethylene-4,5-disulfanylcyclopent-4-ene-1,3-dionate (L2) have been prepared and characterized: [NBu4n]2[M(Li)2](M = Ni, Pd or Pt; i= 1 or 2). Oxidation of the dianion complexes yielded paramagnetic monoanions with ESR spectra indicative of a delocalized b3g HOMO (highest occupied molecular orbital), like that previously found for comparable bis(dithiolene) complexes. The intense low-energy visible absorptions and multiple, reversible reductions exhibited by the dianions likewise suggest that the LUMO (lowest unoccupied molecular orbital) is a ligand-based au(π*) orbital, rather than the b1g(dxy) orbital as commonly found for such complexes. The stabilization of the ligand-based LUMO in this case is attributed to the strongly electron-withdrawing character of the ligand substituents. Iodination of [NBu4n]2[Pd(L2)2] in CH2Cl2 solution yielded the novel iodine inclusion compound [NBun4]2[Pd(L2)2]·I2, which crystallizes in space group P with Z= 1, a= 10.792(3), b= 13.995(5), c= 10.737(3)A, α= 105.48(1), β= 115.15(1) and γ= 76.51(2)° at 25 °C. The I2 molecules are associated with the complex anions through short [3.1696(9)A] S ⋯ I contacts; however, the observed I–I distance [2.7354(4)A] indicates that the degree of charge transfer associated with this interaction is small.