trans-Dibromidotetra­kis­(pyridine-κN)ruthenium(II)

The title complex, [RuBr₂(C₅H₅N)₄], contains two independent complex mol­ecules in each of which the Ru^II atom is located on a site of 222 symmetry and has a distorted octa­hedral coordination geometry with four pyridine N atoms and two Br atoms. The Br aroms are trans-disposed as a result of symmetry.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.025
• wR factor = 0.069
• Data-to-parameter ratio = 19.4

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for        Ru2
PLAT905_ALERT_3_C Negative K value in the Analysis of Variance ...     -1.566
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          3
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600         33
PLAT913_ALERT_3_C Missing # of Very Strong Reflections in FCF ....          8

Alert level G
PLAT005_ALERT_5_G No _iucr_refine_instructions_details  in the CIF          ?
PLAT083_ALERT_2_G SHELXL Second Parameter in WGHT Unusually Large.      11.68
PLAT232_ALERT_2_G Hirshfeld Test Diff (M-X)  Ru1    --  Br1     ..       20.0 su
PLAT232_ALERT_2_G Hirshfeld Test Diff (M-X)  Ru2    --  Br2     ..       15.7 su
PLAT912_ALERT_4_G Missing # of FCF Reflections Above STh/L=  0.600         10

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   5 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   5 ALERT level G = General information/check it is not something unexpected

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

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S1. Comment

Coordination chemistry of ruthenium complexes has been studied in last few decades because of their versatile and diverse applications in molecular catalysis (Pagliaro et al., 2005) and bioinorganic chemistry (van Rijt & Sadler, 2009). As part of our long-standing interest in the ruthenium complexes with σ-donor ligands such as thiolate, pyridine and phosphine (Zhang et al., 2005), we have investigated the reactivity of the starting ruthenium compounds such as RuCl₂(PPh₃)₃, RuHCl(CO)(PPh₃)₃ and RuCl₂(dmso)₄ (dmso = dimethyl sulfoxide) with mono-, bi- and poly-dentate ligands (Wu et al., 2009). Here we report the crystal structure of the mononuclear ruthenium(II) complex.

In the title complex, there are two independent complex molecules with a perpendicular arrangement. Each Ru^II atom is located on a 222 symmetry. No significant differences in bonding parameters between these two molecules are found. One of the molecular structures is depicted in Fig. 1. The coordination geometry of the Ru^II atom is octahedral with four pyridine N atoms and two Br atoms. The Ru—N bond lengths (Table 1) are in the range of those found in related structures of ruthenium(II) complexes retrieved from the Cambridge Structural Database (Allen, 2002). The Ru—Br bond lengths are comparable to those reported in other ruthenium(II)-bromide complexes such as [Ru₂Br₂(pz)(py)₈][PF₆]₂.2DMF (pz = pyrazine, py = pyridine) [av. 2.5524 (4) Å] (Mirza et al., 2003) and trans-[RuBr(py)₄C(CN)₃] [2.5453 (12) Å] (Zhang et al., 2006). Two Br atoms are trans disposed as indicated by the Br—Ru—Br bond angle of 180°, as a result of symmetry requirements. Similar case was found in analogous complex trans-[RuCl₂(py)₄] (Wong & Lau, 1994).

Related literature

For background to ruthenium complexes: see: Pagliaro et al. (2005); van Rijt & Sadler (2009); Wu et al. (2009); Zhang et al. (2005). For related structures, see: Mirza et al. (2003); Wong & Lau (1994); Zhang et al. (2006). For a description of the Cambridge Structural Database, see: Allen (2002).

S2. Experimental

To a THF solution (10 ml) of RuCl₂(DMSO)₄ (97 mg, 0.2 mmol) was added pyridine (63 mg, 0.8 mmol) and Br₂ (32 mg, 0.2 mmol) under a nitrogen atmosphere. The reaction mixture was refluxed for 2 h, developing red. The solvent was evaporated in vacuo and the residue was washed with hexane. Recrystallization from CH₂Cl₂/hexane afforded red crystals of the title complex within two days (yield: 75 mg, 65 % based on Ru). Analysis, calculated for C₂₀H₂₀Br₂N₄Ru: C 41.61, H 3.49, N 9.70%; found: C 41.53, H 3.44, N 9.63%.

