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organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoSTRUCTURAL
CHEMISTRY
ISSN: 2053-2296
Volume 62| Part 11| November 2006| Pages o656-o658
doi:10.1107/S0108270106039825

Solvent-free synthesis and crystal structure of (Ph3PI)I5, the third member in the series Ph3P(I2)n (n = 1, 2 and 3)

CROSSMARK_Color_square_no_text.svg
Robin G. Pritcharda* and Lee Morelanda

aSchool of Chemistry, Faraday Building, University of Manchester, Sackville Street, Manchester M60 1QD, England
*Correspondence e-mail: robin.pritchard@manchester.ac.uk

(Received 29 August 2006; accepted 27 September 2006; online 19 October 2006)

Red crystals of iodo­triphenyl­phospho­nium penta­iodide, C18H15IP+·I5−, appear on cooling the black melt formed by heating a mixture of the commonplace reagents triphenyl­phosphine and mol­ecular iodine. The compound has the highest I:P ratio hitherto established for a crystalline iodo­phospho­nium polyiodide and constitutes the third member of the series Ph3P(I2)n (n = 1, 2 and 3). All atoms occupy general positions in the triclinic space group P[\overline{1}]. Comparison of the bond lengths within the above series reveals a pattern of primary and secondary bonding that is highly reminiscent of the much studied polyiodides, I−2n+1, where one of the I2 moieties has been replaced by a P—I group.

Comment

Classification of adducts formed by combining the common reagents I2 and Ph3P has not been straightforward. The 1:1 adduct crystallizes from diethyl ether as the mol­ecular compound Ph3PI2 (Godfrey et al., 1991[Godfrey, S. M., Kelly, D. G., McAuliffe, C. A., Mackie, A. G., Pritchard, R. G. & Watson, S. M. (1991). J. Chem. Soc. Chem. Commun. pp. 1163-1164.]), (1), which remains un-ionized even when dissolved in dichloro­ethane (Deplano et al., 1997[Deplano, P., Godfrey, S. M., Isaia, F., McAuliffe, C. A., Mercuri, M. L. & Trogu, E. F. (1997). Chem. Ber. 130, 299-305.]). By contrast, the 2:1 adduct forms ionically diverse polymorphs, viz. (Ph3PI)I3, (2a), from toluene and [(Ph3PI)2I3]I3, (2b), from dichloro­ethane (Cotton & Kibala, 1987[Cotton, F. A. & Kibala, P. A. (1987). J. Am. Chem. Soc. 109, 3308-3312.]). This type of polymorphism, although not unknown (Katrusiak, 2003[Katrusiak, A. (2003). Org. Lett. 5, 1903-1905.]), is extremely rare and serves as a graphic illustration of the sensitivity of iodo­phospho­nium polyiodides to solvent effects. In this case, the more polar solvent encourages auto-ionization and charge separation in what is already an extremely polarized species:

2(Ph3PI)I3 → [(Ph3PI)2I3]+ + I3−

Indeed, (2b) is best described as an ion pair associating through a weak charge-transfer bond. The above structures represent the highest I:P ratio hitherto achieved in the Ph3P/I2 system and it is noteworthy that an iodo­phospho­nium polyiodide structure with an I:P ratio of 6 or higher has yet to be reported. This is somewhat surprising given the ionic behavior outlined above and the fact that several mol­ecular cations are

[Scheme 1]
known to form compounds with large polyiodide counter-ions, e.g. Me3S+ forms a series of crystalline polyiodides, including one in which the I:P ratio exceeds 8 (Svensson et al., 2000[Svensson, P. H., Raud, G. & Kloo, L. (2000). Eur. J. Inorg. Chem. pp. 1275-1282.]), and [Et3S]Ix (x > 4) forms polyiodide melts in which non-polar I2 is considered to be behaving as a solvent (Bengtsson et al., 1991[Bengtsson, L. A., Stegemann, H., Holmberg, B. & Fullbier, H. (1991). Mol. Phys. 73, 283-296.]). The current investigation was therefore undertaken in order to discover how Ph3P would react with I2 when freed from the influence of conventional solvents. Direct reaction of molten Ph3P with I2 produced the title compound, (Ph3PI)I5, (3)[link] (Fig. 1[link]). Compound (3)[link] is clearly related to (2a), the 2:1 polymorph grown in toluene, and forms the third member of the series Ph3P(I2)n (n = 1, 2 and 3). This series, in turn, has strong similarities with the extensively studied polyiodides I2n+1- (n = 1, 2, 3 and 4), where I− replaces Ph3P as the base (Svensson & Kloo, 2003[Svensson, P. H. & Kloo, L. (2003). Chem. Rev. 103, 1649-1684.]).

