Tetra­pyrazine­platinum(II) bis­(tetra­fluoro­borate) acetonitrile hemisolvate

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

doi:10.1107/S1600536808033679

metal-organic compounds

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Volume 64| Part 11| November 2008| Page m1449

doi:10.1107/S1600536808033679

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Tetrapyrazineplatinum(II) bis(tetrafluoroborate) acetonitrile hemisolvate

Paul J. Derry,^a Xiaoping Wang ^b and Bradley W. Smucker ^a ^*

^aDepartment of Chemistry, Austin College, 900 North Grand, Sherman, TX 75090-4400, USA, and ^bOak Ridge National Laboratory, PO Box 2008 MS6460, Oak Ridge, TN 37831-6460, USA
^*Correspondence e-mail: bsmucker@austincollege.edu

(Received 1 September 2008; accepted 15 October 2008; online 22 October 2008)

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 Pt^II 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.

Related literature

For general background, see: Derossi et al. (2007 ); Klika et al. (2007 ); Pearson et al. (1960 ); Schweiger et al. (2001 ); Wendt et al. (1997 ); Willermann et al. (2006 ). For related structures, see: Wei et al. (1989 ).

Experimental

Crystal data

[Pt(C₄H₄N₂)₄](BF₄)₂·0.5C₂H₃N
M_r = 709.6
Monoclinic, C 2/c
a = 13.862 (4) Å
b = 10.819 (3) Å
c = 17.262 (5) Å
β = 91.607 (3)°
V = 2587.8 (13) Å³
Z = 4
Mo Kα radiation
μ = 5.50 mm⁻¹
T = 296 (2) K
0.27 × 0.21 × 0.19 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2004 ) T_min = 0.246, T_max = 0.352
11212 measured reflections
2736 independent reflections
1846 reflections with I > 2σ(I)
R_int = 0.039

Refinement

R[F² > 2σ(F²)] = 0.033
wR(F²) = 0.114
S = 1.20
2736 reflections
167 parameters
2 restraints
H-atom parameters constrained
Δρ_max = 1.58 e Å⁻³
Δρ_min = −0.45 e Å⁻³

Data collection: APEX2 (Bruker, 2006 ); cell refinement: APEX2; data reduction: APEX2; 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 and WinGX (Farrugia, 1999 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808033679/pk2119sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808033679/pk2119Isup2.hkl

checkCIF report

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 Pt^II.

The structure of the cation of tetrapyrazineplatinum(II) tetrafluoroborate (Figure 1) has a square planar conformation. The Pt^II 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.

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

	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).
	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)₂·0.5C₂H₃N	F(000) = 1356
M_r = 709.6	D_x = 1.821 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 8501 reflections
a = 13.862 (4) Å	θ = 2.3–27.8°
b = 10.819 (3) Å	µ = 5.50 mm⁻¹
c = 17.262 (5) Å	T = 296 K
β = 91.607 (3)°	Block, pale yellow
V = 2587.8 (13) Å³	0.27 × 0.21 × 0.19 mm
Z = 4

Data collection top

Bruker APEXII CCD diffractometer	1846 reflections with I > 2σ(I)
ω scans	R_int = 0.039
Absorption correction: multi-scan (SADABS; Bruker, 2004)	θ_max = 26.7°, θ_min = 2.4°
T_min = 0.246, T_max = 0.352	h = −17→17
11212 measured reflections	k = −13→13
2736 independent reflections	l = −21→21

Refinement top

Refinement on F²	2 restraints
Least-squares matrix: full	H-atom parameters constrained
R[F² > 2σ(F²)] = 0.033	w = 1/[σ²(F_o²) + (0.0518P)² + 10.4546P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.114	(Δ/σ)_max = 0.012
S = 1.20	Δρ_max = 1.58 e Å⁻³
2736 reflections	Δρ_min = −0.45 e Å⁻³
167 parameters

Crystal data top

[Pt(C₄H₄N₂)₄](BF₄)₂·0.5C₂H₃N	V = 2587.8 (13) Å³
M_r = 709.6	Z = 4
Monoclinic, C2/c	Mo Kα radiation
a = 13.862 (4) Å	µ = 5.50 mm⁻¹
b = 10.819 (3) Å	T = 296 K
c = 17.262 (5) Å	0.27 × 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)
T_min = 0.246, T_max = 0.352	R_int = 0.039
11212 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.033	2 restraints
wR(F²) = 0.114	H-atom parameters constrained
S = 1.20	w = 1/[σ²(F_o²) + (0.0518P)² + 10.4546P] where P = (F_o² + 2F_c²)/3
2736 reflections	Δρ_max = 1.58 e Å⁻³
167 parameters	Δρ_min = −0.45 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

