Bis(triphenyl-λ5-phosphanylidene)ammonium hydrogen dichloride

Jorit Gellhaar; Carsten Knapp

doi:10.1107/S1600536811035057

. 2011 Sep 3;67(Pt 10):o2546. doi: 10.1107/S1600536811035057

Bis(triphenyl-λ⁵-phosphanylidene)ammonium hydrogen dichloride

Jorit Gellhaar ^a, Carsten Knapp ^a,^*

PMCID: PMC3201248 PMID: 22058726

Abstract

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.

Related literature

For selected examples containing the [Cl—H—Cl]⁻ anion, see: Atwood et al. (1990 ▶); Mootz et al. (1981 ▶); Habtemariam et al. (2001 ▶); Swann et al. (1984 ▶); Neumüller et al. (2005 ▶). For other bis(triphenyl-λ⁵-phosphanylidene)ammonium halide structures, see: Knapp & Uzun (2010a ▶,b ▶); Beckett et al. (2010 ▶). For a discussion of the [(Ph₃P)₂N]⁺ cation, see: Lewis & Dance (2000 ▶). For a description of the Cambridge Structural Database, see: Allen (2002 ▶). For the synthesis of [(Ph₃P)₂N]Cl, see: Ruff & Schlientz (1974 ▶).

Experimental

Crystal data

C₃₆H₃₀NP₂ ⁺·Cl₂H⁻
M _r = 610.46
Orthorhombic,
a = 11.6467 (3) Å
b = 16.5474 (4) Å
c = 15.7584 (3) Å
V = 3037.00 (12) Å³
Z = 4
Mo Kα radiation
μ = 0.35 mm⁻¹
T = 100 K
0.18 × 0.14 × 0.09 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2001 ▶) T _min = 0.940, T _max = 0.970
28633 measured reflections
2994 independent reflections
2671 reflections with I > 2σ(I)
R _int = 0.030

Refinement

R[F ² > 2σ(F ²)] = 0.033
wR(F ²) = 0.085
S = 1.08
2994 reflections
189 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.61 e Å⁻³
Δρ_min = −0.79 e Å⁻³

Data collection: APEX2 (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg & Putz, 2011 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811035057/su2304sup1.cif

e-67-o2546-sup1.cif^{(24.2KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811035057/su2304Isup2.hkl

e-67-o2546-Isup2.hkl^{(147KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
Cl1—H1⋯Cl1ⁱ	1.56 (1)	1.56 (1)	3.1045 (9)	173 (3)

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Symmetry code: (i) Inline graphic .

Acknowledgments

Financial support from the Deutsche Forschungsgemeinschaft (DFG) and Universität Freiburg is gratefully acknowledged.

supplementary crystallographic information

Comment

The Cambridge Structural Database (Allen, 2002) currently contains more than 1200 structures containing the [(Ph₃P)₂N]⁺ cation ([(Ph₃P)₂N]⁺ = [PNP]⁺). Usually this cation is partnered by a bulky anion, while crystal structures containing small anions and especially halides are rare. The crystal structures of some solvate-free halides, [(Ph₃P)₂N]I (Beckett et al., 2010) and [(Ph₃P)₂N]Cl (Knapp & Uzun, 2010a), and the acetontrile solvate [(Ph₃P)₂N]Br^.CH₃CN (Knapp & Uzun, 2010b), were published only very recently.

Bis(triphenyl-λ⁵-phosphanylidene)ammonium chloride [(Ph₃P)₂N]Cl was synthesized according to a published method (Ruff et al., 1974). Solvate-free single crystals suitable for X-ray diffraction of the title compound were obtained as a by-product by layering a CH₃CN solution with diethyl ether. 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 the cation. The central P—N—P angle [144.12 (13)°] and the P—N [1.5762 (7) Å] and P—C distances [1.7940 (16)–1.8028 (15) Å] are in the expected range for the [(Ph₃P)₂N]⁺ cation (Lewis & Dance, 2000).

The number of structurally characterized hydrogen dichloride anions is still limited. Often disorder or low crystal quality does not allow to establish unequivically the position of the H atom. The Cl···Cl distances in all hydrogen dichloride anions deviate only slightly from an averaged distance of 3.10 Å. The anion in the title compound contains a symmetric hydrogen bridge with H—Cl distances of 1.56 (1) Å and a Cl···Cl distance of 3.1045 (9) Å. The anion is almost linear and a Cl—H—Cl angle of 173 (3)° is observed. A very similar hydrogen dichloride anion was found in the the crystal structure of [K(18 C-6)][Cl—H—Cl], where H—Cl is 1.56 Å and Cl···Cl 3.117 (1) Å (Atwood et al., 1990).

Experimental

Single crystals of the title compound, suitable for X-ray diffraction analysis, were obtained as a by-product by layering a CH₃CN solution of [(Ph₃P)₂N]Cl with diethyl ether.