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Acta Cryst. (2008). E64, m1449    [ doi:10.1107/S1600536808033679 ]

Tetrapyrazineplatinum(II) bis(tetrafluoroborate) acetonitrile hemisolvate

P. J. Derry, X. Wang and B. W. Smucker

Abstract top

The improved synthesis and characterization of tetrapyrazineplatinum(II) bis(tetrafluoroborate) acetonitrile hemisolvate, [Pt(C4H4N2)4](BF4)2·0.5CH3CN, is reported. The unit cell contains a half equivalent of an acetonitrile solvent molecule per tetrapyrazineplatinum(II) ion. The coordination geometry of the PtII ion is almost square-planar, with the Pt atom residing on an inversion center. The BF4- counter-anion, located at a general position, has an idealized tetrahedral geometry and an acetonitrile solvent molecule, the methyl group of which is disordered over two equal positions, sits on a twofold rotation axis.

Comment top

The synthesis of the nitrate salt of tetrapyrazineplatinum(II), which has use as a precursor to other platinum compounds, was recently reported in low yield (Klika et al., 2007). In our pursuit of utilizing pyrazine as a bridging ligand to form compounds which add to the growing number of supramolecular metallacycles such as those by Schweiger et al. (2001), Willermann et al. (2006), and Derossi et al. (2007), to name but a few, we sought a more favorable yield for this tetrapyrazineplatinum(II) precursor. We settled on a synthetic method that generates a high yield of tetrapyrazineplatinum(II) tetrafluoroborate following the use of a large excess of pyrazine and nitromethane, a non-coordinating solvent which Pearson et al. (1960) reported as increasing the lability of a ligand bound to PtII.

The structure of the cation of tetrapyrazineplatinum(II) tetrafluoroborate (Figure 1) has a square planar conformation. The PtII ion resides on an inversion center with Pt1—N1 and Pt1—N2 distances of 2.026 (6) and 2.012 (5) Å, respectively. The two unique coordinated pyrazine ligands (N1 C1 C2 C3 C4 N3, N2 C5 C6 C7 C8 N4) are slightly canted relative to the (N1—Pt—N2) plane (dihedral angles between pyrazine planes and N1—Pt1—N2 plane are 84.1 (3)° and 69.3 (3)°, respectively). The canted conformation of the pyrazine ligands around the platinum atom is similar to that of pyridine in the closely-related tetrapyridine platinum(II) chloride trihydrate reported by Wei et al. (1989).

The tetrafluoroborate anion is positioned near three tetrapyrazineplatinum(II) cations and oriented such that every flourine atom is between 2.1 and 2.4Å from a hydrogen atom in the 3 or 5 position of a coordinated pyrazine. (Figure 2).

Related literature top

For related literature, see: Derossi et al. (2007); Klika et al. (2007); Pearson et al. (1960); Schweiger et al. (2001); Wei et al. (1989); Wendt et al. (1997); Willermann et al. (2006). It would be much more useful to readers if the "Related literature" section had some kind of simple sub-division, so that, instead of just "For related literature, see···" it said, for example, "For general background, see···. For related structures, see···; etc. Please revise this section as indicated.

Experimental top

53 mg (0.099 mmol) of [Pt(NCMe)4](BF4)2, (synthesized according to Wendt et al. (1997)) and 344 mg (4.3 mmol) of pyrazine (Aldrich) were dissolved in 11 ml of degassed MeNO2. The schlenk flask was covered in foil and the stirring solution was moderately heated under a nitrogen environment for 18 h. 50 ml of degassed Et2O was added, the solution was cooled in an ice bath, and the resulting white solid was isolated by removal of the liquid via cannula and washing with 2x5mL degassed Et2O. The resulting solid was vacuum dried to give 67 mg (98% yield.) of a white solid. FT—IR (nujol, CsI plates): (cm-1) 1433(s,C—H), 1055 (b,B—F), 520 and 503 (w, Pt—N). 1H NMR (d-MeNO2): 9.00 (m) and 8.79 (m). ESI-M. S. 602 (Pt(C4H4N2)4)(BF4)+), 258 ([Pt(C4H4N2)4]2+).