	x	y	z	U_iso*/U_eq	Occ. (<1)
Pt1	0	0.5	0	0.04102 (14)
N1	0.0732 (4)	0.5078 (5)	0.1031 (4)	0.0463 (13)
N2	0.1147 (4)	0.4171 (5)	−0.0466 (3)	0.0435 (13)
N3	0.1705 (8)	0.5173 (9)	0.2459 (5)	0.090 (3)
N4	0.2743 (5)	0.3006 (7)	−0.1078 (4)	0.0693 (19)
C1	0.1234 (7)	0.6071 (9)	0.1267 (5)	0.072 (3)
H1A	0.1267	0.6756	0.0943	0.087*
C2	0.1699 (8)	0.6096 (12)	0.1971 (6)	0.092 (3)
H2A	0.2031	0.6811	0.2113	0.11*
C3	0.1246 (7)	0.4181 (12)	0.2223 (5)	0.081 (3)
H3A	0.1257	0.3491	0.2545	0.097*
C4	0.0729 (6)	0.4100 (8)	0.1496 (5)	0.060 (2)
H4A	0.04	0.3383	0.1352	0.072*
C5	0.1983 (6)	0.4785 (6)	−0.0567 (5)	0.0509 (19)
H5A	0.2027	0.5615	−0.043	0.061*
C6	0.2764 (6)	0.4203 (9)	−0.0868 (5)	0.066 (2)
H6A	0.3329	0.465	−0.093	0.079*
C7	0.1921 (7)	0.2422 (8)	−0.0975 (5)	0.063 (2)
H7A	0.1881	0.1592	−0.1112	0.076*
C8	0.1128 (6)	0.2975 (7)	−0.0678 (5)	0.058 (2)
H8A	0.0566	0.2518	−0.0622	0.07*
B1	0.1048 (10)	0.1540 (11)	0.4316 (8)	0.081 (3)
F1	0.1311 (10)	0.1855 (9)	0.5039 (6)	0.226 (6)
F2	0.1324 (7)	0.2427 (8)	0.3805 (6)	0.163 (4)
F3	0.0102 (6)	0.1483 (9)	0.4290 (6)	0.172 (4)
F4	0.1480 (6)	0.0465 (7)	0.4153 (5)	0.125 (3)
N1S	0	0.224 (3)	−0.25	0.174 (15)*	0.5
C1S	0	0.124 (3)	−0.25	0.093 (9)*	0.5
C2S	0	−0.014 (3)	−0.25	0.16 (2)*	0.5
H2S1	0.039	−0.0435	−0.207	0.241*	0.25
H2S2	0.0259	−0.0435	−0.2976	0.241*	0.25
H2S3	−0.0649	−0.0435	−0.2454	0.241*	0.25

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Pt1	0.0407 (2)	0.0471 (2)	0.0350 (2)	0.00181 (19)	−0.00349 (13)	−0.00503 (18)
N1	0.045 (3)	0.053 (3)	0.041 (3)	0.007 (3)	−0.003 (2)	−0.006 (3)
N2	0.045 (3)	0.049 (3)	0.037 (3)	0.004 (3)	−0.003 (2)	0.002 (2)
N3	0.092 (7)	0.128 (9)	0.049 (5)	−0.012 (5)	−0.026 (4)	−0.011 (5)
N4	0.054 (4)	0.081 (5)	0.073 (5)	0.015 (4)	0.003 (3)	−0.014 (4)
C1	0.082 (6)	0.074 (6)	0.060 (5)	−0.027 (5)	−0.016 (5)	−0.004 (4)
C2	0.101 (8)	0.111 (9)	0.062 (6)	−0.038 (7)	−0.028 (6)	−0.007 (6)
C3	0.080 (6)	0.108 (9)	0.053 (5)	0.021 (6)	−0.004 (5)	0.013 (6)
C4	0.063 (5)	0.062 (5)	0.055 (5)	0.006 (4)	−0.016 (4)	0.004 (4)
C5	0.047 (4)	0.047 (5)	0.058 (5)	0.000 (3)	−0.001 (3)	−0.001 (3)
C6	0.046 (4)	0.080 (6)	0.072 (6)	0.002 (4)	0.005 (4)	0.001 (5)
C7	0.074 (6)	0.049 (5)	0.066 (5)	0.016 (4)	−0.004 (4)	−0.013 (4)
C8	0.061 (5)	0.052 (4)	0.062 (5)	−0.004 (4)	0.000 (4)	−0.012 (4)
B1	0.091 (9)	0.064 (7)	0.088 (9)	0.024 (6)	−0.018 (7)	−0.003 (6)
F1	0.329 (15)	0.179 (9)	0.166 (9)	0.089 (9)	−0.080 (10)	−0.091 (8)
F2	0.192 (9)	0.109 (6)	0.188 (9)	0.034 (6)	0.032 (7)	0.062 (6)
F3	0.088 (5)	0.200 (9)	0.227 (11)	0.021 (6)	−0.015 (6)	0.031 (7)
F4	0.172 (8)	0.073 (3)	0.131 (6)	0.050 (5)	−0.001 (5)	−0.006 (4)

