## metal-organic compounds

 IUCrDATA
ISSN: 2414-3146

## trans-Carbonyl­chlorido­bis­­(tri­ethyl­phosphane-κP)platinum(II) tetra­fluorido­borate

aDepartment of Chemistry, Fordham University, 441 East Fordham Road, Bronx, NY 10458, USA
*Correspondence e-mail: pcorfield@fordham.edu

(Received 30 May 2022; accepted 8 June 2022; online 10 June 2022)

The chemical formulation of the title compound was established as trans-[PtCl{P(C2H5)3(CO)}BF4 by single-crystal X-ray analysis, in contrast to the five-coordinate tetra­fluoro­ethyl­ene complex that had been anti­cipated. The compound had been prepared by reaction of trans-PtHCl(P(C2H5)3)2 with C2F4 in the absence of air, and the presence of the carbonyl group was not suspected. The square-planar cations and BF4 anions are linked by C—H⋯F and C—H⋯O inter­actions into thick wavy (010) sheets. The present crystal-structure refinement is based on the original intensity data recorded in 1967.

Chemical scheme

### Structure description

A low-yield product in the reaction of trans-PtHCl(P(C2H5)3)2 with C2F4 in the absence of air was originally postulated to be a five-coordinate platinum complex, PtHCl(π-C2F4)(P(C2H5)3)2 (Clark & Tsang, 1967), and the crystal-structure determination was undertaken at that time in view of the then current inter­est in five-coordination and of π-complexes. As described in Clark et al. (1967), the preliminary crystal-structure model showed no evidence of five-coordination, nor of the presence of a π-bonded tetra­fluoro­ethyl­ene group. Instead, a four-coordinated, cationic PtII complex was indicated, with a carbonyl group as the fourth ligand, isoelectronic with Vaska's compound, IrCl(CO)(PR3)2 (Vaska & DiLuzio, 1961). The presence of a carbonyl group was completely unexpected, as the reaction had been carried out in a vacuum line, in the absence of oxygen. This was the first reported mol­ecular structure of a platinum carbonyl at the time, according to our database analysis below. The strong carbonyl vibrational band in the infrared spectrum was mistaken for the anti­cipated Pt—H band. Evidently, the carbonyl oxygen atom had been extracted from the Pyrex glassware by the tetra­fluoro­ethyl­ene reagent. That reaction vessels are not always as inert as they are expected to be is the subject of a recent review by Nielsen & Pedersen (2022) in which formation of the title compound in this paper is one of several examples of fluorine compounds reacting with glassware.

The crystal structure refinement based on the original X-ray intensity data recorded in 1967 is now presented here, because no atomic coordinates were given in the original report (Clark et al., 1967) or deposited with the Cambridge Structural Database (CSD; Groom et al., 2016). The square-planar platinum(II) cation and a tetra­fluorido­borate anion are shown in Fig. 1. As can be seen, the cation has an approximate mirror plane of symmetry that extends to the conformations of the ethyl groups. The Pt—CO bond length is 1.812 (17) Å, Pt—Cl is 2.301 (4) Å, and the Pt—P bond lengths are 2.341 (5) and 2.348 (5) Å. The P—Pt—CO angles average 92.9 (8)° while the Cl—Pt—P angles average 87.2 (2)°. The trans angles P—Pt—P and Cl—Pt—C are 174.10 (17)° and 177.0 (12)°, respectively, with the slight distortions from linearity tending towards a flattened tetra­hedron rather than a flattened square pyramid. Each of the tri­ethyl­phosphine groups has one ethyl group in the trans conformation and two in the gauche conformation.

 Figure 1 View of the mol­ecular entities showing the atomic numbering and displacement ellipsoids at the 50% probability level.

Packing diagrams showing views down the b and c axes are shown in Fig. 2a and 2b. There are close contacts between each tetra­fluorido­borate anion and the ethyl groups of three neighboring cations with putative C—H⋯F hydrogen bonds, as listed in Table 1. The Hirshfeld dnorm plot for the BF4 anion shown in Fig. 3 was produced with CrystalExplorer (Spackman et al., 2021) and indicates a close contact near F2, probably due to the C13—H13⋯F2 hydrogen bond, which seems to be the strongest C—H⋯F bond. The chlorido and carbonyl ligands do not have close inter­molecular contacts, perhaps because they are shielded by the gauche conformations of the neighboring ethyl groups. A putative weak C—H⋯O hydrogen bond is listed in Table 1 and shown in red in Fig. 3. The hydrogen bonds listed join cations and anions into thick wavy (010) sheets, as can be seen in Fig. 2b.

