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The title compound, C4H12N+·I5-, consists of V-shaped I5- ions which are linked to adjacent I5- ions to form a flat square mesh normal to (001), with four I atoms on each edge. The tetra­methyl­ammonium ions are located at the centre of each square.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801004536/bt6024sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536801004536/bt6024Isup2.hkl
Contains datablock I

CCDC reference: 162822

Key indicators

  • Single-crystal X-ray study
  • T = 296 K
  • Mean [sigma](I-I) = 0.001 Å
  • Some non-H atoms missing
  • R factor = 0.052
  • wR factor = 0.143
  • Data-to-parameter ratio = 45.5

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


Red Alert Alert Level A:
ABSTM_02 Alert A Crystal and compound unsuitable for non-numerical corrections. Product of mu and tmid > 3.0 Value of mu given = 10.173 tmid = 0.500 CHEMS_01 Alert A The sum formula contains more than one moiety.
Amber Alert Alert Level B:
CHEMS_01 Alert B The sum formula contains an invalid character. WARNING - The character , is not allowed in the _chemical_formula_sum
Yellow Alert Alert Level C:
REFLT_03 From the CIF: _diffrn_reflns_theta_max 30.87 From the CIF: _reflns_number_total 2182 TEST2: Reflns within _diffrn_reflns_theta_max Count of symmetry unique reflns 2416 Completeness (_total/calc) 90.31% Alert C: < 95% complete General Notes
CELLZ_01 From the CIF: _cell_formula_units_Z 4 From the CIF: _chemical_formula_sum C4 H12 N, I5 TEST: Compare cell contents of formula and atom_site data WARNING: Unexpected atom type is in site list: N WARNING: Formula and atom_type_symbol element names mismatch. atom Z*formula cif sites diff C 16.00 16.00 0.00 H 48.00 48.00 0.00 N, 4.00 0.00 4.00 I 20.00 20.00 0.00 WARNING: Site labels do not match formula elements Difference between formula and atom_site contents detected. ALERT: Large difference may be due to a symmetry error - see SYMMG tests
2 Alert Level A = Potentially serious problem
1 Alert Level B = Potential problem
1 Alert Level C = Please check

Comment top

Various polyiodide ions are known, with the most frequently reported being I3- and I5- (Kloo et al., 2000; Blake et al., 1998). The structures of a number of tetraorganoammonium salts of I5- are in the Cambridge Structural Database (CSD; Allen & Kennard, 1993) at the Chemical database service of the EPSRC (Fletcher et al., 1996), including those of [EtMePh2N]I5 (213550, refcode FIQLAS; Tebbe & Loukili, 1999), {2[Me2Ph2N][I5]2.I2} (161933, ZIVXOR; Tebbe & Gilles, 1996a) [EtMe3N]I5 (Loukili & Tebbe, 1999), [PriMe2PhN]I5.I2 (195990, PAZQEM; Tebbe & Loukili, 1998), [Pr4N]I5 (Tebbe & Gilles, 1996b) and [Me4N]I5 (130287, DULZOZ; Tsvetkov et al., 1986). However, only the data for cell dimensions and space group are provided for [Me4N]I5 in the CSD. The structure of [Me4N]I5 had also featured in earlier studies (Broekema et al., 1959; Hach & Rundle, 1951), while a listing of cell dimensions and the space group for [Me4N]I5, with a reference to a dissertation (Loukili, 1998), were provided by Loukili & Tebbe (1999).

Tetraorganoammonium polyiodides are generally prepared from [R4N]I and the requisite number of molar equivalents of iodine in solvents such as methanol. Tetramethylammonium pentaiodide was isolated in this study from aqueous solutions of [Me4N]I and SnI2 (equimolar) in water, the co-product being yellow–brown hydrated tin(IV) oxide. Similar reactions between [Me4N]X and SnX2 (X = Cl or Br) in contrast simply led to [Me4N][SnX3].

The refinement of the carbon displacement parameters for the tetramethylammonium ion gave very high values, suggesting disorder. This was modelled using two superimposed orientations of the molecule via the SHELX PART instruction. The C atoms could not be refined anisotropically, but the final ratio of the two orientations was 85:15. However, the R value was not improved (5.75% compared to 5.14% for the ordered model) and thus the ordered model has been retained for this report.

The structure of the title compound (Fig. 1) consists of isolated tetramethylammonium ions and I5- ions. The I5 units are linked via longer I—I bonds to form a square mesh normal to (001) (Fig. 2), with I1 coordinated to two I2 atoms at 3.1514 (8) Å and two I3 at 3.6453 (9) Å [symmetry codes: (i) 0.5 - x, y + 0.5, 0.5 - z; (ii) x - 0.5, y + 0.5, z], which are within the van der Waals radius sum of 3.96 Å. The tetramethylammonium ions are located at the centre of each square.

