Tetra­kis(pyridine-κN)palladium(II) bis­(tetra­fluoridoborate)

The title complex, [Pd(C₅H₅N)₄](BF₄)₂, contains tetra­pyridine­palladium(II) cations residing on crystallographic inversion centres. These are linked by weak C—H...F inter­actions (involving disordered BF₄⁻ anions) [range 2.988 (12)–3.431 (10) Å], together with C—H...π(pyridine) inter­actions. The F atoms are disordered equally over two positions.

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](C-C) = 0.011 Å
• Disorder in solvent or counterion
• R factor = 0.046
• wR factor = 0.154
• Data-to-parameter ratio = 16.2

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT153_ALERT_1_C The su's on the Cell Axes   are Equal (x 100000)        700 Ang.
PLAT164_ALERT_4_C Nr. of Refined C-H H-Atoms in Heavy-At Struct...          7
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         C4
PLAT243_ALERT_4_C High  'Solvent' Ueq as Compared to Neighbors for        F1'
PLAT243_ALERT_4_C High  'Solvent' Ueq as Compared to Neighbors for        F2'
PLAT243_ALERT_4_C High  'Solvent' Ueq as Compared to Neighbors for        F3'
PLAT243_ALERT_4_C High  'Solvent' Ueq as Compared to Neighbors for        F4'
PLAT244_ALERT_4_C Low   'Solvent' Ueq as Compared to Neighbors for         F2
PLAT244_ALERT_4_C Low   'Solvent' Ueq as Compared to Neighbors for         F3
PLAT244_ALERT_4_C Low   'Solvent' Ueq as Compared to Neighbors for         F4
PLAT244_ALERT_4_C Low   'Solvent' Ueq as Compared to Neighbors for          B
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.07
PLAT302_ALERT_4_C Anion/Solvent Disorder .........................      44.00 Perc.
PLAT342_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...         11

Alert level G
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......         20

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
  14 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 ALERT type 3 Indicator that the structure quality may be low
  10 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

The design of supramolecular coordination compounds by self-assembly is a developing research area (Lehn, 1995, Braga et al., 1998). Four-coordinate Pd^II complexes with square-planar geometry and four pyridine ligands, in particular, is a potentially useful building block for producing an array of interesting molecular architectures by means of C—H···π-ring interactions, thanks to the mobility of pyridine planes. It is for that reason that we have tried to prepare the title compound (I) to be able to compare the results with the structure of the same compound with acetone solvate (Lutz et al., 2000).

Normally, the tetrakis(pyridine-N)palladium(II) ion has a square-planar coordination, with the anion occupying the apical positions of an octahedron. Pd···X lengths are 4.299 (5) Å in (I) (X = B); 4.028 (7) Å (X = B, Lutz et al., 2000); 4.4759 (11) Å in the orthorhombic phase and 4.100 (2) Å in the triclinic phase (X = I, Tebbe et al., 1996); 3.112 (2) Å (X = O, Liqing et al. 2005) and 3.079 (4) or 3.031 (3) Å (X = F, Holzbock et al., 2000). The packing will come defined by the solvate presence and the size of the anion which will alter, in addition, the dihedral angle between the pyridine planes. This angle is equal to 89.53 (19)° in (I), 89.62° in the Liqing structure, a range of 85.73 to 81.13° in the Holzbock structure, 85.33° in orthorhombic phase and 83.37° in triclinic phase of the Tebbe structure and 78.25 to 58.13° in the Lutz structure. The C—H···π-(ring) interaction only takes place in (I) and the triclinic phase of the Tebbe structure producing a one-dimensional-structure. The data for C4—H4···N2 (pyridine ring) (symmetry = 1/2 + x, 1/2 - y, 1/2 + z) are H-centroid distance 2.97 Å, γ = 20.28°. This fact suggests that the solvate absence and a dihedral angle between the pyridine planes next to 90° facilitate this interaction.

Related literature

For related literature, see: Braga et al. (1998); Holzbock et al. (2000); Lehn (1995); Liqing et al. (2005); Lutz et al. (2000); Ma et al. (2005); Tebbe et al. (1996).