S3. Refinement

H atoms were placed in geometrically idealized positions and refined as riding atoms, with C—H = 0.93 Å and with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. The molecular structure of the title compound, showing one of the two independent molecules. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: (A) x, 1/4-y, 1/4-z; (B) 1/4-x, y, 1/4-z; (C) 1/4-x, 1/4-y, z.]
	Fig. 2. Packing diagram of the title compound in a unit cell, viewed along the c axis.

trans-Dibromidotetrakis(pyridine-κN)ruthenium(II)

Crystal data

[RuBr2(C5H5N)4]	F(000) = 4512
Mr = 577.29	Dx = 1.781 Mg m^−3
Orthorhombic, Fddd	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -F 2uv 2vw	Cell parameters from 2149 reflections
a = 16.830 (4) Å	θ = 2.2–26.4°
b = 22.032 (5) Å	µ = 4.45 mm^−1
c = 23.221 (5) Å	T = 296 K
V = 8610 (3) Å^3	Block, red
Z = 16	0.22 × 0.18 × 0.13 mm

Data collection

Bruker APEXII CCD diffractometer	2430 independent reflections
Radiation source: fine-focus sealed tube	1631 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.034
ϕ and ω scans	θmax = 27.5°, θmin = 3.0°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −21→21
Tmin = 0.441, Tmax = 0.595	k = −28→28
13382 measured reflections	l = −29→26

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)] = 0.025	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.069	H-atom parameters constrained
S = 1.04	w = 1/[σ^2(Fo^2) + (0.0292P)^2 + 11.6805P] where P = (Fo^2 + 2Fc^2)/3
2430 reflections	(Δ/σ)max < 0.001
125 parameters	Δρmax = 0.58 e Å^−3
0 restraints	Δρmin = −0.34 e Å^−3

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.

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 > 2sigma(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.

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

	x	y	z	Uiso*/Ueq
Ru1	0.1250	0.1250	0.1250	0.03562 (11)
Ru2	0.6250	0.1250	0.1250	0.03634 (11)
Br1	0.1250	0.009537 (19)	0.1250	0.05758 (14)
Br2	0.6250	0.1250	0.015713 (18)	0.06143 (15)
N1	0.03782 (12)	0.12460 (9)	0.18885 (9)	0.0409 (5)
N2	0.71241 (13)	0.19195 (10)	0.12552 (9)	0.0428 (5)
C1	−0.02375 (16)	0.08600 (14)	0.18763 (12)	0.0513 (7)
H1	−0.0280	0.0594	0.1567	0.062*
C2	−0.08052 (18)	0.08388 (16)	0.22953 (14)	0.0643 (9)
H2	−0.1223	0.0564	0.2268	0.077*
C3	−0.0757 (2)	0.12230 (16)	0.27562 (15)	0.0664 (9)
H3	−0.1137	0.1216	0.3047	0.080*
C4	−0.01284 (18)	0.16198 (15)	0.27768 (13)	0.0565 (8)
H4	−0.0077	0.1887	0.3084	0.068*
C5	0.04201 (16)	0.16198 (13)	0.23442 (11)	0.0463 (6)
H5	0.0842	0.1891	0.2366	0.056*
C6	0.77437 (16)	0.19016 (13)	0.16161 (13)	0.0513 (7)
H6	0.7783	0.1577	0.1870	0.062*
C7	0.83202 (18)	0.23371 (16)	0.16297 (15)	0.0655 (9)
H7	0.8740	0.2304	0.1888	0.079*
C8	0.8280 (2)	0.28178 (15)	0.12661 (16)	0.0721 (10)
H8	0.8670	0.3117	0.1269	0.086*
C9	0.76494 (19)	0.28493 (15)	0.08948 (16)	0.0656 (9)
H9	0.7601	0.3175	0.0642	0.079*
C10	0.70898 (16)	0.23981 (13)	0.08982 (13)	0.0509 (7)
H10	0.6667	0.2424	0.0642	0.061*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ru1	0.0287 (2)	0.0399 (2)	0.0383 (2)	0.000	0.000	0.000
Ru2	0.0285 (2)	0.0431 (2)	0.0374 (2)	0.000	0.000	0.000
Br1	0.0600 (3)	0.0459 (2)	0.0668 (3)	0.000	−0.0158 (2)	0.000
Br2	0.0616 (3)	0.0806 (3)	0.0421 (2)	−0.0070 (2)	0.000	0.000
N1	0.0331 (11)	0.0465 (12)	0.0430 (12)	−0.0042 (10)	−0.0006 (9)	0.0007 (10)
N2	0.0326 (11)	0.0461 (12)	0.0497 (13)	0.0005 (9)	−0.0006 (10)	0.0022 (11)
C1	0.0398 (15)	0.0614 (18)	0.0526 (17)	−0.0119 (14)	−0.0014 (13)	0.0002 (14)
C2	0.0449 (18)	0.081 (2)	0.067 (2)	−0.0174 (16)	0.0047 (15)	0.0060 (18)
C3	0.0495 (18)	0.091 (2)	0.0590 (19)	−0.0018 (18)	0.0172 (15)	0.0106 (18)
C4	0.0482 (17)	0.072 (2)	0.0490 (17)	0.0020 (15)	0.0079 (13)	−0.0041 (15)
C5	0.0392 (15)	0.0486 (16)	0.0512 (17)	−0.0019 (12)	0.0030 (12)	−0.0028 (13)
C6	0.0382 (15)	0.0530 (17)	0.0627 (19)	0.0023 (13)	−0.0086 (14)	−0.0006 (14)
C7	0.0407 (17)	0.068 (2)	0.088 (2)	−0.0039 (15)	−0.0146 (17)	−0.0092 (18)
C8	0.0504 (19)	0.053 (2)	0.112 (3)	−0.0150 (15)	−0.001 (2)	−0.004 (2)
C9	0.0528 (19)	0.056 (2)	0.088 (2)	−0.0023 (15)	0.0069 (18)	0.0133 (18)
C10	0.0380 (15)	0.0549 (18)	0.0597 (18)	−0.0009 (13)	0.0018 (13)	0.0077 (14)