Polyiodides are classified according to their I—I bond lengths, e.g. I5− can be described as V-shaped [(I−)·2I2] or L-shaped [(I3−)·(I2)], depending on the pattern of inter­atomic distances. Furthermore, below 3.3 Å (Coppens, 1982[Coppens, P. (1982). Extended Linear Chain Compounds, edited by J. S. Miller, Vol. 1, ch. 7, pp. 333-356. New York: Plenum Press.]) or, arguably, 3.4 Å (Svensson & Kloo, 2003[Svensson, P. H. & Kloo, L. (2003). Chem. Rev. 103, 1649-1684.]), the bonds are considered to be intra­molecular or primary bonds. Above these values up to 3.7 Å, the bonds are defined as inter­molecular or secondary and up to 3.9 Å as weak van der Waals inter­actions. The same rationale can be used to classify iodo­phospho­nium polyiodide structures, with the proviso that P—I bonds are always primary. Alternatively, a more inclusive scheme based on bond order can easily be set up using empirical bond length versus bond order (n) relationships.

An existing equation, viz. I—I = 2.67 − 0.85log10(n) (Bürgi, 1975[Bürgi, H.-B. (1975). Angew. Chem. Int. Ed. Engl. 14, 460-473.]), allows the above bond-length ranges to be converted into bond orders, primary above 0.18 (or 0.14) and secondary down to 0.06. Also, as the crystal structures of several R3PI2 adducts are now known, a similar equation, P—I = 2.35 − 1.14log10(n), can be derived for P—I bonds by assuming nI—P = 1 − nI—I (Fig. 2[link]). The subsequent bond orders, calculated by applying these equations to crystallographically determined bond lengths from the Ph3P(I2)n series (Fig. 3[link]), clearly justify the assignment of Ph3PI2 and (Ph3PI)I3 to compounds (1) and (2), respectively. Also, based on these values, (Ph3PI)I5 is the most appropriate description of (3)[link].

Further support for these assignments comes from solution work carried out in dichloro­ethane, where I3− and I5− ions were detected but not I− (Deplano et al., 1997[Deplano, P., Godfrey, S. M., Isaia, F., McAuliffe, C. A., Mercuri, M. L. & Trogu, E. F. (1997). Chem. Ber. 130, 299-305.]). These iodo­phospho­nium polyiodide structures are analogous to known polyiodide types: (1) corresponds to a typical asymmetric I3−, (2a) to an L-shaped (I3−)·I2 and (3)[link] to pyramidal (I5−)·I2. In each case, the P—I moiety behaves like a low acidity, but by no means inert, I2. More detailed examination of (3)[link] shows that the I5− part is nearly V-shaped, i.e. (I−)·2I2, and as the bond order of the inter­molecular bond is close to an intra­molecular value it is worth noting that (3)[link] is bordering on (Ph3PI)(I2)2I cf. (I−)(I2)3.

The close parallels between the iodo­phospho­nium polyiodides and polyiodides extend to their secondary inter­actions. Compound (2a) associates into a trans-chain, one of the common contact geometries for penta­iodides (Svensson & Kloo, 2003[Svensson, P. H. & Kloo, L. (2003). Chem. Rev. 103, 1649-1684.]), by head-to-tail linking of adjacent I3− groups via a 3.741 (1) Å (n = 0.05) secondary bond. A stronger secondary bond of 3.601 (1) Å (n = 0.08) links (3)[link] into a cis-chain (Fig. 4[link]), which can be pictured as evolving from the trans-chain by adding an extra I2 side branch opposite the IPPh3 moiety and then twisting the chain from trans to cis. This type of extended structure is also seen in the hepta­iodide [H3O·18-crown-6]I7, where it has been described as a sawhorse (Abd El Khalik et al., 1999[Abd El Khalik, S., El Essawi, M., Dombrowski, I. & Tebbe, K. F. (1999). Z. Naturforsch. Teil B, 54, 136-139.]; Junk et al., 1995[Junk, P. C., Macgillivray, L. R., May, M. T., Robinson, K. D. & Atwood, J. L. (1995). Inorg. Chem. 34, 5395-5396.]).

The current, solvent-free, work has broadened our understanding of iodo­phospho­nium polyiodides and, perhaps more importantly, established clear parallels between the Ph3P(I2)n and I2n+1- structures, suggesting that crystals with even higher iodine loadings may well be attainable. Despite the cursory nature of our observations on the melt associated with the formation of (3)[link], there is sufficient evidence to suggest that research along the lines of that carried out on polyiodide melts (Bengtsson et al., 1991[Bengtsson, L. A., Stegemann, H., Holmberg, B. & Fullbier, H. (1991). Mol. Phys. 73, 283-296.]) may well prove fruitful in this case too.