 Table 1Hydrogen-bond geometry (Å, °)
D—H⋯A D—H H⋯A DA D—H⋯A
C5—H5B⋯O1i 0.97 2.75 3.45 (2) 129
C13—H13B⋯F2ii 0.96 2.43 3.27 (3) 147
C4—H4A⋯F2 0.97 2.56 3.48 (3) 159
C7—H7A⋯F4iii 0.97 2.67 3.46 (3) 140
C11—H11B⋯F3 0.96 2.75 3.47 (3) 133
C6—H6A⋯F1ii 0.97 2.81 3.67 (4) 147
Symmetry codes: (i) ; (ii) ; (iii) .
 Figure 2 Projections of the structure down the b axis (a) and c axis (b), with arbitrary sphere sizes for the atoms. The reference cation and anion have Pt and B atoms identified. Putative C—H⋯O and C—H⋯F hydrogen bonds are shown as red and green dashed lines, respectively.
 Figure 3 Hirshfeld dnorm surface for the BF4− anion, showing the red area that indicates close contacts for F2.

Database analysis

From the time the preliminary structure of this compound was published in 1967, crystal and mol­ecular structures of a wide variety of platinum carbonyl complexes have been reported, ranging from metal clusters through monomeric complexes as in this case. All 662 structures found with the PtCO' search fragment in the CSD database, with all filters removed except for single-crystal structure', except the present one (TEPPTC) are dated 1968 or after. All but 20 of these structures have only one CO group coordinating to the PtII atom while the rest have just two coordinating carbonyl groups except for the [Pt(CO)4]2+ cation reported by Willner et al. (2001) in entry QEZTEU. The mean Pt—CO distance for the 603 structures with coordinates given is 1.860 Å, with a wide range of 1.680 to 2.095 Å. It is inter­esting that the presence of phosphine ligands tends to lead to longer Pt—CO distances, while the presence of a Cl ligand to shorter Pt—CO distances. Thus, in the 35 entries in the above structures that have two PR3 groups attached to the PtII atom as well as the CO group, the mean Pt—C distance is 1.910 Å, with a narrow range of 1.855–1.965 Å, while for the 36 entries that have a Cl as well as a carbonyl ligand, the mean Pt—CO distance is 1.837 Å with a range of 1.753 to 1.901 Å. In the latter case, the Pt—CO distance seems insensitive to whether the Cl atom is cis or trans to the CO group. These tendencies must oppose each other in the present structure, leading to the Pt—CO distance of 1.812 (17) Å. Entry GEYBOB (Rusakov et al., 1988) has the same cation as in the present structure, but the anion is BF3Cl and there is a solvent mol­ecule in the crystal. The shape of the cation is very similar to that of the present structure, with similar distortions of the angles from 90° and a Pt—CO bond length of 1.846 Å.

### Synthesis and crystallization

A sample supplied by Dr H. C. Clark had been synthesized as described in Clark & Tsang (1967). Crystals suitable for X-ray analysis were obtained by recrystallization of the sample from methyl acetate.

### Refinement

With the early automatic diffractometer that was used to collect the original X-ray intensity data in 1967, it was not customary to obtain a set of Friedel pairs of reflections in the case of a non-centrosymmetric structure. In this case, however, due to the polar space group and the poor scattering by the small crystal, data were collected over the whole sphere of reflection up to θ = 20°; in addition, data were recollected over four quadrants for the weaker reflections at higher angles. Initial absorption corrections using a Gaussian grid were inconclusive – perhaps due to a programming error –, so for the final refinements an overall absorption correction using the tensor analysis in XABS2 (Parkin et al., 1995) was used. Hydrogen atoms were constrained, with C—H distances of 0.97 Å and 0.96 Å for CH2 and CH3 groups, respectively, and Uiso(H) = 1.5Ueq(C). Anisotropic temperature factors for the carbonyl CO atoms required tight restraints. While the displacement ellipsoids for the fluorine atoms are large, probably indicating some disorder for the BF4 anion (Fig. 1), initial refinements of a disordered model were not successful and the disordered model was not pursued. There is indeed some residual electron density in the neighborhood of the BF4 anion, but only one of the 20 highest electron density peaks in the final difference-Fourier map is near this group. Crystal data, data collection and structure refinement details are summarized in Table 2.