S2. Experimental

A solution of 0.070 g (0.308 mmol) [PdCl₂(CH₃CN)₂] was dissolved in a mixture of CH₂Cl₂ (10 ml) and methanol (10 ml). About 0.1230 g, (0.625 mmol) of pyridine was added to a solution. Then, a solution of 0.070 g, (0.625 mmol) of NaBF₄ in methanol (2 ml) was added dropwise with vigorous stirring. After 2 h, stirring was stopped, and the product precipitated as yellow solid, was filtered, washed with diethylether, and dried under vacuum. Crystals were obtained by evaporation of acetonitrile solution. Yield: 0.15 g, (81%) - C₂₀H₂₀B₂F₈N₄Pd (596.42). (%): C, 40.27; H, 3.38; N, 9.39; found: C, 40.26; H, 3.37; N, 9.39. Conductivity (Ω^-1 cm² mol^-1, 1.03 x 10^-3 M in acetonitrile): 279. IR(KBr, cm^-1): ν(C=C)_py; ν(C=N)_py 1603, δ(C=C)_py; δ(C=N)_py 1448, ν(B—F) 1068, δ(C—H)_oop 769, 695. IR (polyethylene, cm^-1): ν(Pd—N)as(py) 472. ¹H NMR (250 MHz, [D₃]-acetonitrile solution) δ = 7.58–7.43 (m, 8H, py), 8.85–8.72 (m, 8H, py), 8.04–7.90 (m, 4H, py). ¹³C NMR (63 MHz, [D₃]-acetonitrile solution) δ = 128–126(py), 142–140(py), 154–152(py).

Computing details

Data collection: CAD-4-PC (Kretschmar, 1996); cell refinement: CAD-4-PC; data reduction: WinGX-PC (Farrugia, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP (Brueggemann & Schmid, 1990); software used to prepare material for publication: PLATON (Spek, 2003).

Figures

Fig. 1. The asymmetric unit of (I), showing the atomic numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. A position of the disorder of the BF4 has only been drawn for greater clarity of the figure.

Tetrakis(pyridine-κN)palladium(II) bis(tetrafluoridoborate)

Crystal data

[Pd(C5H5N)4](BF4)2	F(000) = 1184
Mr = 596.42	Dx = 1.643 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 25 reflections
a = 15.640 (7) Å	θ = 9–18°
b = 10.886 (7) Å	µ = 0.85 mm^−1
c = 15.711 (7) Å	T = 295 K
β = 115.63 (3)°	Prism, yellow
V = 2412 (2) Å^3	0.18 × 0.15 × 0.11 mm
Z = 4

Data collection

Enraf–Nonius CAD-4 diffractometer	Rint = 0.064
Radiation source: fine-focus sealed tube	θmax = 30.0°, θmin = 2.4°
Graphite monochromator	h = −21→21
ω/2θ' scans	k = −14→15
6864 measured reflections	l = −22→12
3521 independent reflections	3 standard reflections every 120 min
1872 reflections with I > 2σ(I)	intensity decay: none

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.046	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.154	H atoms treated by a mixture of independent and constrained refinement
S = 0.97	w = 1/[σ^2(Fo^2) + (0.0885P)^2] where P = (Fo^2 + 2Fc^2)/3
3521 reflections	(Δ/σ)max = 0.001
217 parameters	Δρmax = 0.96 e Å^−3
20 restraints	Δρmin = −0.52 e Å^−3