[Figure 1]
Figure 1
The mol­ecular structure of (Ph3PI)I5, showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
[Figure 2]
Figure 2
The variation of P—I bond length (Å) with bond order n. (I) is (2-Me-1,2-C2B10H10)(iPr)2PI2 (Teixidor et al., 2000[Teixidor, F., Núñez, R., Viñas, C., Sillanpää, R. & Kivekäs, R. (2000). Angew. Chem. Int. Ed. 39, 4290-4292.]), (II) is Ph3PI2 (Godfrey et al., 1991[Godfrey, S. M., Kelly, D. G., McAuliffe, C. A., Mackie, A. G., Pritchard, R. G. & Watson, S. M. (1991). J. Chem. Soc. Chem. Commun. pp. 1163-1164.]), (III) is [C6H2(OMe)3]3PI2·CH2Cl2 (Godfrey et al., 1998[Godfrey, S. M., McAuliffe, C. A., Pritchard, R. G. & Sheffield, J. M. (1998). J. Chem. Soc. Dalton Trans. pp. 1919-1923.]), (IV) is (tBu)3PI2 (DuMont et al., 1987[DuMont, W. W., Batcher, M., Pohl, S. & Saak, W. (1987). Angew. Chem. Int. Ed. Engl. 26, 912-913.]), (V) is (iPr)3PI2·CH2Cl2 (Ruthe et al., 2000[Ruthe, F., Jones, P. G., du Mont, W. W., Deplano, P. & Mercuri, M. L. (2000). Z. Anorg. Allg. Chem. 626, 1105-1111.]) and (VI) is PhMe2PI2 (Bricklebank et al., 1995[Bricklebank, N., Godfrey, S. M., Lane, H. P., McAuliffe, C. A., Pritchard, R. G. & Moreno, J. M. (1995). J. Chem. Soc. Dalton Trans. pp. 2421-2424.]).
[Figure 3]
Figure 3
Empirically derived bond orders for Ph3P(I2)n (n = 1, 2 and 3).
[Figure 4]
Figure 4
The sawhorse structure of (3)[link], formed through association of pyramidal Ph3PI(I5) units via secondary bonds.

Experimental

The title compound was prepared by placing powdered Ph3P in a 0.7 mm diameter special-glass X-ray sample tube to a depth of ca 10 mm, using a second tube as a funnel to prevent the glass becoming contaminated. Approximately the same quantity of fine I2 crystals was added immediately prior to the tube being evacuated with a rotary pump and flame sealed. Although a narrow brown layer appeared instantaneously at the inter­face between the two materials, it did not develop further until the tube was heated to the melting point of Ph3P. At this point, the I2 crystals and their violet vapour disappeared to be replaced by a black melt which extended for several mm over the inter­face region. On cooling, red crystals of Ph3PI(I5), (3)[link], were recovered by breaking the glass tube under inert oil.

Crystal data

  • C18H15IP+·I5−

  • Mr = 1023.67

  • Triclinic, [P \overline 1]

  • a = 9.4288 (3) Å

  • b = 11.7262 (4) Å

  • c = 12.1270 (5) Å

  • α = 86.196 (1)°

  • β = 77.290 (1)°

  • γ = 77.697 (1)°

  • V = 1277.66 (8) Å3

  • Z = 2

  • Dx = 2.661 Mg m−3

  • Mo Kα radiation

  • μ = 7.36 mm−1

  • T = 150 (2) K

  • Block, dark red

  • 0.1 × 0.1 × 0.05 mm
Data collection

  • Nonius KappaCCD area-detector diffractometer

  • φ and ω scans

  • Absorption correction: multi-scan (Blessing, 1995[Blessing, R. H. (1995). Acta Cryst. A51, 33-38.], 1997[Blessing, R. H. (1997). J. Appl. Cryst. 30, 421-426.]) Tmin = 0.478, Tmax = 0.683

  • 5574 measured reflections

  • 5262 independent reflections

  • 3809 reflections with I > 2σ(I)

  • Rint = 0.067

  • θmax = 26.5°
Refinement

  • Refinement on F2

  • R[F2 > 2σ(F2)] = 0.053

  • wR(F2) = 0.146

  • S = 1.07

  • 5262 reflections

  • 226 parameters

  • H-atom parameters constrained

  • w = 1/[σ2(Fo2) + (0.0677P)2 + 14.7624P] where P = (Fo2 + 2Fc2)/3

  • (Δ/σ)max = 0.001

  • Δρmax = 2.20 e Å−3

  • Δρmin = −1.42 e Å−3

Table 1
Selected geometric parameters (Å, °)

C1—P 1.784 (10)
C7—P 1.790 (10)
C13—P 1.797 (12)
P—I1 2.412 (3)
I2—I3 3.1022 (11)
I3—I4 2.7906 (13)
I5—I6 2.7709 (10)
C1—P—C7 109.9 (5) 
C1—P—C13 110.6 (5)
C7—P—C13 109.9 (5)
C1—P—I1 109.4 (3)
C7—P—I1 107.8 (3)
C13—P—I1 109.2 (4)
I4—I3—I2 179.57 (4)
C2—C1—P—I1 −28.2 (10) 
C8—C7—P—I1 −54.7 (9)
C14—C13—P—I1 129.7 (9)

As the melt-grown crystals formed as a fused mass, it proved difficult to select an ideal crystal. Despite this, a reasonable quality data set was obtained, enabling the structure to be solved and subsequently refined in the space group P[\overline{1}] (No. 2). Some peaks as high as 2.2 e Å−3 remained in the difference Fourier map. These peaks shared y and z coordiates with I atoms but were shifted in the x direction. Since a twinned refinement did not affect the size of the extra peaks or improve the R factors, a twinned model was rejected. It is suggested that stacking faults may occur along the a axis, which coincides with the backbone of the sawhorse. H atoms were constrained to chemically reasonable positions, with C—H = 0.95 Å and Uiso(H) = 1.2Ueq(C).