 Table 2Experimental details
 Crystal data Chemical formula [PtCl(C6H15P)2(CO)]BF4 Mr 581.66 Crystal system, space group Orthorhombic, Pca21 Temperature (K) 293 a, b, c (Å) 16.012 (8), 9.171 (4), 14.966 (7) V (Å3) 2197.7 (18) Z 4 Radiation type Mo Kα μ (mm−1) 6.68 Crystal size (mm) 0.12 × 0.10 × 0.08 Data collection Diffractometer Picker, punched card control Absorption correction Empirical (using intensity measurements) (XABS2; Parkin et al., 1995) Tmin, Tmax 0.55, 0.81 No. of measured, independent and observed [I > 2σ(I)] reflections 7773, 3180, 2437 Rint 0.062 (sin θ/λ)max (Å−1) 0.596 Refinement R[F2 > 2σ(F2)], wR(F2), S 0.041, 0.090, 0.92 No. of reflections 3180 No. of parameters 214 No. of restraints 61 H-atom treatment H-atom parameters constrained Δρmax, Δρmin (e Å−3) 0.64, −0.76 Absolute structure Flack x determined using 961 quotients [(I+)−(I−)]/[(I+)+(I−)] (Parsons et al., 2013) Absolute structure parameter 0.000 (14) Computer programs: PICK (local program by J. A. Ibers), PICKOUT (local program by R. J. Doedens) and EQUIV (local program by J. A. Ibers), local version of FORDAP, SHELXL (Sheldrick, 2015), ORTEPIII (Burnett & Johnson, 1996; Farrugia, 2012) and publCIF (Westrip, 2010).

### Structural data

Computing details

Data collection: PICK (local program by J. A. Ibers); cell refinement: PICK (local program by J. A. Ibers); data reduction: PICKOUT (local program by R. J. Doedens) and EQUIV (local program by J. A. Ibers); program(s) used to solve structure: Local version of FORDAP; program(s) used to refine structure: SHELXL (Sheldrick, 2015); molecular graphics: ORTEPIII (Burnett & Johnson, 1996; Farrugia, 2012); software used to prepare material for publication: publCIF (Westrip, 2010).