Pale yellow crystals were grown by liquid diffusion of diethylether into a nitromethane solution containing tetrapyrazineplatinum(II) tetrafluoroborate and excess pyrazine.

Refinement top

The positions of the pyrazine and methyl H atoms were refined using a riding model, in accordance with the HFIX 43 and HFIX 137 instructions of SHELXL97, with pyrazine C—H distances of 0.93 Å, methyl C—H distance of 0.96 Å, and with Uiso(H) values of 1.2Ueq(C) for pyrazine and 1.5Ueq(C) for methyl group in the acetonitrile solvent molecule. The acetonitrile solvate resides on a crystallographic two-fold axis with the methyl H atoms disordered in two position. Each of the methyl H atoms were refined accordingly as half occupied. The largest positive and negative peaks in the final difference map are 1.58 and -0.45 Å, respectively, from the Pt atom.

Computing details top

Data collection: APEX2 (Bruker, 2006); cell refinement: APEX2 (Bruker, 2006); data reduction: APEX2 (Bruker, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. Ellipsoid plot of tetrapyrazineplatinum(II) tetrafluoroborate. Unlabelled atoms are generated via inversion through Pt1, symmetry code: -x, -y + 1, -z (50% probability displacement ellipsoids).
[Figure 2] Fig. 2. View of the hydrogen bonding between the tetrafluoroborate anion and the tetrapyrazineplatinum(II) cation (50% probability displacement ellipsoids).
tetrapyrazineplatinum(II) bis(tetrafluoroborate) acetonitrile hemisolvate top
Crystal data top
[Pt(C4H4N2)4](BF4)2·0.5C2H3NF(000) = 1356
Mr = 709.6Dx = 1.821 Mg m−3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 8501 reflections
a = 13.862 (4) Åθ = 2.3–27.8°
b = 10.819 (3) ŵ = 5.50 mm−1
c = 17.262 (5) ÅT = 296 K
β = 91.607 (3)°Block, pale yellow
V = 2587.8 (13) Å30.27 × 0.21 × 0.19 mm
Z = 4
Data collection top
Bruker APEXII CCD
diffractometer		1846 reflections with I > 2σ(I)
ω scansRint = 0.039
Absorption correction: multi-scan
(SADABS; Bruker, 2004)		θmax = 26.7°, θmin = 2.4°
Tmin = 0.246, Tmax = 0.352h = −17→17
11212 measured reflectionsk = −13→13
2736 independent reflectionsl = −21→21
Refinement top
Refinement on F22 restraints
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.033 w = 1/[σ2(Fo2) + (0.0518P)2 + 10.4546P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.114(Δ/σ)max = 0.012
S = 1.20Δρmax = 1.58 e Å−3
2736 reflectionsΔρmin = −0.45 e Å−3
167 parameters
Crystal data top
