[3-(Iodo­acetamido)prop­yl]triphenyl­phospho­nium tetra­phenyl­borate

Cameron Evans

doi:10.1107/S160053681000142X

. 2010 Jan 16;66(Pt 2):o384–o385. doi: 10.1107/S160053681000142X

[3-(Iodoacetamido)propyl]triphenylphosphonium tetraphenylborate

Cameron Evans ^a,^*

PMCID: PMC2979758 PMID: 21579806

Abstract

The title compound, C₂₃H₂₄INOP⁺·C₂₄H₂₀B⁻, was prepared by treatment of 3-aminopropyl triphenylphosphonium bromide hydrogen bromide with p-nitrophenyl iodoacetate at 203 K. The asymmetric unit contains a single cation and anion, which are linked in the crystal by intermolecular N—H⋯π and inversion-related R ₂ ²(14) C—H⋯O interactions, which combine to form chains of cations and anions along the c axis.

Related literature

For the development and applications of mitochondrially targeted bio-active compounds, see Murphy & Smith (2007 ▶); Porteous et al. (2010 ▶). For the use of iodoacetamides in labelling cysteine residues, see Baty et al. (2002 ▶); Kim et al. (2000 ▶); Ying et al. (2007 ▶). For the synthesis of aminoalkyl triphenylphosphonium salts, see McAllister et al. (1980 ▶). For the synthesis of iodoacetamides, see Trujillo et al. (1991 ▶). For related structures see Czerwinski (1986 ▶); Dubourg et al. (1986 ▶); Kerrigan et al.(1996 ▶); Lo et al.(2002 ▶). For a review of hydrogen bonding networks, see Bernstein et al.(1995 ▶).

Experimental

Crystal data

C₂₃H₂₄INOP⁺·C₂₄H₂₀B⁻
M _r = 807.51
Monoclinic,
a = 14.552 (3) Å
b = 12.108 (2) Å
c = 21.966 (4) Å
β = 99.49 (3)°
V = 3817.3 (13) Å³
Z = 4
Mo Kα radiation
μ = 0.92 mm⁻¹
T = 89 K
0.22 × 0.20 × 0.2 0mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2006 ▶) T _min = 0.661, T _max = 0.832
38267 measured reflections
9958 independent reflections
7291 reflections with I > 2σ(I)
R _int = 0.049

Refinement

R[F ² > 2σ(F ²)] = 0.037
wR(F ²) = 0.103
S = 1.11
9958 reflections
469 parameters
H-atom parameters constrained
Δρ_max = 0.74 e Å⁻³
Δρ_min = −0.99 e Å⁻³

Data collection: APEX2 (Bruker, 2006 ▶); cell refinement: APEX2 and SAINT (Bruker, 2006 ▶); data reduction: SAINT (Bruker, 2006 ▶); program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶) and Mercury (Macrae et al., 2006 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶), enCIFer (Allen et al., 2004 ▶) and publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S160053681000142X/nc2174sup1.cif

e-66-0o384-sup1.cif^{(31.1KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S160053681000142X/nc2174Isup2.hkl

e-66-0o384-Isup2.hkl^{(477.2KB, hkl)}

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

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

Cg is the centroid of the C61—C66 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯Cgⁱ	0.86	2.56	3.382 (2)	160
C1—H1B⋯O1ⁱⁱ	0.97	2.48	3.270 (3)	139

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

Acknowledgments

The author thanks Professor Robin Smith for access to materials and research facilities, and the BBSRC for financial support (contract No. BB/D020786/1).

supplementary crystallographic information

Comment

One aspect of our research into mitochondrially targeted bio-active agents (Murphy and Smith, 2007) involves synthesis of a series of targeted iodoacetamides from aminoalkyl-triphenylphosphonium salts (Porteous et al., 2010). The use of iodoacetamides in labelling of cysteine residues in proteins and peptides is well established (Ying et al., 2007) allowing attachment of key markers such as fluorescein (Baty et al., 2002) or biotin (Kim et al., 2000). Given the widespread use of the iodoacetamide functionality it is surprising that there appears to be no structural data available for non-aryl iodoacetamides.

The title compound crystallizes with one cation and anion in the asymmetric unit (Fig. 1). The bond distances within the iodoacetamide functionality [C(5)—I(1) 2.172 (3) Å, N(1)—C(4) 1.344 (3)Å and C(4)—O(1) 1.233 (3) Å] are equivalent to those reported for 4-chloro-7-(iodoacetyl)amino-3-methoxy isocoumarin [2.139 (9) Å, 1.363 (13)Å and 1.209 (14) Å; Kerrigan et al., 1996] and N-(ferrocenyl)iodoacetamide [2.152 (5) Å, 1.348 (6)Å and 1.234 (5) Å; Lo et al., 2002] indicating that the presence of the triphenylphosphonium cation has a negligible effect. The C(1)—P(1) [1.810 (3) Å] and C(3)—N(1) [1.462 (3) Å] distances mirror those observed for both dimethylamino-3-propyl triphenylphosphonium chloride [1.802 (3)Å and 1.496 (9) Å; Dubourg et al., 1986] and 2-aminoethyltriphenylphosphonium bromide hydrogen bromide [1.796 (5)Å and 1.512 (6) Å; Czerwinski, 1986].

The crystal packing is dominated by intermolecular N—H···π and C—H···O interactions (Fig. 2). The H(1)···CT and N(1)···CT distances [2.56Å and 3.382 (3) Å, where CT is the centroid of an adjacent C61—C66 ring on the tetraphenylborate anion] are indicative of a H-bonding interaction. In addition, there are inversion related C(1)—H(1B)···O(1) interactions [H(1B)···O(1) 2.48 Å, C(1)···O(1) 3.270 (3) Å] forming R²₂(14) ring motifs (Bernstein et al., 1995). The combination of these two types of interactions form chains of cations and anions as viewed along the c axis.

Experimental

The title compound was prepared from 3-aminopropyl triphenylphosphonium bromide hydrogen bromide (prepared using methods similar to McAllister et al., 1980) using a modified literature procedure (Trujillo et al., 1991). Triethylamine (0.43 mmol) was added to a dichloromethane solution (20 mL) of 3-aminopropyl triphenylphosphonium bromide hydrogen bromide (0.43 mmol), the solution cooled to -70°C and solid p-nitrophenyl iodoacetate (0.43 mmol) added in one portion. The solution was stirred at -70°C for 20 minutes and the solvent removed under vacuum. The solid residue was dissolved in acetone (5 mL), excess sodium tetraphenylborate (1 mmol) added and the solution stirred for 2 h at room temperature. Solvent was removed under vacuum, the compound redissolved in dichloromethane (2 mL) and precipitated by addition to diethylther (20 mL). Crystals were prepared by vapour diffusion of diethylether into an ethanolic solution of the compound at room temperature.