This square mesh is similar to that found in (EtMe3N)I5 (Loukili & Tebbe, 1999); however, in this case, the mesh is flat and parallel to [010], whereas in (EtMe3N)I5 there is significant puckering, likely caused by the relative location of the cation. These are the only such square-mesh formations to be reported to date; other pentaiodide networks form herring-bone, F-shaped and linear conformations, and in a few cases isolated I5- anions.

Many pentaiodides are reported in the literature. In addition, pentaiodide ions may form as part of a more complex polyiodide framework. This is clearly seen in the work of Tebbe and co-workers, in which the V angle varies from 83.51° in (EtMe3N)I5 (Loukili & Tebbe, 1999) to 119.60° in bipyridinium heptaiodide, (C10H9N2)I7 (Tebbe & Bittner, 1995), whereas the `straight limb' angle varies from 172.09° in (Me2Ph2N)3I13 (Tebbe & Gilles, 1996a) to 179.57° in (UrEt)2I8 (Grafe-Kavoosian et al., 1998). Bond lengths in the V motif can be divided into the outer (shorter) and inner (longer). The outer bond lengths range from 2.739 to 2.873 Å, wheras the inner range from 2.975 to 3.460 Å. There is, evidently, a significant (0.1 Å) gap between these values which supports the alternative description of the pentaiodide unit as [2(I2).I]-.

Experimental top

An equimolar solution of NMe4I and SnI2 in water was maintained at 368 K for 2 h with stirring. The initial orange-coloured solution initially produced a near-black coloured precipitate which slowly redissolved to be replaced by a pale-yellow precipitate. The reaction mixture was filtered and green–black crystals of the title compound were deposited from the filtrate on standing. M.p. 398–400 K: literature value 399–400 K (Gama & Filguieras, 1989). Analysis: C 6.68, H 1.99, N 1.83%; calculated for C4H12I5N: C 6.78, H 1.71, N 1.98%.

Refinement top

The maximum residual electron density was 1.48 e Å-3 at 0.89 Å from I3; all residuals >0.8 e Å-3 were within 1 Å of I atoms.

Computing details top

Data collection: SMART (Bruker, 1999); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT; program(s) used to solve structure: SHELXS86 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ATOMS (Dowty, 1999) and ORTEP-3 (Farrugia, 1999); software used to prepare material for publication: CIFTAB (Sheldrick, 1997).