Data collection: COLLECT (Nonius, 1998[Nonius (1998). COLLECT. Nonius BV, Delft, The Netherlands.]); cell refinement: SCALEPACK (Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press.]); data reduction: SCALEPACK and DENZO (Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press.]); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.]); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997[Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.]); software used to prepare material for publication: WinGX (Farrugia, 1999[Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837-838.]).

Supporting information

Crystal structure: contains datablocks global, 3. DOI: 10.1107/S0108270106039825/bc3017sup1.cif

Structure factors: contains datablock 3. DOI: 10.1107/S0108270106039825/bc30173sup2.hkl


Comment top

The classification of adducts formed by combining the common reagents I2 and Ph3P has not been straightforward. The 1:1 adduct crystallizes from diethyl ether as the molecular compound Ph3PI2 (Godfrey et al., 1991), (1), which remains unionized even when dissolved in dichloroethane (Deplano et al., 1997). By contrast, the 2:1 adduct forms ionically diverse polymorphs, (Ph3PI)I3, (2a), from toluene and [(Ph3PI)2I3]I3, (2b), from dichloroethane (Cotton & Kibala, 1987). This type of polymorphism, although not unknown (Katrusiak, 2003), is extremely rare and serves as a graphic illustration of the sensitivity of iodophosphonium polyiodides to solvent effects. In this case, the more-polar solvent encourages auto-ionization and charge separation in what is already an extremely polarized species: 2(Ph3PI)I3 → [(Ph3PI)2I3]+ + I3−

Indeed, (2b) is best described as an ion pair associating through a weak charge-transfer bond. The above structures represent the highest I:P ratio hitherto achieved in the Ph3P/I2 system and it is noteworthy that an iodophosphonium polyiodide structure with an I:P ratio of 6 or higher has yet to be reported. This is somewhat surprising given the ionic behavior outlined above and the fact that several molecular cations are known to form compounds with large polyiodo counter-ions, e.g. Me3S+ forms a series of crystalline polyiodides, including one in which the I:P ratio exceeds 8 (Svensson et al., 2000), and [Et3S]Ix (x > 4) forms polyiodide melts in which non-polar I2 is considered to be behaving as a solvent (Bengtsson et al., 1991). The current investigation was therefore undertaken in order to discover how Ph3P would react with I2 when freed from the influence of conventional solvents. Direct reaction of molten Ph3P with I2 produced the title compound, (Ph3PI)I5, (3) (Fig. 1). Compound (3) is clearly related to (2a), the 2:1 polymorph grown in toluene, and forms the third member of the series Ph3P(I2)n (n = 1, 2, 3). This series, in turn, has strong similarities to the extensively studied polyiodides I2n + 1− (n = 1, 2, 3, 4), where I− replaces Ph3P as the base (Svensson & Kloo, 2003).

Polyiodides are classified according to their I—I bond lengths, e.g. I5− could be described as V-shaped [(I−)·2I2] or L-shaped [(I3−)·(I2)], depending on the pattern of interatomic distances. Furthermore, below 3.3 Å (Coppens, 1982) or, arguably, 3.4 Å (Svensson & Kloo, 2003), the bonds are considered to be intramolecular or primary bonds. Above these values up to 3.7 Å, the bonds are defined as intermolecular or secondary and up to 3.9 Å as weak van der Waals interactions. The same rationale can be used to classify iodophosphonium polyiodide structures, with the proviso that P—I bonds are always primary. Alternatively, a more inclusive scheme based on bond order can easily be set up using empirical bond length versus bond order (n) relationships.

An existing equation, I—I = 2.67 − 0.85log(n) (Burgi, 1975), allows the above bond-length ranges to be converted into bond orders, primary above 0.18 (or 0.14) and secondary down to 0.06. Also, as the crystal structures of several R3PI2 adducts are now known, a similar equation, P—I = 2.35 − 1.14log(n), can be derived for P—I bonds by assuming nI—P = 1 − nI—I (Fig. 2). The following bond orders, calculated by applying these equations to crystallographically determined bond lengths from the Ph3P(I2)n series (Fig. 3), clearly justify the assignment of Ph3PI2 and (Ph3PI)I3 to compounds (1) and (2), respectively. Also, based on these values, (Ph3PI)I5 is the most appropriate description of (3).