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Pd	0.2500	0.2500	0.5000	0.04425 (17)
N1	0.3643 (3)	0.3627 (3)	0.5562 (3)	0.0524 (10)
N2	0.2482 (3)	0.2718 (3)	0.3707 (3)	0.0515 (10)
C1	0.3518 (4)	0.4830 (5)	0.5591 (5)	0.0706 (16)
H1	0.281 (4)	0.507 (6)	0.540 (4)	0.085*
C2	0.4256 (5)	0.5640 (5)	0.5942 (5)	0.090 (2)
H2	0.4145	0.6479	0.5939	0.107*
C3	0.5147 (5)	0.5201 (7)	0.6291 (6)	0.107 (3)
H3	0.5662	0.5730	0.6560	0.128*
C4	0.5284 (5)	0.3985 (8)	0.6246 (7)	0.119 (3)
H4	0.5897	0.3678	0.6460	0.142*
C5	0.4529 (4)	0.3202 (5)	0.5888 (5)	0.081 (2)
H5	0.466 (6)	0.234 (5)	0.602 (5)	0.097*
C6	0.3069 (5)	0.2063 (5)	0.3457 (4)	0.0618 (14)
H6	0.339 (4)	0.159 (5)	0.392 (4)	0.074*
C7	0.3078 (5)	0.2172 (6)	0.2601 (5)	0.0747 (19)
H7	0.359 (4)	0.175 (6)	0.251 (4)	0.090*
C8	0.2451 (5)	0.2970 (7)	0.1942 (5)	0.0736 (17)
H8	0.246 (5)	0.302 (6)	0.139 (5)	0.088*
C9	0.1841 (5)	0.3641 (5)	0.2183 (4)	0.0753 (17)
H9	0.130 (4)	0.420 (6)	0.181 (4)	0.090*
C10	0.1872 (5)	0.3496 (5)	0.3071 (5)	0.0682 (15)
H10	0.139 (4)	0.375 (5)	0.328 (4)	0.082*
B	0.4188 (3)	0.0789 (4)	0.0683 (3)	0.0520 (13)
F1	0.3608 (6)	0.1363 (7)	0.1009 (6)	0.087 (4)	0.50
F1'	0.3416 (6)	0.1358 (9)	0.0789 (9)	0.126 (6)	0.50
F2	0.4665 (5)	0.1591 (5)	0.0370 (5)	0.074 (2)	0.50
F2'	0.4267 (10)	0.1392 (11)	−0.0085 (7)	0.209 (9)	0.50
F3	0.3647 (5)	−0.0047 (5)	−0.0055 (5)	0.078 (2)	0.50
F3'	0.3989 (8)	−0.0435 (5)	0.0473 (11)	0.171 (8)	0.50
F4	0.4867 (5)	0.0047 (7)	0.1429 (4)	0.095 (3)	0.50
F4'	0.5011 (6)	0.0967 (14)	0.1496 (6)	0.206 (8)	0.50

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Pd	0.0444 (3)	0.0326 (2)	0.0633 (3)	−0.0010 (3)	0.0304 (2)	−0.0053 (3)
N1	0.047 (2)	0.0369 (19)	0.075 (3)	0.0015 (16)	0.028 (2)	0.0004 (18)
N2	0.056 (2)	0.037 (2)	0.069 (2)	−0.0016 (15)	0.034 (2)	−0.0049 (16)
C1	0.064 (3)	0.037 (2)	0.107 (5)	0.000 (2)	0.033 (3)	0.002 (3)
C2	0.089 (5)	0.036 (3)	0.135 (6)	−0.014 (3)	0.041 (5)	−0.014 (4)
C3	0.070 (4)	0.070 (4)	0.149 (7)	−0.031 (4)	0.018 (4)	0.019 (5)
C4	0.046 (3)	0.093 (6)	0.184 (9)	0.002 (4)	0.020 (4)	0.028 (6)
C5	0.053 (3)	0.049 (3)	0.131 (6)	0.001 (2)	0.032 (4)	0.011 (3)
C6	0.073 (4)	0.048 (2)	0.082 (4)	0.001 (2)	0.050 (3)	−0.002 (3)
C7	0.087 (4)	0.068 (4)	0.094 (5)	−0.013 (3)	0.063 (4)	−0.018 (3)
C8	0.091 (5)	0.069 (3)	0.071 (4)	−0.018 (3)	0.044 (4)	−0.011 (3)
C9	0.094 (4)	0.055 (3)	0.069 (4)	−0.002 (3)	0.027 (3)	0.001 (3)
C10	0.084 (4)	0.045 (3)	0.084 (4)	0.005 (3)	0.044 (3)	0.001 (3)
B	0.057 (3)	0.050 (3)	0.053 (3)	−0.009 (3)	0.027 (3)	0.000 (2)
F1	0.106 (7)	0.068 (7)	0.130 (8)	0.010 (6)	0.092 (7)	−0.010 (6)
F1'	0.087 (7)	0.124 (12)	0.189 (13)	−0.034 (7)	0.079 (8)	−0.083 (10)
F2	0.083 (5)	0.050 (4)	0.123 (7)	−0.013 (3)	0.076 (5)	0.007 (4)
F2'	0.31 (2)	0.232 (19)	0.121 (11)	0.107 (17)	0.131 (13)	0.071 (11)
F3	0.075 (5)	0.051 (4)	0.096 (5)	−0.010 (4)	0.026 (4)	−0.032 (4)
F3'	0.166 (12)	0.038 (4)	0.39 (2)	−0.003 (6)	0.201 (15)	−0.006 (9)
F4	0.097 (6)	0.101 (7)	0.062 (5)	0.015 (5)	0.013 (4)	0.020 (5)
F4'	0.139 (11)	0.25 (2)	0.138 (11)	0.006 (13)	−0.023 (8)	−0.043 (12)