[Pt(C4H4N2)4](BF4)2·0.5C2H3NV = 2587.8 (13) Å3
Mr = 709.6Z = 4
Monoclinic, C2/cMo Kα radiation
a = 13.862 (4) ŵ = 5.50 mm−1
b = 10.819 (3) ÅT = 296 K
c = 17.262 (5) Å0.27 × 0.21 × 0.19 mm
β = 91.607 (3)°
Data collection top
Bruker APEXII CCD
diffractometer		2736 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2004)		1846 reflections with I > 2σ(I)
Tmin = 0.246, Tmax = 0.352Rint = 0.039
11212 measured reflectionsθmax = 26.7°
Refinement top
R[F2 > 2σ(F2)] = 0.033 w = 1/[σ2(Fo2) + (0.0518P)2 + 10.4546P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.114Δρmax = 1.58 e Å−3
S = 1.20Δρmin = −0.45 e Å−3
2736 reflectionsAbsolute structure: ?
167 parametersFlack parameter: ?
2 restraintsRogers parameter: ?
H-atom parameters constrained
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*/UeqOcc. (<1)
Pt100.500.04102 (14)
N10.0732 (4)0.5078 (5)0.1031 (4)0.0463 (13)
N20.1147 (4)0.4171 (5)−0.0466 (3)0.0435 (13)
N30.1705 (8)0.5173 (9)0.2459 (5)0.090 (3)
N40.2743 (5)0.3006 (7)−0.1078 (4)0.0693 (19)
C10.1234 (7)0.6071 (9)0.1267 (5)0.072 (3)
H1A0.12670.67560.09430.087*
C20.1699 (8)0.6096 (12)0.1971 (6)0.092 (3)
H2A0.20310.68110.21130.11*
C30.1246 (7)0.4181 (12)0.2223 (5)0.081 (3)
H3A0.12570.34910.25450.097*
C40.0729 (6)0.4100 (8)0.1496 (5)0.060 (2)
H4A0.040.33830.13520.072*
C50.1983 (6)0.4785 (6)−0.0567 (5)0.0509 (19)
H5A0.20270.5615−0.0430.061*
C60.2764 (6)0.4203 (9)−0.0868 (5)0.066 (2)
H6A0.33290.465−0.0930.079*
C70.1921 (7)0.2422 (8)−0.0975 (5)0.063 (2)
H7A0.18810.1592−0.11120.076*
C80.1128 (6)0.2975 (7)−0.0678 (5)0.058 (2)
H8A0.05660.2518−0.06220.07*
B10.1048 (10)0.1540 (11)0.4316 (8)0.081 (3)
F10.1311 (10)0.1855 (9)0.5039 (6)0.226 (6)
F20.1324 (7)0.2427 (8)0.3805 (6)0.163 (4)
F30.0102 (6)0.1483 (9)0.4290 (6)0.172 (4)
F40.1480 (6)0.0465 (7)0.4153 (5)0.125 (3)
N1S00.224 (3)−0.250.174 (15)*0.5
C1S00.124 (3)−0.250.093 (9)*0.5
C2S0−0.014 (3)−0.250.16 (2)*0.5
H2S10.039−0.0435−0.2070.241*0.25
H2S20.0259−0.0435−0.29760.241*0.25
H2S3−0.0649−0.0435−0.24540.241*0.25
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Pt10.0407 (2)0.0471 (2)0.0350 (2)0.00181 (19)−0.00349 (13)−0.00503 (18)
N10.045 (3)0.053 (3)0.041 (3)0.007 (3)−0.003 (2)−0.006 (3)
N20.045 (3)0.049 (3)0.037 (3)0.004 (3)−0.003 (2)0.002 (2)
N30.092 (7)0.128 (9)0.049 (5)−0.012 (5)−0.026 (4)−0.011 (5)
N40.054 (4)0.081 (5)0.073 (5)0.015 (4)0.003 (3)−0.014 (4)
C10.082 (6)0.074 (6)0.060 (5)−0.027 (5)−0.016 (5)−0.004 (4)
