1-Methyl-1-azonia-3,5-diaza-7-phosphatricyclo­[3.3.1.13,7]decane tetra­fluoro­borate

Piotr Smoleński; Alexander M Kirillov; M Fátima C Guedes da Silva; Armando J L Pombeiro

doi:10.1107/S1600536808003401

. 2008 Feb 6;64(Pt 3):o556. doi: 10.1107/S1600536808003401

1-Methyl-1-azonia-3,5-diaza-7-phosphatricyclo[3.3.1.1^3,7]decane tetrafluoroborate

Piotr Smoleński ^a, Alexander M Kirillov ^a, M Fátima C Guedes da Silva ^a,^b,^*, Armando J L Pombeiro ^a

PMCID: PMC2960824 PMID: 21201899

Abstract

The title compound, C₇H₁₅N₃P⁺·BF₄ ⁻ or [PTA-Me][BF₄], is the N-methylated derivative of the well known water-soluble aminophosphine 1,3,5-triaza-7-phosphaadamantane (PTA). The asymmetric unit consists of a cage-like cation [PTA-Me]⁺ and a disordered tetrafluoroborate anion; two F atoms are disordered equally over two sites. A network of weak intermolecular C—H⋯F hydrogen bonds results in a three-dimensional supramolecular assembly.

Related literature

For general background, see: Kirillov et al. (2007 ▶); Smoleński & Pombeiro (2008 ▶). For a comprehensive review of PTA chemistry, see: Phillips et al. (2004 ▶). For the synthesis of PTA and [PTA-Me]I, see: Daigle et al. (1974 ▶); Daigle (1998 ▶). For related organic structures, see: Jogun et al. (1978 ▶); Forward et al. (1996 ▶); Otto et al. (2005 ▶); Kirillov et al. (2008 ▶). For related metal–organic structures, see: Kovacs et al. (2004 ▶); Smoleński et al. (2003 ▶); Pruchnik et al. (1999 ▶).

Experimental

Crystal data

C₇H₁₅N₃P⁺·BF₄ ⁻
M _r = 259.00
Orthorhombic,
a = 11.994 (2) Å
b = 11.6933 (18) Å
c = 15.569 (2) Å
V = 2183.5 (6) Å³
Z = 8
Mo Kα radiation
μ = 0.28 mm⁻¹
T = 150 (2) K
0.16 × 0.12 × 0.10 mm

Data collection

Bruker SMART CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2004 ▶) T _min = 0.956, T _max = 0.972
10402 measured reflections
1948 independent reflections
1391 reflections with I > 2σ(I)
R _int = 0.061

Refinement

R[F ² > 2σ(F ²)] = 0.045
wR(F ²) = 0.121
S = 1.05
1948 reflections
164 parameters
H-atom parameters constrained
Δρ_max = 0.55 e Å⁻³
Δρ_min = −0.36 e Å⁻³

Data collection: SMART (Bruker, 2004 ▶); cell refinement: SAINT (Bruker, 2004 ▶); data reduction: SAINT; program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: Mercury (Macrae et al., 2006 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808003401/hb2695sup1.cif

e-64-0o556-sup1.cif^{(16.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808003401/hb2695Isup2.hkl

e-64-0o556-Isup2.hkl^{(94KB, 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
C2—H2A⋯F2ⁱ	0.99	2.54	3.438 (3)	151
C5—H5A⋯F4ⁱⁱ	0.99	2.35	3.314 (3)	166
C6—H6B⋯F4	0.99	2.46	3.364 (3)	152
C11—H11B⋯F2ⁱⁱⁱ	0.98	2.43	3.350 (4)	156

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

This work was supported by the Foundation for Science and Technology (FCT) and its POCI 2010 programme (FEDER funded).

supplementary crystallographic information

Comment

Being interested in the coordination chemistry of aminophosphine 1,3,5-triaza-7-phospha-adamantane (PTA) and related ligands (Kirillov et al., 2007; Smoleński & Pombeiro, 2008), we have prepared compound (I) from the analogous salt, [PTA-Me]I (Daigle et al., 1974; Daigle, 1998), to determine the coordination behaviour of the [PTA-Me]⁺ species in the absence of iodide ions.

Compound (I) crystallizes in an orthorhombic crystal system and its unit cell is composed of a cage-like N-methylated [PTA-Me]⁺ cation whose positive charge is balanced by a disordered tetrafluoroborate anion (Fig. 1). The title compound appears to be isostructural to the related salt (Jogun et al., 1978) that possesses the same anion but the P-methylated [PTA-Me]⁺ cation. The geometrical parameters for (I) are comparable to those of other compounds with N-methylated PTA cores, either free (Kirillov et al., 2008; Otto et al., 2005; Forward et al., 1996) or coordinated to the metal centres (Kovacs et al., 2004; Smoleński et al., 2003; Pruchnik et al., 1999).

In (I), the [PTA-Me]⁺ units are disposed relatively close to the [BF₄]^- anions, thus allowing their extensive assembling via weak intermolecular C—H···F hydrogen bonds [mean C···F separation = 3.366 (3) Å], resulting in the formation of a three-dimensional supramolecular framework (Table 1, Fig. 2).

Experimental

An aqueous solution (25 ml) of [PTA-Me]I (1.00 mmol, 300 mg) and a methanolic (25 ml) solution of Tl[BF₄] (1.00 mmol, 300 mg) were combined at ambient temperature [Caution: Thallium compounds are highly toxic and thus must be handled with extreme caution]. The resulting white suspension was stirred for 15 min and then filtered off, giving a white powder of thallium iodide that was discarded. The colourless filtrate was evaporated in vacuo, resulting in a white solid. It was recrystallized from MeOH to furnish colourless plates of (I) in ca 80% yield (after isolation by filtration and drying in vacuo).

[PTA-Me][BF₄] is very soluble in middle-range polar solvents like Me₂CO, CHCl₃ and CH₂Cl₂, less soluble in H₂O, MeOH, EtOH and DMSO, and insoluble in C₆H₆, and Et₂O. FT–IR (KBr pellet), cm^-1: 2965 w, 2908 w, 1461 s, 1407 s, 1347 w, 1313 s, 1292 s, 1249 s, 1120 s, 1094 s br, 1023 s, 983 s, 920 s, 899 s, 815 s, 769 s, 748 m, 732 m, 687 w, 635 w, 557 s, 534 w and 440 w. ¹H NMR (300 MHz, D₂O, 25°C, Me₄Si): 4.86 and 4.75 (J(H^AH^B) = 11.4 Hz, 4H, NCH^AH^BN⁺), 4.52 and 4.36 (J(H^AH^B) = 13.8 Hz, 2H, NCH^AH^BN), 4.25 (d, ²J (H—P) = 6.8 Hz, 2H, PCH₂N⁺), 3.88 and 3.75 (J(H^AH^B) = 15.3 Hz, ³J(H^A—P) = 15.3 Hz, ³J(H^B—P) = 8.7 Hz, 4H, PCH^AH^BN), 2.66 (s, 3H, N⁺CH₃). ³¹P{¹H} NMR (121.4 MHz, D₂O, 25°C, 85% H₃PO₄): -85.7 (s).