Further support for these assignments comes from solution work carried out in dichloroethane, where I3− and I5− ions were detected but not I− (Deplano et al., 1997). These iodophosphonium polyiodide structures are analogous to known polyiodide types; (1) corresponds to a typical asymmetric I3−, (2a) to an L-shaped [(I3−)·I2] and (3) to pyramidal [(I5−)·I2]. In each case, the P—I moiety behaves like a low acidity, but by no means inert, I2. More detailed examination of (3) shows that the I5− part is nearly V-shaped, i.e. [(I−)·2I2], and, as the bond order of the intermolecular bond is close to an intramolecular value, it is worth noting that (3) is bordering on (Ph3PI)(I2)2I cf. [(I−)(I2)3].

The close parallels between the iodophosphonium polyiodides and polyiodides extend to their secondary interactions. Compound (2a) associates into a trans-chain, one of the common contact geometries for pentaiodides (Svensson & Kloo, 2003), by head-to-tail linking of adjacent I3− groups via a 3.741 (1) Å (n = 0.05) secondary bond. A stronger secondary bond of 3.601 (1) Å (n = 0.08) links (3) into a cis-chain (Fig. 4), which can be pictured as evolving from the trans-chain by adding an extra I2 side branch opposite the IPPh3 moiety and then twisting the chain from trans to cis. This type of extended structure is also seen in the heptaiodide [H3O.18-crown-6]I7, where it has been described as a sawhorse (Abd El Khalik et al., 1999; Junk et al., 1995).

The current, solvent-free, work has broadened our understanding of iodophosphonium polyiodides and, perhaps more importantly, established clear parallels between the Ph3P(I2)n and I2n+1− structures, suggesting that crystals with even higher iodine loadings may well be attainable. Despite the cursory nature of our observations on the melt associated with the formation of (3), there is sufficient evidence to suggest that research along the lines of that carried out on polyiodide melts (Bengtsson et al., 1991) may well prove fruitful in this case too.

Experimental top

The title compound was prepared by placing powdered Ph3P in a 0.7 mm diameter special glass X-ray sample tube to a depth of ca 10 mm, using a second tube as a funnel to prevent the glass becoming contaminated. Approximately the same quantity of fine I2 crystals was added immediately prior to the tube being evacuated with a rotary pump and flame sealed. Although a narrow brown layer appeared instantaneously at the interface between the two materials, it did not develop further until the tube was heated to the melting point of Ph3P. At this point, the I2 crystals and their violet vapour disappeared, to be replaced by a black melt which extended for several mm over the interface region. On cooling, red crystals of Ph3PI(I5), (3), were recovered by breaking the glass tube under inert oil.

Refinement top

As the melt-grown crystals formed as a fused mass, it proved difficult to select an ideal crystal. Despite this, a reasonable quality data set was obtained, enabling the structure to be solved and subsequently refined in spacegroup P1 (No. 2). Some peaks as high as 2.2 e Å−3 remained in the difference Fourier map. These peaks shared y and z coordiates with I atoms but were shifted in the x direction. Since a twinned refinement did not affect the size of the extra peaks or improve the R factors, a twinned model was rejected. It is suggested that stacking faults may occur along the a axis, which coincides with the backbone of the sawhorse.

H atoms were constrained to chemically reasonable positions, with C—H = 0.95 Å and with Uiso(H) = 1.2Ueq(C).

