Bis(triphenylphosphine)iminium bromide acetonitrile monosolvate

Temperature- and solvate-dependent disorder in the crystal structure of [PNP]+[HSO4]−

Metathesis reactions of [PNP]Cl ([PNP]+ ≡ bis(triphenyl-λ 5-phosphanylidene)ammonium) with Na2[SO4] or K[HSO4] in water yield [PNP]2[SO4] and [PNP][HSO4], respectively, as colorless solids. Reactions under basic conditions lead to a partial decomposition of the weakly coordinating [PNP]+ cation. N-Diphenylphosphine-triphenylphosphazene, triphenylphosphinimine, and benzene were identified as decomposition products by NMR spectroscopy. The compounds [PNP]2[SO4] and [PNP][HSO4] were characterized by multinuclear NMR and vibrational spectroscopy. [PNP][HSO4] could be crystallized from acetonitrile-diethyl ether giving single crystals with and without additional acetonitrile solvate molecules. The [HSO4]− anions form dimers in the solid state in both structures, which are held together by O–H⋯O hydrogen bonds. At T = 127 K the [HSO4]− anions in the crystal structure of solvate free [PNP][HSO4] are ordered, while at T = 300 K and in the structure containing additional acetonitrile solvate molecules a disorder of the [HSO4]− anions over two positions is observed, for the latter even at 150 K.

Theoretical and Synthetic Study on the Existence, Structures, and Bonding of the Halide-Bridged [B2X7](-) (X = F, Cl, Br, I) Anions

While hydrogen bridging is very common in boron chemistry, halogen bridging is rather rare. The simplest halogen-bridged boron compounds are the [B2X7](-) anions (X = F, Cl, Br, I), of which only [B2F7](-) has been reported to exist experimentally. In this paper a detailed theoretical and synthetic study on the [B2X7](-) anions is presented. The structures of [B2X7](-) anions have been calculated at the MP2/def2-TZVPP level of theory, and their local minima have been shown to be of C2 symmetry in all cases. The bonding situation varies significantly between the different anions. While in [B2F7](-) the bonding is mainly governed by electrostatics, the charge is almost equally distributed over all atoms in [B2I7](-) and additional weak iodine···iodine interactions are observed. This was shown by an atoms in molecules (AIM) analysis. The thermodynamic stability of the [B2X7](-) anions was estimated in all phases (gas, solution, and solid state) based on quantum-chemical calculations and estimations of the lattice enthalpies using a volume-based approach. In the gas phase the formation of [B2X7](-) anions from [BX4](-) and BX3 is favored in accord with the high Lewis acidity of the BX3 molecules. In solution and in the solid state only [B2F7](-) is stable against dissociation. The other three anions are borderline cases, which might be detectable under favorable conditions. However, experimental attempts to identify [B2X7](-) (X = Cl, Br, I) anions in solution by (11)B NMR spectroscopy and to prepare stable [PNP][B2X7] salts failed.

The N-atom in [N(PR3)2]+ cations (R = Ph, Me) can act as electron donor for (pseudo) anti-electrostatic interactions

A CSD analysis and DFT study reveal that the nitrogen lone-pair in [N(PPh₃)₂]⁺ is partially intact and involved in intramolecular hydrogen bonding.

A second polymorph of bis-(triphenyl-λ(5)-phosphanyl-idene)ammonium chloride-boric acid adduct

The title crystal structure is a new triclinic polymorph of [(Ph3P)2N]Cl·(B(OH)3) or C36H30NP2 (+)·Cl(-)·BH3O3. The crystal structure of the ortho-rhom-bic polymorph was reported by [Andrews et al. (1983 ▶). Acta Cryst. C39, 880-882]. In the crystal, the [(Ph3P)2N](+) cations have no significant contacts to the chloride ions nor to the boric acid mol-ecules. This is indicated by the P-N-P angle of 137.28 (8)°, which is in the expected range for a free [(Ph3P)2N](+) cation. The boric acid mol-ecules form inversion dimers via pairs of O-H⋯O hydrogen bonds, and each boric acid mol-ecule forms two additional O-H⋯Cl hydrogen bonds to one chloride anion. These entities fill channels, created by the [(Ph3P)2N](+) cations, along the c-axis direction.

Bis(triphenyl-λ-phosphanylidene)ammonium hydrogen dichloride

In the title compound, [(Ph₃P)₂N]⁺·[Cl-H-Cl]⁻ or C₃₆H₃₀NP₂⁺·Cl₂H⁻, the H atom of the [Cl—H—Cl]⁻ anion and the N atom of the [(Ph₃P)₂N]⁺ cation are located on a twofold axis, yielding overall symmetry 2 for both the cation and the anion. The central P—N—P angle [144.12 (13)°] of the cation is in the expected range and indicates only weak cation–anion inter­actions. The almost linear [Cl—H—Cl]⁻ anion is a rare example of a symmetric hydrogen bridge in a hydrogen dichloride anion. The Cl⋯Cl distance and two equal Cl—H bonds are typical of such a symmetric hydrogen dichloride anion.

Solvate-free bis-(triphenylphosphine)iminium chloride

The title compound, C₃₆H₃₀NP₂⁺·Cl⁻, crystallized in the solvate-free form from a CH₃CN/OEt₂ solution. The chloride anion and the N atom of the [(Ph₃P)₂N]⁺ cation are located on a twofold axis, yielding overall symmetry 2 for the cation. The central P—N—P angle [133.0 (3)°] is at the low end of the range of observed P—N—P angles.