Molecular structures of M(Bu(t))3 (M = Al, Ga, In) using gas-phase electron diffraction and ab initio calculations: experimental and computational evidence for charge-transfer processes leading to photodissociation.

The gas-phase structures of AI(Bu')3 and Ga(Bu')3 have been investigated by electron diffraction and are shown to consist of monomeric units with very slightly pyramidal geometries. Salient structural parameters (r(hl)) include r(A1-C) = 2.008(2) A and r(Ga-C) = 2.

Accurate equilibrium structures obtained from gas-phase electron diffraction data: sodium chloride.

A novel method has been developed to allow the accurate determination of equilibrium gas-phase structures from experimental data, thus allowing direct comparison with theory. This new method is illustrated through the example of sodium chloride vapor at 943 K. Using this approach the equilibrium structures of the monomer (NaCl) and the dimer (Na(2)Cl(2)), together with the fraction of vapor existing as dimer, have been determined by gas-phase electron diffraction supplemented with data from microwave spectroscopy and ab initio calculations.

The molecular structure of N-fluorobis(trifluoromethanesulfonyl)imide, NF(SO(2)CF(3))(2), as studied in the gas phase by electron diffraction restrained by ab initio calculations.

The structure of N-fluorobis(trifluoromethylsulfonyl)imide, prepared by a relatively safe and easy method, has been determined by gas-phase electron diffraction (GED), employing the SARACEN method, with flexible restraints based on the MP2/6-311G* structure, and by X-ray crystallography at 150 K. The strongly electron-withdrawing CF(3) and SO(2)CF(3) groups make the C-S and N-S distances long, averaging 187.7(3) and 171.

Gas-phase structure of (1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)(eta(2)-1,5-cyclooctadiene)copper(I), Cu(1,5-cod)(hfac), an important precursor for vapor deposition of copper.

The molecular structure of Cu(1,5-cod)(hfac) in the gas phase has been determined by electron diffraction, restrained by parameters calculated ab initio (MP2/AE1 level) or using Density Functional Theory (BP86/AE1 level). The most stable structure is one in which one olefinic group of the cyclooctadiene ligand is coordinated to the square-planar copper atom [refined Cu-C distances 194.0(13) and 194.

Molecular Structure of Chlorodifluoronitrosomethane, CClF(2)NO, As Determined in the Gas Phase by Electron Diffraction and ab Initio Calculations.

The gas-phase structure of chlorodifluoronitrosomethane, CClF(2)NO, has been determined by electron diffraction and calculated ab initio. Theoretically, CClF(2)NO is predicted to consist of two conformers having C(s)() (phi = 0 degrees ) and C(1) (phi = 105 degrees ) symmetry, which are near degenerate in energy, DeltaE = 1.1 kJ mol(-1) [TZ2P/MP2 + ZPE(DZP/MP2)], and separated by a barrier of around 1 kJ mol(-1).

Gas-Phase Reaction of Tetraborane(10) and Ethyne: Molecular Structure of nido-1,2-C(2)B(3)H(7) in the Gas Phase.

The molecular structure of nido-1,2-C(2)B(3)H(7), 1, the principal volatile carborane generated in the quenched gas-phase reaction of B(4)H(10) and ethyne at 70 degrees C, has been determined by a combined analysis of gas-phase electron-diffraction data and rotation constants restrained by ab initio computations at the CCSD(T)/TZP' level. The structure is consistent with a geometry having C(s)() symmetry, similar to that of pentaborane(9). The apical position is occupied by a carbon atom, displaced toward B(4) from a position directly above the B(5).

Differences Between Gas-Phase and Solid-State Molecular Structures of the Simplest Phosphonium Ylide, Me P=CH.

Clearly different from local C symmetric is the heavy-atom core of Me P=CH , the simplest phosphonium ylide. The geometry obtained by reanalysis of gas-electron-diffraction data from 1977 is now consistent with theoretical calculations, but different from the molecular structure in the solid state. The picture shows the structure of Me P=CH in the gas phase (a) and in the crystal (c) together with the calculated transition state (b) (viewed along the P=C bond).

Molecular Structure of 3,4-Dimethylenehexa-1,5-diene ([4]Dendralene), C(8)H(10), in the Gas Phase As Determined by Electron Diffraction and ab Initio Calculations.

The molecular structure of 3,4-dimethylenehexa-1,5-diene ([4]dendralene), C(8)H(10), has been determined in the gas phase. A single conformer with C(2) symmetry, having two almost planar, anti butadiene groups orientated with a dihedral angle C(2)C(3)C(4)C(5) of 71.7(19) degrees, is detected by electron diffraction employing flexible restraints derived from ab initio computations.

Molecular Structure of Trifluorophosphine Tetraborane(8), B(4)H(8)PF(3), As Determined in the Gas Phase by Electron Diffraction and ab Initio Computations.

The molecular structure of trifluorophosphine tetraborane(8), B(4)H(8)PF(3), has been studied in the gas phase by electron diffraction. The experimental data can be fitted using a model which represents the gas as consisting solely of the endo conformer with C(s)() symmetry, the PF(3) group staggered with respect to the B(1)-H(1) bond. Important experimental structural parameters (r(alpha) degrees ) are r[B(1)-B(2)] (hinge-wing) = 184.

Molecular Structures of Methyldifluoroarsine, CH(3)AsF(2), and Dimethylfluoroarsine, (CH(3))(2)AsF, in the Gas Phase As Determined by Electron Diffraction and ab InitioCalculations.

The structures of gaseous CH(3)AsF(2) and (CH(3))(2)AsF have been determined by electron diffraction incorporating vibrational amplitudes derived from ab initio force fields scaled by experimental frequencies and, for the difluoride, restrained by microwave constants. The following parameters (r(alpha) degrees structure, distances in pm, angles in degrees) have been determined for CH(3)AsF(2): r(As-C) = 194.6(4), r(As-F) = 173.

1-Phenyl-1,2-dicarba-closo-dodecaborane, 1-Ph-1,2-closo-C(2)B(10)H(11). Synthesis, Characterization, and Structure As Determined in the Gas Phase by Electron Diffraction, in the Crystalline Phase at 199 K by X-ray Diffraction, and by ab Initio Computations.

The compound 1-phenyl-1,2-dicarba-closo-dodecaborane(12), 1-C(6)H(5)-1,2-closo-C(2)B(10)H(11) (1), has been synthesized and characterized by a complete assignment of its (11)B NMR spectrum via (11)B{(1)H}/(11)B{(1)H} (COSY), (1)H{(11)B(selective)} and (1)H{(11)B}/(1)H{(11)B} (COSY) spectroscopy. An electron- and X-ray diffraction investigation of 1, complemented by ab initio calculations, has been undertaken. The gas-phase electron-diffraction (GED) data can be fitted by several models describing conformations which differ in the position of the phenyl ring with respect to the carborane cage.