Geometric parameters (Å, º) top

Pt1—N2ⁱ	2.012 (5)	C4—H4A	0.93
Pt1—N2	2.012 (5)	C5—C6	1.368 (11)
Pt1—N1ⁱ	2.026 (6)	C5—H5A	0.93
Pt1—N1	2.026 (6)	C6—H6A	0.93
N1—C4	1.327 (10)	C7—C8	1.364 (11)
N1—C1	1.337 (10)	C7—H7A	0.93
N2—C8	1.345 (9)	C8—H8A	0.93
N2—C5	1.352 (9)	B1—F3	1.312 (14)
N3—C3	1.307 (14)	B1—F1	1.335 (14)
N3—C2	1.307 (13)	B1—F4	1.342 (12)
N4—C7	1.319 (11)	B1—F2	1.365 (14)
N4—C6	1.344 (11)	N1S—C1S	1.086 (14)
C1—C2	1.360 (12)	C1S—C2S	1.492 (10)
C1—H1A	0.93	C2S—H2S1	0.96
C2—H2A	0.93	C2S—H2S2	0.96
C3—C4	1.432 (12)	C2S—H2S3	0.96
C3—H3A	0.93

N2ⁱ—Pt1—N2	180.0 (3)	N2—C5—C6	120.9 (7)
N2ⁱ—Pt1—N1ⁱ	89.3 (2)	N2—C5—H5A	119.6
N2—Pt1—N1ⁱ	90.7 (2)	C6—C5—H5A	119.6
N2ⁱ—Pt1—N1	90.7 (2)	N4—C6—C5	122.3 (8)
N2—Pt1—N1	89.3 (2)	N4—C6—H6A	118.8
N1ⁱ—Pt1—N1	180.00 (18)	C5—C6—H6A	118.8
C4—N1—C1	117.9 (7)	N4—C7—C8	123.3 (8)
C4—N1—Pt1	119.2 (5)	N4—C7—H7A	118.4
C1—N1—Pt1	123.0 (5)	C8—C7—H7A	118.4
C8—N2—C5	116.6 (6)	N2—C8—C7	121.0 (8)
C8—N2—Pt1	121.9 (5)	N2—C8—H8A	119.5
C5—N2—Pt1	121.5 (5)	C7—C8—H8A	119.5
C3—N3—C2	115.6 (9)	F3—B1—F1	106.8 (12)
C7—N4—C6	115.9 (7)	F3—B1—F4	113.9 (12)
N1—C1—C2	121.1 (9)	F1—B1—F4	107.8 (10)
N1—C1—H1A	119.4	F3—B1—F2	108.0 (10)
C2—C1—H1A	119.4	F1—B1—F2	110.5 (12)
N3—C2—C1	123.8 (10)	F4—B1—F2	109.8 (11)
N3—C2—H2A	118.1	N1S—C1S—C2S	180.000 (5)
C1—C2—H2A	118.1	C1S—C2S—H2S1	109.5
N3—C3—C4	123.4 (10)	C1S—C2S—H2S2	109.5
N3—C3—H3A	118.3	H2S1—C2S—H2S2	109.5
C4—C3—H3A	118.3	C1S—C2S—H2S3	109.5
N1—C4—C3	118.1 (8)	H2S1—C2S—H2S3	109.5
N1—C4—H4A	120.9	H2S2—C2S—H2S3	109.5
C3—C4—H4A	120.9

Symmetry code: (i) −x, −y+1, −z.

Experimental details

Crystal data
Chemical formula	[Pt(C₄H₄N₂)₄](BF₄)₂·0.5C₂H₃N
M_r	709.6
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	296
a, b, c (Å)	13.862 (4), 10.819 (3), 17.262 (5)
β (°)	91.607 (3)
V (Å³)	2587.8 (13)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	5.50
Crystal size (mm)	0.27 × 0.21 × 0.19

Data collection
Diffractometer	Bruker APEXII CCD diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2004)
T_min, T_max	0.246, 0.352
No. of measured, independent and observed [I > 2σ(I)] reflections	11212, 2736, 1846
R_int	0.039
(sin θ/λ)_max (Å⁻¹)	0.632

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.033, 0.114, 1.20
No. of reflections	2736
No. of parameters	167
No. of restraints	2
H-atom treatment	H-atom parameters constrained
	w = 1/[σ²(F_o²) + (0.0518P)² + 10.4546P] where P = (F_o² + 2F_c²)/3
Δρ_max, Δρ_min (e Å⁻³)	1.58, −0.45

Computer programs: APEX2 (Bruker, 2006), SHELXS97 (Sheldrick, 2008), XP in SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2003), SHELXL97 (Sheldrick, 2008) and WinGX (Farrugia, 1999).

Acknowledgements

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.

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