trans-Carbonylchloridobis(triethylphosphane-κP)platinum(II) tetrafluoridoborate
Crystal data
 [PtCl(C6H15P)2(CO)]BF4 Dx = 1.758 Mg m−3 Dm = 1.734 (4) Mg m−3 Dm measured by flotation in CH3I/CCl4 Mr = 581.66 Mo Kα radiation, λ = 0.7107 Å Orthorhombic, Pca21 Cell parameters from 16 reflections a = 16.012 (8) Å θ = 3.7–14.1° b = 9.171 (4) Å µ = 6.68 mm−1 c = 14.966 (7) Å T = 293 K V = 2197.7 (18) Å3 Needle, colorless Z = 4 0.12 × 0.10 × 0.08 mm F(000) = 1128
Data collection
 Picker, punched card control diffractometer Rint = 0.062 Radiation source: sealed X-ray tube θmax = 25.1°, θmin = 2.2° θ/2θ scans h = 0→19 Absorption correction: empirical (using intensity measurements) (XABS2; Parkin et al., 1995) k = 0→10 Tmin = 0.55, Tmax = 0.81 l = −17→17 7773 measured reflections 3 standard reflections every 250 reflections 3180 independent reflections intensity decay: 8(2) 2437 reflections with I > 2σ(I)
Refinement
 Refinement on F2 Secondary atom site location: difference Fourier map Least-squares matrix: full Hydrogen site location: inferred from neighbouring sites R[F2 > 2σ(F2)] = 0.041 H-atom parameters constrained wR(F2) = 0.090 w = 1/[σ2(Fo2)] where P = (Fo2 + 2Fc2)/3 S = 0.92 (Δ/σ)max = 0.002 3180 reflections Δρmax = 0.64 e Å−3 214 parameters Δρmin = −0.76 e Å−3 61 restraints Absolute structure: Flack x determined using 961 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013) Primary atom site location: heavy-atom method Absolute structure parameter: 0.000 (14)
Special details
 Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)
 x y z Uiso*/Ueq Pt 0.11894 (3) 0.19055 (6) 0.49793 (9) 0.0540 (2) CL 0.0065 (3) 0.0347 (5) 0.5053 (8) 0.0887 (17) P1 0.1894 (3) 0.0057 (5) 0.4207 (4) 0.0580 (13) P2 0.0355 (3) 0.3627 (6) 0.5723 (3) 0.0606 (14) C1 0.2098 (10) 0.3084 (18) 0.497 (3) 0.074 (5) O1 0.2670 (8) 0.3789 (15) 0.498 (2) 0.114 (5) C2 0.1949 (12) −0.1601 (17) 0.4862 (17) 0.068 (5) H2A 0.138889 −0.191260 0.502025 0.102* H2B 0.220505 −0.236749 0.450938 0.102* C3 0.1344 (12) −0.048 (2) 0.3209 (13) 0.081 (6) H3A 0.167832 −0.120101 0.289379 0.122* H3B 0.082483 −0.095089 0.338078 0.122* C4 0.2941 (10) 0.045 (2) 0.3857 (11) 0.061 (5) H4A 0.293095 0.132343 0.349114 0.092* H4B 0.327255 0.066627 0.438343 0.092* C5 −0.0571 (12) 0.405 (2) 0.510 (2) 0.089 (7) H5A −0.087502 0.315295 0.499106 0.133* H5B −0.092341 0.467457 0.545982 0.133* C6 0.0892 (12) 0.5313 (19) 0.5972 (14) 0.071 (6) H6A 0.136834 0.509449 0.634974 0.107* H6B 0.110475 0.571661 0.541807 0.107* C7 −0.0026 (13) 0.295 (2) 0.6757 (12) 0.074 (6) H7A −0.035167 0.370900 0.704742 0.111* H7B −0.039380 0.213328 0.664405 0.111* C8 0.2449 (16) −0.136 (2) 0.5696 (14) 0.100 (8) H8A 0.228595 −0.205293 0.614220 0.150* H8B 0.235030 −0.038809 0.591484 0.150* H8C 0.303262 −0.147316 0.556527 0.150* C9 0.1148 (15) 0.076 (3) 0.2576 (15) 0.117 (9) H9A 0.087111 0.039006 0.205509 0.175* H9B 0.165842 0.123467 