Geometric parameters (Å, º)

Ru1—N1^i	2.086 (2)	C1—H1	0.9300
Ru1—N1^ii	2.086 (2)	C2—C3	1.367 (5)
Ru1—N1	2.086 (2)	C2—H2	0.9300
Ru1—N1^iii	2.086 (2)	C3—C4	1.373 (4)
Ru1—Br1	2.5439 (7)	C3—H3	0.9300
Ru1—Br1^ii	2.5439 (7)	C4—C5	1.364 (4)
Ru2—N2^iv	2.083 (2)	C4—H4	0.9300
Ru2—N2	2.083 (2)	C5—H5	0.9300
Ru2—N2^i	2.083 (2)	C6—C7	1.365 (4)
Ru2—N2^v	2.083 (2)	C6—H6	0.9300
Ru2—Br2	2.5378 (7)	C7—C8	1.356 (5)
Ru2—Br2^v	2.5378 (7)	C7—H7	0.9300
N1—C1	1.341 (3)	C8—C9	1.370 (5)
N1—C5	1.343 (3)	C8—H8	0.9300
N2—C6	1.339 (3)	C9—C10	1.369 (4)
N2—C10	1.342 (3)	C9—H9	0.9300
C1—C2	1.365 (4)	C10—H10	0.9300
N1^i—Ru1—N1^ii	179.52 (12)	C6—N2—C10	116.3 (2)
N1^i—Ru1—N1	90.60 (12)	C6—N2—Ru2	122.20 (18)
N1^ii—Ru1—N1	89.40 (12)	C10—N2—Ru2	121.48 (18)
N1^i—Ru1—N1^iii	89.40 (12)	N1—C1—C2	123.2 (3)
N1^ii—Ru1—N1^iii	90.60 (12)	N1—C1—H1	118.4
N1—Ru1—N1^iii	179.52 (12)	C2—C1—H1	118.4
N1^i—Ru1—Br1	90.24 (6)	C1—C2—C3	119.7 (3)
N1^ii—Ru1—Br1	90.24 (6)	C1—C2—H2	120.2
N1—Ru1—Br1	89.76 (6)	C3—C2—H2	120.2
N1^iii—Ru1—Br1	89.76 (6)	C2—C3—C4	117.9 (3)
N1^i—Ru1—Br1^ii	89.76 (6)	C2—C3—H3	121.1
N1^ii—Ru1—Br1^ii	89.76 (6)	C4—C3—H3	121.1
N1—Ru1—Br1^ii	90.24 (6)	C5—C4—C3	119.7 (3)
N1^iii—Ru1—Br1^ii	90.24 (6)	C5—C4—H4	120.2
Br1—Ru1—Br1^ii	180.0	C3—C4—H4	120.2
N2^iv—Ru2—N2	179.34 (11)	N1—C5—C4	123.0 (3)
N2^iv—Ru2—N2^i	89.84 (12)	N1—C5—H5	118.5
N2—Ru2—N2^i	90.16 (12)	C4—C5—H5	118.5
N2^iv—Ru2—N2^v	90.16 (12)	N2—C6—C7	123.2 (3)
N2—Ru2—N2^v	89.84 (12)	N2—C6—H6	118.4
N2^i—Ru2—N2^v	179.34 (11)	C7—C6—H6	118.4
N2^iv—Ru2—Br2	90.33 (6)	C8—C7—C6	120.0 (3)
N2—Ru2—Br2	90.33 (6)	C8—C7—H7	120.0
N2^i—Ru2—Br2	89.67 (6)	C6—C7—H7	120.0
N2^v—Ru2—Br2	89.67 (6)	C7—C8—C9	118.0 (3)
N2^iv—Ru2—Br2^v	89.67 (6)	C7—C8—H8	121.0
N2—Ru2—Br2^v	89.67 (6)	C9—C8—H8	121.0
N2^i—Ru2—Br2^v	90.33 (6)	C10—C9—C8	119.5 (3)
N2^v—Ru2—Br2^v	90.33 (6)	C10—C9—H9	120.2
Br2—Ru2—Br2^v	180.0	C8—C9—H9	120.2
C1—N1—C5	116.5 (2)	N2—C10—C9	123.0 (3)
C1—N1—Ru1	122.09 (18)	N2—C10—H10	118.5
C5—N1—Ru1	121.38 (17)	C9—C10—H10	118.5

Symmetry codes: (i) x, −y+1/4, −z+1/4; (ii) −x+1/4, −y+1/4, z; (iii) −x+1/4, y, −z+1/4; (iv) −x+5/4, −y+1/4, z; (v) −x+5/4, y, −z+1/4.