Geometric parameters (Å, º)

Pd—N1^i	2.028 (4)	C6—C7	1.357 (9)
Pd—N1	2.028 (4)	C6—H6	0.85 (6)
Pd—N2^i	2.033 (5)	C7—C8	1.382 (11)
Pd—N2	2.033 (5)	C7—H7	0.99 (6)
N1—C1	1.328 (6)	C8—C9	1.379 (9)
N1—C5	1.335 (7)	C8—H8	0.88 (7)
N2—C10	1.342 (7)	C9—C10	1.384 (9)
N2—C6	1.348 (7)	C9—H9	1.00 (6)
C1—C2	1.365 (8)	C10—H10	0.99 (6)
C1—H1	1.05 (6)	B—F1	1.370 (6)
C2—C3	1.344 (10)	B—F2	1.371 (5)
C2—H2	0.9300	B—F3'	1.375 (6)
C3—C4	1.348 (11)	B—F4'	1.380 (7)
C3—H3	0.9300	B—F2'	1.425 (7)
C4—C5	1.365 (9)	B—F3	1.428 (6)
C4—H4	0.9300	B—F1'	1.430 (7)
C5—H5	0.96 (6)	B—F4	1.441 (6)
N1^i—Pd—N1	180.00 (17)	N2—C6—C7	122.9 (6)
N1^i—Pd—N2^i	89.63 (17)	N2—C6—H6	108 (4)
N1—Pd—N2^i	90.37 (17)	C7—C6—H6	129 (4)
N1^i—Pd—N2	90.37 (17)	C6—C7—C8	119.3 (6)
N1—Pd—N2	89.63 (17)	C6—C7—H7	117 (4)
N2^i—Pd—N2	180.0	C8—C7—H7	123 (4)
C1—N1—C5	118.2 (5)	C9—C8—C7	118.6 (6)
C1—N1—Pd	119.8 (4)	C9—C8—H8	123 (5)
C5—N1—Pd	122.0 (4)	C7—C8—H8	118 (5)
C10—N2—C6	118.1 (5)	C8—C9—C10	119.3 (6)
C10—N2—Pd	121.1 (4)	C8—C9—H9	132 (4)
C6—N2—Pd	120.8 (4)	C10—C9—H9	108 (4)
N1—C1—C2	122.7 (6)	N2—C10—C9	121.8 (6)
N1—C1—H1	113 (4)	N2—C10—H10	109 (3)
C2—C1—H1	124 (4)	C9—C10—H10	128 (3)
C3—C2—C1	118.8 (6)	F1—B—F2	113.2 (4)
C3—C2—H2	120.6	F1—B—F3	109.8 (4)
C1—C2—H2	120.6	F2—B—F3	109.7 (4)
C2—C3—C4	119.2 (6)	F1—B—F4	109.0 (4)
C2—C3—H3	120.4	F2—B—F4	109.0 (4)
C4—C3—H3	120.4	F3—B—F4	105.8 (4)
C3—C4—C5	120.4 (7)	F3'—B—F4'	112.4 (4)
C3—C4—H4	119.8	F3'—B—F2'	109.7 (4)
C5—C4—H4	119.8	F3'—B—F1'	109.4 (4)
N1—C5—C4	120.7 (6)	F4'—B—F2'	109.4 (4)
N1—C5—H5	121 (5)	F4'—B—F1'	109.1 (4)
C4—C5—H5	117 (5)	F2'—B—F1'	106.6 (4)

Symmetry code: (i) −x+1/2, −y+1/2, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C4—H4···Cg1^ii	0.93	2.97	3.800 (10)	150

Symmetry code: (ii) x+1/2, −y+1/2, z−1/2.