0.240124 0.175* H9C 0.079213 0.145449 0.287034 0.175* C10 0.3376 (13) −0.075 (2) 0.3335 (15) 0.095 (7) H10A 0.394947 −0.048653 0.323932 0.143* H10B 0.310361 −0.087509 0.276862 0.143* H10C 0.334969 −0.164404 0.366633 0.143* C11 −0.0435 (15) 0.477 (3) 0.4237 (19) 0.141 (12) H11A −0.093656 0.471759 0.388736 0.212* H11B 0.001072 0.428995 0.392480 0.212* H11C −0.028989 0.577227 0.433552 0.212* C12 0.0369 (16) 0.646 (2) 0.6429 (17) 0.112 (9) H12A 0.069086 0.733174 0.649995 0.167* H12B 0.019712 0.610676 0.700464 0.167* H12C −0.011595 0.666085 0.607203 0.167* C13 0.0687 (15) 0.246 (3) 0.7400 (15) 0.100 (8) H13A 0.046541 0.232547 0.799019 0.150* H13B 0.111629 0.318759 0.741295 0.150* H13C 0.091808 0.155328 0.719096 0.150* B 0.2121 (17) 0.498 (3) 0.272 (2) 0.064 (7) F1 0.259 (3) 0.602 (3) 0.275 (3) 0.287 (18) F2 0.2511 (16) 0.3870 (19) 0.2964 (13) 0.180 (9) F3 0.1531 (14) 0.523 (3) 0.3305 (18) 0.267 (15) F4 0.1865 (18) 0.509 (4) 0.197 (2) 0.278 (16)
Atomic displacement parameters (Å2)
 U11 U22 U33 U12 U13 U23 Pt 0.0466 (3) 0.0576 (3) 0.0578 (3) −0.0066 (3) −0.0007 (10) 0.0042 (9) CL 0.061 (2) 0.076 (3) 0.128 (5) −0.019 (2) 0.008 (6) −0.008 (6) P1 0.051 (3) 0.067 (3) 0.057 (3) −0.003 (3) 0.000 (3) 0.006 (3) P2 0.059 (3) 0.063 (3) 0.060 (3) 0.002 (3) 0.001 (3) 0.018 (3) C1 0.064 (9) 0.070 (10) 0.087 (11) −0.005 (9) 0.030 (18) 0.020 (18) O1 0.090 (9) 0.122 (11) 0.131 (11) −0.045 (9) 0.004 (19) −0.057 (19) C2 0.083 (11) 0.066 (11) 0.055 (13) 0.008 (9) 0.019 (12) 0.030 (12) C3 0.083 (15) 0.083 (14) 0.078 (14) 0.012 (13) −0.037 (12) −0.013 (11) C4 0.049 (11) 0.080 (12) 0.055 (12) −0.007 (10) 0.009 (9) −0.003 (10) C5 0.091 (13) 0.097 (14) 0.079 (18) 0.032 (11) −0.012 (16) 0.022 (16) C6 0.078 (14) 0.059 (12) 0.077 (15) −0.020 (10) 0.034 (11) 0.001 (10) C7 0.084 (13) 0.078 (14) 0.060 (12) 0.015 (12) 0.035 (9) 0.025 (12) C8 0.122 (19) 0.105 (18) 0.072 (14) 0.003 (16) −0.009 (13) 0.035 (13) C9 0.16 (2) 0.106 (18) 0.082 (16) 0.038 (17) −0.057 (16) −0.005 (13) C10 0.099 (17) 0.081 (15) 0.105 (17) 0.021 (13) 0.019 (13) −0.007 (13) C11 0.102 (19) 0.22 (3) 0.102 (19) 0.05 (2) −0.014 (16) 0.08 (2) C12 0.13 (2) 0.077 (16) 0.12 (2) 0.016 (14) 0.062 (17) 0.017 (14) C13 0.110 (17) 0.12 (2) 0.066 (14) 0.001 (16) 0.002 (12) 0.026 (14) B 0.061 (13) 0.044 (13) 0.087 (17) −0.012 (11) −0.011 (13) −0.006 (13) F1 0.37 (4) 0.19 (2) 0.30 (4) −0.11 (3) 0.10 (3) −0.08 (2) F2 0.189 (18) 0.128 (13) 0.22 (2) 0.060 (15) −0.006 (19) 0.034 (14) F3 0.18 (2) 0.38 (4) 0.24 (3) 0.07 (2) 0.123 (19) 0.13 (2) F4 0.25 (3) 0.39 (4) 0.20 (2) 0.14 (3) −0.08 (2) −0.04 (2)
Geometric parameters (Å, º)