Computing details top

Data collection: COLLECT (Nonius, 1998); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: SCALEPACK and DENZO (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. The molecular structure of (Ph3PI)I5, (3), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
[Figure 2] Fig. 2. The variation of P—I bond length (Å) with bond order n. (I) is (2-Me-1,2-C2B10H10)(iPr)2PI2 (Teixidor et al., 2000), (II) is Ph3PI2 (Godfrey et al., 1991), (III) is (C6H2(OMe)3)3PI2·CH2Cl2 (Godfrey et al., 1998), (IV) is (tBu)3PI2 (DuMont et al., 1987), (V)is (iPr)3PI2·CH2Cl2 (Ruthe et al., 2000) and (VI) is PhMe2PI2 (Bricklebank et al., 1995).
[Figure 3] Fig. 3. Empirically derived bond orders for Ph3P(I2)n (n = 1, 2, 3).
[Figure 4] Fig. 4. The sawhorse structure of (3), formed through association of pyramidal Ph3PI(I5) units via secondary bonds.
iodotriphenylphosphonium pentaiodide top
Crystal data top
C18H15IP+·I5−Z = 2
Mr = 1023.67F(000) = 912
Triclinic, P1Dx = 2.661 Mg m−3
Hall symbol: -P1Mo Kα radiation, λ = 0.71073 Å
a = 9.4288 (3) ÅCell parameters from 5574 reflections
b = 11.7262 (4) Åθ = 1.0–27.5°
c = 12.1270 (5) ŵ = 7.36 mm−1
α = 86.196 (1)°T = 150 K
β = 77.290 (1)°Block, dark red
γ = 77.697 (1)°0.1 × 0.1 × 0.05 mm
V = 1277.66 (8) Å3
Data collection top
Nonius KappaCCD area-detector
diffractometer		3809 reflections with I > 2σ(I)
CCD rotation images, thick slices scansRint = 0.067
Absorption correction: multi-scan
(Blessing, 1995, 1997)		θmax = 26.5°, θmin = 3.2°
Tmin = 0.478, Tmax = 0.683h = 0→11
5574 measured reflectionsk = −14→14
5262 independent reflectionsl = −14→15
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.053 w = 1/[σ2(Fo2) + (0.0677P)2 + 14.7624P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.146(Δ/σ)max = 0.001
S = 1.07Δρmax = 2.20 e Å−3
5262 reflectionsΔρmin = −1.42 e Å−3
226 parameters
Crystal data top
C18H15IP+·I5−γ = 77.697 (1)°
Mr = 1023.67V = 1277.66 (8) Å3
Triclinic, P1Z = 2
a = 9.4288 (3) ÅMo Kα radiation
b = 11.7262 (4) ŵ = 7.36 mm−1
c = 12.1270 (5) ÅT = 150 K
α = 86.196 (1)°0.1 × 0.1 × 0.05 mm
β = 77.290 (1)°
Data collection top
Nonius KappaCCD area-detector
diffractometer		5262 independent reflections
Absorption correction: multi-scan
(Blessing, 1995, 1997)		3809 reflections with I > 2σ(I)
Tmin = 0.478, Tmax = 0.683Rint = 0.067
5574 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0530 restraints
wR(F2) = 0.146H-atom parameters constrained
S = 1.07 w = 1/[σ2(Fo2) + (0.0677P)2 + 14.7624P]
where P = (Fo2 + 2Fc2)/3
5262 reflectionsΔρmax = 2.20 e Å−3
226 parametersΔρmin = −1.42 e Å−3
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C10.5118 (11)0.5275 (8)0.7322 (9)0.030 (2)
C20.6277 (12)0.4631 (9)0.6519 (9)0.035 (2)
H20.64720.48910.57520.042*
C30.7132 (14)0.3606 (9)0.6872 (10)0.048 (3)
H30.79080.31550.63410.058*
C40.6851 (13)0.3247 (9)0.7987 (10)0.040 (3)
H40.74790.25740.82250.049*
C50.5683 (14)0.3839 (10)0.8764 (10)0.046 (3)
H50.54750.35420.95180.055*
C60.4810 (12)0.4860 (9)0.8459 (8)0.034 (2)
H60.40170.5280.90010.041*
C70.3434 (12)0.7574 (8)0.8113 (8)0.032 (2)
C80.4535 (13)0.8009 (9)0.8447 (9)0.038 (2)
H80.55370.77920.8050.046*
C90.4188 (15)0.8752 (9)0.9347 (10)0.043 (3)
H90.49450.90440.95710.052*
C100.2747 (15)0.9061 (9)0.9912 (9)0.044 (3)
H100.2510.95751.0530.053*
C110.1615 (14)0.8644 (9)0.9607 (10)0.042 (3)
H110.06140.88681.00050.05*
C120.1980 (12)0.7904 (10)0.8718 (9)0.037 (2)
H120.12190.76050.85080.045*
C130.2329 (12)0.6291 (9)0.6593 (10)0.038 (2)
C140.2013 (14)0.5180 (10)0.6779 (10)0.043 (3)
H140.2690.45570.70410.052*
C150.0699 (14)0.5005 (11)0.6574 (10)0.047 (3)
H150.04510.42580.67270.056*
C16−0.0274 (13)0.5897 (11)0.6148 (9)0.043 (3)
H16−0.11750.57530.60130.052*
C170.0054 (13)0.6973 (12)0.5924 (10)0.048 (3)
H17−0.06080.75750.56210.058*
C180.1375 (13)0.7196 (10)0.6141 (9)0.042 (3)
H180.16150.79450.59850.05*
P0.3958 (3)0.6592 (2)0.6956 (2)0.0306 (6)
I10.53184 (8)0.75303 (6)0.53625 (6)0.03577 (19)
I20.69741 (8)0.91789 (7)0.32394 (6)0.0403 (2)
I30.76958 (8)0.76348 (7)0.11275 (7)0.0452 (2)
I40.83547 (11)0.62586 (9)−0.07820 (8)0.0635 (3)
I51.02136 (8)0.95303 (6)0.32387 (6)0.03562 (19)