Figures top
[Figure 1] Fig. 1. The title compound with the atomic numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. H atoms have been omitted for clarity. [Symmetry code: (i) -x, y, -z + 1/2.]
[Figure 2] Fig. 2. View normal to (001) showing the pentaiodine mesh and the location of the tetramethylammonium ions.
Tetramethylammonium pentaiodide top
Crystal data top
C4H12N+·I5F(000) = 1232
Mr = 708.64Dx = 3.092 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
a = 13.311 (1) ÅCell parameters from 2244 reflections
b = 13.5395 (11) Åθ = 2.4–29.4°
c = 8.8727 (7) ŵ = 10.17 mm1
β = 107.801 (2)°T = 296 K
V = 1522.5 (2) Å3Prism, dark purple
Z = 40.60 × 0.50 × 0.50 mm
Data collection top
Bruker SMART 1000 Area CCD
diffractometer
2182 independent reflections
Radiation source: fine-focus sealed tube1622 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.032
ϕω scansθmax = 30.9°, θmin = 2.2°
Absorption correction: multi-scan
(SADABS; Bruker, 1999)
h = 1018
Tmin = 0.742, Tmax = 0.906k = 1818
4712 measured reflectionsl = 1211
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.052H-atom parameters constrained
wR(F2) = 0.143 w = 1/[σ2(Fo2) + (0.074P)2 + 6.1215P]
where P = (Fo2 + 2Fc2)/3
S = 1.05(Δ/σ)max < 0.001
2182 reflectionsΔρmax = 1.48 e Å3
48 parametersΔρmin = 1.47 e Å3
0 restraintsExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: heavy-atom methodExtinction coefficient: 0.00143 (18)
Crystal data top
C4H12N+·I5V = 1522.5 (2) Å3
Mr = 708.64Z = 4
Monoclinic, C2/cMo Kα radiation
a = 13.311 (1) ŵ = 10.17 mm1
b = 13.5395 (11) ÅT = 296 K
c = 8.8727 (7) Å0.60 × 0.50 × 0.50 mm
β = 107.801 (2)°
Data collection top
Bruker SMART 1000 Area CCD
diffractometer
2182 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 1999)
1622 reflections with I > 2σ(I)
Tmin = 0.742, Tmax = 0.906Rint = 0.032
4712 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0520 restraints
wR(F2) = 0.143H-atom parameters constrained
S = 1.05Δρmax = 1.48 e Å3
2182 reflectionsΔρmin = 1.47 e Å3
48 parameters
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.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Also note that for data up to theta max, the completeness is only 90%. Usually ACTA n would have been used to check the >99% completeness, but in this case with the C-centred cell, ACTA 50 gives meaningless (<50%) completeness values (commented out at the bottom of this file). In addition, several frames of data (approx. 10 in 1500) were lost. However a check with PLATON showed that the data are >99% complete at 27.5 °.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
I10.00000.17657 (6)0.25000.0682 (3)
I20.16060 (4)0.01915 (4)0.19877 (6)0.0605 (2)
I30.30588 (5)0.12546 (5)0.18005 (8)0.0750 (3)
N10.00000.6882 (8)0.25000.075 (3)
C10.032 (2)0.6330 (18)0.135 (2)0.210 (14)
H1A0.02770.59800.06730.316*
H1B0.08590.58680.18720.316*
H1C0.05890.67740.07180.316*
C20.084 (3)0.748 (3)0.333 (4)0.33 (3)
H2A0.14270.73870.29300.494*
H2B0.10500.73160.44360.494*
H2C0.06260.81640.32010.494*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
I10.0614 (5)0.0515 (4)0.1039 (7)0.0000.0432 (4)0.000
I20.0564 (3)0.0629 (4)0.0645 (4)0.0039 (2)0.0222 (2)0.0007 (2)
I30.0687 (4)0.0790 (5)0.0831 (5)0.0114 (3)0.0316 (3)0.0031 (3)
N10.088 (8)0.059 (6)0.091 (8)0.0000.045 (6)0.000
C10.31 (3)0.20 (2)0.152 (17)0.15 (2)0.12 (2)0.017 (16)
C20.38 (5)0.35 (5)0.33 (5)0.26 (5)0.21 (4)0.11 (4)
Geometric parameters (Å, º) top
I1—I23.1485 (8)C1—H1A0.9600
I1—I2i3.1486 (8)C1—H1B0.9600
I2—I32.7923 (8)C1—H1C0.9600
N1—C2i1.40 (3)C2—H2A0.9600
N1—C21.40 (3)C2—H2B0.9600
N1—C11.433 (17)C2—H2C0.9600
N1—C1i1.433 (17)
I2—I1—I2i94.79 (3)H1A—C1—H1B109.5
I3—I2—I1175.11 (2)N1—C1—H1C109.5
C2i—N1—C2109 (3)H1A—C1—H1C109.5
C2i—N1—C1106.9 (16)H1B—C1—H1C109.5
C2—N1—C1108.5 (16)N1—C2—H2A109.5
C2i—N1—C1i108.5 (16)N1—C2—H2B109.5
C2—N1—C1i106.9 (16)H2A—C2—H2B109.5
C1—N1—C1i117 (2)N1—C2—H2C109.5
N1—C1—H1A109.5H2A—C2—H2C109.5
N1—C1—H1B109.5H2B—C2—H2C109.5
Symmetry code: (i) x, y, z+1/2.

Experimental details

Crystal data
Chemical formulaC4H12N+·I5
Mr708.64
Crystal system, space groupMonoclinic, C2/c
Temperature (K)296
a, b, c (Å)13.311 (1), 13.5395 (11), 8.8727 (7)
β (°) 107.801 (2)
V3)1522.5 (2)
Z4
Radiation typeMo Kα
µ (mm1)10.17
Crystal size (mm)0.60 × 0.50 × 0.50
Data collection
DiffractometerBruker SMART 1000 Area CCD
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 1999)
Tmin, Tmax0.742, 0.906
No. of measured, independent and
observed [I > 2σ(I)] reflections
4712, 2182, 1622
Rint0.032
(sin θ/λ)max1)0.722
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.052, 0.143, 1.05
No. of reflections2182
No. of parameters48
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)1.48, 1.47

Computer programs: SMART (Bruker, 1999), SAINT (Bruker, 1999), SAINT, SHELXS86 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), ATOMS (Dowty, 1999) and ORTEP-3 (Farrugia, 1999), CIFTAB (Sheldrick, 1997).

 

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