 Pt—C1 1.813 (18) C7—C13 1.56 (3) Pt—CL 2.301 (4) C7—H7A 0.9700 Pt—P1 2.341 (5) C7—H7B 0.9700 Pt—P2 2.348 (5) C8—H8A 0.9600 P1—C2 1.812 (17) C8—H8B 0.9600 P1—C3 1.804 (18) C8—H8C 0.9600 P1—C4 1.794 (16) C9—H9A 0.9600 P2—C5 1.80 (2) C9—H9B 0.9600 P2—C6 1.808 (18) C9—H9C 0.9600 P2—C7 1.775 (17) C10—H10A 0.9600 C1—O1 1.120 (17) C10—H10B 0.9600 C2—C8 1.50 (3) C10—H10C 0.9600 C2—H2A 0.9700 C11—H11A 0.9600 C2—H2B 0.9700 C11—H11B 0.9600 C3—C9 1.52 (3) C11—H11C 0.9600 C3—H3A 0.9700 C12—H12A 0.9600 C3—H3B 0.9700 C12—H12B 0.9600 C4—C10 1.52 (2) C12—H12C 0.9600 C4—H4A 0.9700 C13—H13A 0.9600 C4—H4B 0.9700 C13—H13B 0.9600 C5—C11 1.46 (4) C13—H13C 0.9600 C5—H5A 0.9700 B—F1 1.21 (3) C5—H5B 0.9700 B—F2 1.25 (3) C6—C12 1.51 (2) B—F3 1.30 (3) C6—H6A 0.9700 B—F4 1.20 (3) C6—H6B 0.9700 C1—Pt—CL 177.0 (12) C12—C6—H6A 108.5 C1—Pt—P1 92.4 (8) C12—C6—H6B 108.5 C1—Pt—P2 93.3 (8) H6A—C6—H6B 107.5 CL—Pt—P1 87.2 (2) C13—C7—H7A 109.0 CL—Pt—P2 87.1 (2) C13—C7—H7B 109.0 P1—Pt—P2 174.10 (17) H7A—C7—H7B 107.8 O1—C1—Pt 178 (3) C2—C8—H8A 109.5 C2—P1—Pt 111.4 (8) C2—C8—H8B 109.5 C3—P1—Pt 111.9 (7) C2—C8—H8C 109.5 C4—P1—Pt 116.7 (6) H8A—C8—H8B 109.5 C2—P1—C4 106.4 (9) H8A—C8—H8C 109.5 C2—P1—C3 103.9 (11) H8B—C8—H8C 109.5 C3—P1—C4 105.6 (10) C3—C9—H9A 109.5 C5—P2—Pt 111.5 (10) C3—C9—H9B 109.5 C6—P2—Pt 113.7 (6) C3—C9—H9C 109.5 C7—P2—Pt 112.0 (7) H9A—C9—H9B 109.5 C5—P2—C6 108.3 (10) H9A—C9—H9C 109.5 C5—P2—C7 104.3 (12) H9B—C9—H9C 109.5 C6—P2—C7 106.4 (10) C4—C10—H10A 109.5 P1—C2—C8 110.5 (14) C4—C10—H10B 109.5 P1—C3—C9 114.2 (16) C4—C10—H10C 109.5 P1—C4—C10 115.7 (14) H10A—C10—H10B 109.5 P2—C5—C11 115.7 (17) H10A—C10—H10C 109.5 P2—C6—C12 115.1 (14) H10B—C10—H10C 109.5 P2—C7—C13 112.8 (14) C5—C11—H11A 109.5 P1—C2—H2A 109.5 C5—C11—H11B 109.5 P1—C2—H2B 109.5 C5—C11—H11C 109.5 P1—C3—H3A 108.7 H11A—C11—H11B 109.5 P1—C3—H3B 108.7 H11A—C11—H11C 109.5 P1—C4—H4A 108.4 H11B—C11—H11C 109.5 P1—C4—H4B 108.4 C6—C12—H12A 109.5 P2—C5—H5A 108.4 C6—C12—H12B 109.5 P2—C5—H5B 108.4 C6—C12—H12C 109.5 P2—C6—H6A 108.5 H12A—C12—H12B 109.5 P2—C6—H6B 108.5 H12A—C12—H12C 109.5 P2—C7—H7A 109.0 H12B—C12—H12C 109.5 P2—C7—H7B 109.0 C7—C13—H13A 109.5 C8—C2—H2A 109.5 C7—C13—H13B 109.5 C8—C2—H2B 109.5 C7—C13—H13C 109.5 H2A—C2—H2B 108.1 H13A—C13—H13B 109.5 C9—C3—H3A 108.7 H13A—C13—H13C 109.5 C9—C3—H3B 108.7 H13B—C13—H13C 109.5 H3A—C3—H3B 107.6 F4—B—F3 111 (3) C10—C4—H4A 108.4 F4—B—F2 120 (3) C10—C4—H4B 108.4 F3—B—F2 108 (3) H4A—C4—H4B 107.4 F4—B—F1 101 (4) C11—C5—H5A 108.4 F3—B—F1 107 (3) C11—C5—H5B 108.4 F2—B—F1 109 (3) H5A—C5—H5B 107.4
Hydrogen-bond geometry (Å, º)
 D—H···A D—H H···A D···A D—H···A C5—H5B···O1i 0.97 2.75 3.45 (2) 129 C13—H13B···F2ii 0.96 2.43 3.27 (3) 147 C4—H4A···F2 0.97 2.56 3.48 (3) 159 C7—H7A···F4iii 0.97 2.67 3.46 (3) 140 C11—H11B···F3 0.96 2.75 3.47 (3) 133 C6—H6A···F1ii 0.97 2.81 3.67 (4) 147
 Symmetry codes: (i) x−1/2, −y+1, z; (ii) −x+1/2, y, z+1/2; (iii) −x, −y+1, z+1/2.

### Acknowledgements

I am deeply grateful to the late James A. Ibers, who suggested this problem and submitted the earlier communication on the structure.

### Funding information

Funding for this research was provided by: National Science Foundation.

### References

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