I61.30684 (9)0.97919 (7)0.32291 (7)0.0461 (2)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.034 (5)0.014 (4)0.038 (6)−0.004 (4)−0.004 (4)−0.002 (4)
C20.038 (6)0.033 (6)0.027 (5)0.009 (4)−0.005 (4)0.000 (4)
C30.058 (8)0.024 (5)0.045 (7)0.003 (5)0.015 (6)−0.007 (5)
C40.043 (7)0.029 (6)0.042 (6)0.003 (5)−0.003 (5)−0.003 (5)
C50.059 (8)0.040 (6)0.035 (6)−0.003 (5)−0.007 (5)−0.003 (5)
C60.039 (6)0.035 (6)0.024 (5)−0.005 (4)−0.002 (4)−0.003 (4)
C70.046 (6)0.022 (5)0.026 (5)−0.009 (4)−0.004 (4)0.000 (4)
C80.041 (6)0.032 (6)0.039 (6)−0.002 (5)−0.007 (5)−0.002 (4)
C90.066 (8)0.029 (6)0.041 (6)−0.018 (5)−0.017 (6)0.002 (5)
C100.077 (9)0.029 (6)0.026 (5)−0.011 (5)−0.007 (6)0.000 (4)
C110.047 (7)0.035 (6)0.044 (6)−0.014 (5)−0.003 (5)−0.008 (5)
C120.032 (6)0.043 (6)0.035 (6)−0.003 (5)−0.009 (5)0.005 (5)
C130.039 (6)0.034 (6)0.042 (6)−0.006 (5)−0.009 (5)−0.003 (5)
C140.052 (7)0.044 (7)0.041 (6)−0.016 (5)−0.018 (5)0.005 (5)
C150.052 (7)0.042 (7)0.052 (7)−0.012 (5)−0.017 (6)−0.008 (5)
C160.041 (7)0.054 (8)0.036 (6)−0.009 (5)−0.010 (5)−0.013 (5)
C170.036 (6)0.065 (8)0.039 (6)0.011 (6)−0.016 (5)−0.015 (6)
C180.049 (7)0.038 (6)0.028 (5)−0.003 (5)0.005 (5)0.001 (4)
P0.0350 (14)0.0272 (13)0.0273 (13)−0.0080 (10)−0.0015 (11)0.0029 (10)
I10.0407 (4)0.0330 (4)0.0324 (4)−0.0094 (3)−0.0045 (3)0.0035 (3)
I20.0323 (4)0.0476 (4)0.0419 (4)−0.0136 (3)−0.0075 (3)0.0088 (3)
I30.0406 (4)0.0468 (5)0.0485 (5)−0.0136 (3)−0.0092 (3)0.0117 (3)
I40.0515 (5)0.0800 (7)0.0565 (5)−0.0130 (4)−0.0037 (4)−0.0110 (5)
I50.0351 (4)0.0320 (4)0.0386 (4)−0.0038 (3)−0.0082 (3)−0.0002 (3)
I60.0414 (4)0.0501 (5)0.0526 (5)−0.0170 (3)−0.0154 (4)0.0020 (3)
Geometric parameters (Å, º) top
C1—C21.410 (14)C10—H100.95
C1—C61.420 (14)C11—C121.366 (16)
C1—P1.784 (10)C11—H110.95
C2—C31.396 (15)C12—H120.95
C2—H20.95C13—C141.391 (16)
C3—C41.375 (16)C13—C181.402 (16)
C3—H30.95C13—P1.797 (12)
C4—C51.374 (16)C14—C151.375 (17)
C4—H40.95C14—H140.95
C5—C61.380 (16)C15—C161.389 (17)
C5—H50.95C15—H150.95
C6—H60.95C16—C171.359 (18)
C7—C121.392 (15)C16—H160.95
C7—C81.393 (16)C17—C181.408 (17)
C7—P1.790 (10)C17—H170.95
C8—C91.380 (15)C18—H180.95
C8—H80.95P—I12.412 (3)
C9—C101.365 (18)I2—I33.1022 (11)
C9—H90.95I3—I42.7906 (13)
C10—C111.392 (17)I5—I62.7709 (10)
C2—C1—C6120.1 (9)C12—C11—H11120.9
C2—C1—P122.3 (8)C10—C11—H11120.9
C6—C1—P117.7 (7)C11—C12—C7122.0 (11)
C3—C2—C1118.8 (9)C11—C12—H12119
C3—C2—H2120.6C7—C12—H12119
C1—C2—H2120.6C14—C13—C18120.9 (11)
C4—C3—C2120.1 (10)C14—C13—P120.1 (9)
C4—C3—H3120C18—C13—P119.1 (9)
C2—C3—H3120C15—C14—C13118.5 (11)
C5—C4—C3121.6 (11)C15—C14—H14120.8
C5—C4—H4119.2C13—C14—H14120.8
C3—C4—H4119.2C14—C15—C16121.4 (11)
C4—C5—C6120.5 (11)C14—C15—H15119.3
C4—C5—H5119.7C16—C15—H15119.3
C6—C5—H5119.7C17—C16—C15120.4 (11)
C5—C6—C1118.9 (10)C17—C16—H16119.8
C5—C6—H6120.6C15—C16—H16119.8
C1—C6—H6120.6C16—C17—C18120.0 (11)
C12—C7—C8118.0 (10)C16—C17—H17120
C12—C7—P123.2 (9)C18—C17—H17120
C8—C7—P118.7 (8)C13—C18—C17118.7 (11)
C9—C8—C7120.8 (11)C13—C18—H18120.6
C9—C8—H8119.6C17—C18—H18120.6
C7—C8—H8119.6C1—P—C7109.9 (5)
C10—C9—C8119.3 (11)C1—P—C13110.6 (5)
C10—C9—H9120.4C7—P—C13109.9 (5)
C8—C9—H9120.4C1—P—I1109.4 (3)
C9—C10—C11121.7 (11)C7—P—I1107.8 (3)
C9—C10—H10119.2C13—P—I1109.2 (4)
C11—C10—H10119.2I4—I3—I2179.57 (4)
C12—C11—C10118.2 (11)
C6—C1—C2—C3−1.8 (17)C14—C13—C18—C172.7 (16)
P—C1—C2—C3−179.7 (9)P—C13—C18—C17−176.1 (8)
C1—C2—C3—C4−0.9 (19)C16—C17—C18—C13−0.2 (16)
C2—C3—C4—C54 (2)C2—C1—P—C7−146.3 (9)
C3—C4—C5—C6−4 (2)C6—C1—P—C735.7 (10)
C4—C5—C6—C11.5 (18)C2—C1—P—C1392.1 (10)
C2—C1—C6—C51.5 (16)C6—C1—P—C13−85.9 (9)
P—C1—C6—C5179.5 (9)C2—C1—P—I1−28.2 (10)
C12—C7—C8—C9−0.4 (15)C6—C1—P—I1153.8 (7)
P—C7—C8—C9−178.8 (8)C12—C7—P—C1−113.8 (9)
C7—C8—C9—C10−0.1 (16)C8—C7—P—C164.5 (9)
C8—C9—C10—C110.2 (17)C12—C7—P—C138.2 (10)
C9—C10—C11—C120.2 (17)C8—C7—P—C13−173.5 (8)
C10—C11—C12—C7−0.8 (17)C12—C7—P—I1127.1 (8)
C8—C7—C12—C110.9 (16)C8—C7—P—I1−54.7 (9)
P—C7—C12—C11179.2 (9)C14—C13—P—C19.2 (11)
C18—C13—C14—C15−3.9 (17)C18—C13—P—C1−171.9 (8)
P—C13—C14—C15175.0 (9)C14—C13—P—C7−112.3 (10)
C13—C14—C15—C162.6 (18)C18—C13—P—C766.6 (10)
C14—C15—C16—C17−0.1 (18)C14—C13—P—I1129.7 (9)
C15—C16—C17—C18−1.1 (17)C18—C13—P—I1−51.4 (9)