C20.101 (8)0.111 (9)0.062 (6)−0.038 (7)−0.028 (6)−0.007 (6)
C30.080 (6)0.108 (9)0.053 (5)0.021 (6)−0.004 (5)0.013 (6)
C40.063 (5)0.062 (5)0.055 (5)0.006 (4)−0.016 (4)0.004 (4)
C50.047 (4)0.047 (5)0.058 (5)0.000 (3)−0.001 (3)−0.001 (3)
C60.046 (4)0.080 (6)0.072 (6)0.002 (4)0.005 (4)0.001 (5)
C70.074 (6)0.049 (5)0.066 (5)0.016 (4)−0.004 (4)−0.013 (4)
C80.061 (5)0.052 (4)0.062 (5)−0.004 (4)0.000 (4)−0.012 (4)
B10.091 (9)0.064 (7)0.088 (9)0.024 (6)−0.018 (7)−0.003 (6)
F10.329 (15)0.179 (9)0.166 (9)0.089 (9)−0.080 (10)−0.091 (8)
F20.192 (9)0.109 (6)0.188 (9)0.034 (6)0.032 (7)0.062 (6)
F30.088 (5)0.200 (9)0.227 (11)0.021 (6)−0.015 (6)0.031 (7)
F40.172 (8)0.073 (3)0.131 (6)0.050 (5)−0.001 (5)−0.006 (4)
Geometric parameters (Å, °) top
Pt1—N2i2.012 (5)C4—H4A0.93
Pt1—N22.012 (5)C5—C61.368 (11)
Pt1—N1i2.026 (6)C5—H5A0.93
Pt1—N12.026 (6)C6—H6A0.93
N1—C41.327 (10)C7—C81.364 (11)
N1—C11.337 (10)C7—H7A0.93
N2—C81.345 (9)C8—H8A0.93
N2—C51.352 (9)B1—F31.312 (14)
N3—C31.307 (14)B1—F11.335 (14)
N3—C21.307 (13)B1—F41.342 (12)
N4—C71.319 (11)B1—F21.365 (14)
N4—C61.344 (11)N1S—C1S1.086 (14)
C1—C21.360 (12)C1S—C2S1.492 (10)
C1—H1A0.93C2S—H2S10.96
C2—H2A0.93C2S—H2S20.96
C3—C41.432 (12)C2S—H2S30.96
C3—H3A0.93
N2i—Pt1—N2180.0 (3)N2—C5—C6120.9 (7)
N2i—Pt1—N1i89.3 (2)N2—C5—H5A119.6
N2—Pt1—N1i90.7 (2)C6—C5—H5A119.6
N2i—Pt1—N190.7 (2)N4—C6—C5122.3 (8)
N2—Pt1—N189.3 (2)N4—C6—H6A118.8
N1i—Pt1—N1180.00 (18)C5—C6—H6A118.8
C4—N1—C1117.9 (7)N4—C7—C8123.3 (8)
C4—N1—Pt1119.2 (5)N4—C7—H7A118.4
C1—N1—Pt1123.0 (5)C8—C7—H7A118.4
C8—N2—C5116.6 (6)N2—C8—C7121.0 (8)
C8—N2—Pt1121.9 (5)N2—C8—H8A119.5
C5—N2—Pt1121.5 (5)C7—C8—H8A119.5
C3—N3—C2115.6 (9)F3—B1—F1106.8 (12)
C7—N4—C6115.9 (7)F3—B1—F4113.9 (12)
N1—C1—C2121.1 (9)F1—B1—F4107.8 (10)
N1—C1—H1A119.4F3—B1—F2108.0 (10)
C2—C1—H1A119.4F1—B1—F2110.5 (12)
N3—C2—C1123.8 (10)F4—B1—F2109.8 (11)
N3—C2—H2A118.1N1S—C1S—C2S180.000 (5)
C1—C2—H2A118.1C1S—C2S—H2S1109.5
N3—C3—C4123.4 (10)C1S—C2S—H2S2109.5
N3—C3—H3A118.3H2S1—C2S—H2S2109.5
C4—C3—H3A118.3C1S—C2S—H2S3109.5
N1—C4—C3118.1 (8)H2S1—C2S—H2S3109.5
N1—C4—H4A120.9H2S2—C2S—H2S3109.5
C3—C4—H4A120.9
Symmetry codes: (i) −x, −y+1, −z.
Acknowledgements top

This research was funded by a chemistry department grant from the Welch Foundation (grant No. AD-0007). X-ray data were collected at the University of North Texas. We are grateful to Guido F. Verbeck at UNT for the MS measurements.

references
References top

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