Experimental details

Crystal data
Chemical formulaC18H15IP+·I5−
Mr1023.67
Crystal system, space groupTriclinic, P1
Temperature (K)150
a, b, c (Å)9.4288 (3), 11.7262 (4), 12.1270 (5)
α, β, γ (°)86.196 (1), 77.290 (1), 77.697 (1)
V (Å3)1277.66 (8)
Z2
Radiation typeMo Kα
µ (mm−1)7.36
Crystal size (mm)0.1 × 0.1 × 0.05
Data collection
DiffractometerNonius KappaCCD area-detector
diffractometer
Absorption correctionMulti-scan
(Blessing, 1995, 1997)
Tmin, Tmax0.478, 0.683
No. of measured, independent and
observed [I > 2σ(I)] reflections		5574, 5262, 3809
Rint0.067
(sin θ/λ)max (Å−1)0.628
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.053, 0.146, 1.07
No. of reflections5262
No. of parameters226
H-atom treatmentH-atom parameters constrained
w = 1/[σ2(Fo2) + (0.0677P)2 + 14.7624P]
where P = (Fo2 + 2Fc2)/3
Δρmax, Δρmin (e Å−3)2.20, −1.42

Computer programs: COLLECT (Nonius, 1998), SCALEPACK (Otwinowski & Minor, 1997), SCALEPACK and DENZO (Otwinowski & Minor, 1997), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).

Selected geometric parameters (Å, º) top
C1—P1.784 (10)I2—I33.1022 (11)
C7—P1.790 (10)I3—I42.7906 (13)
C13—P1.797 (12)I5—I62.7709 (10)
P—I12.412 (3)
C1—P—C7109.9 (5)C7—P—I1107.8 (3)
C1—P—C13110.6 (5)C13—P—I1109.2 (4)
C7—P—C13109.9 (5)I4—I3—I2179.57 (4)
C1—P—I1109.4 (3)
C2—C1—P—I1−28.2 (10)C14—C13—P—I1129.7 (9)
C8—C7—P—I1−54.7 (9)
 

Acknowledgements

The authors acknowledge the use of the EPSRC Chemical Database Service at Daresbury (Fletcher et al., 1996; Allen et al., 1983[Allen, F. H., Kennard, O. & Taylor, R. (1983). Acc. Chem. Res. 16, 146-153.][Fletcher, D. A., McMeeking, R. F. & Parkin, D. (1996). J. Chem. Inf. Comput. Sci. 36, 746-749.]) and EPSRC support for the purchase of equipment.

References

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Journal logoSTRUCTURAL
CHEMISTRY
ISSN: 2053-2296
Volume 62| Part 11| November 2006| Pages o656-o658
doi:10.1107/S0108270106039825
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