Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801017469/ob6083sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536801017469/ob6083Isup2.hkl |
CCDC reference: 175984
The synthesis of (I) was carried out under N2 by refluxing a solution of RuCl3·3H2O (261.42 mg, 1 mmol) with zinc powder (130.71 mg, 2 mmol) in stirred acetonitrile for 2 h. The resulting mixture was vacuum filtered and the yellow solution evaporated. The yellow solid was then redissolved in a methanol/acetonitrile (1:2) mixture. Addition of a few drops of diluted HCl provided on standing for ca 4 d, light-yellow crystals suitable for X-ray analysis (yield 36%); importantly the yield can be improved by addition of ZnCl2 in a 1:4 (Zn/Ru) ratio. IR (KBr, cm-1): (br, O—H) 3500, (s, C≡N) 2325, 2296, (s, C—H) 2975, 2911. 1H NMR (D2O): δ = 2.43 (s). IR spectra were recorded in a Nicolet Magna-IR 560 spectrometer. 1H NMR spectra were recorded in a Bruker 300 MHz s pectrometer. Calculated for C12N6H23.1RuZnCl4O2.55: C 23.96, N 13.98, H 3.84%; found: C 23.99, N 13.95, H 3.51.
The water molecules in the framework are disordered and were located in three positions with different occupation factors. This disorder was modelled in an iteractive fashion by occupation factor and displacement parameter. In the interactive procedure made to optimize the refinement, we found that the best option was to fix Uiso of OW2, otherwise the Uiso parameters of the other molecules will be greatly affected. The water H atoms were not introduced. Occupation factors of 0.57 (2), 0.29 (4) and 0.55 (4) were obtained for OW1, OW2 and OW3, respectively. Stoichiometry calculations for water molecules based on occupation factors resulted in a value of 2.55 which is consistent with elemental analysis.
Homoleptic complexes of RuII with labile ligands, such as H2O (Bernhard et al., 1982), DMF (Judd et al., 1995) or CH3CN, are of great interest from the synthetic point of view, since a complete modification of the coordination sphere can be achieved through substitution with less labile ligands. These homoleptic complexes constitute an attractive alternative to the common starting material RuCl3·3H2O which is a heterogeneous, ill-defined mixture of variable oxidation-state, oxochloro and hydroxochloro, monomeric and polymeric ruthenium complexes, where the average oxidation state of the material is closer to RuIV than it is to RuIII. (Seddon & Seddon, 1984). In addition, the product obtained from RuCl3·3H2O reduction usually retains Cl as a ligand with a relatively inert Ru—Cl bond, which can be undesirable for certain applications (Gilbert et al., 1970; Evans et al., 1973). Previous studies (Schrock et al., 1974) reported the synthesis of [Ru(CH3CN)6][BF4]2 from [Ru(π-C3H5)2(norbornadiene)] in a two-step process, but no crystal structure was presented. Two other compounds with the [Ru(CH3CN)6]2+ cation are known, viz. the [Ru(CH3CN)6][7-(η6-C6Me6)-nido-7-RuB10H13]2 complex (Brown et al., 1987) and the [Ru(CH3CN)6][(C7H7O3S)2]·2H2O complex (Luginbühl et al., 1989). We report here the structure of a homoleptic complex, (I), which was obtained by reduction of RuCl3·3H2O with zinc powder in acetonitrile and further controlled recrystallization. Interestingly, the reaction yield can be improved up to 70% by addition of ZnCl2 to the recrystallization mixture (see Experimental). This fact along with the presence of tetrakis(acetonitrile)dichlororuthenium(II) in the mother liquor, evidenced by 1H NMR and IR measurements (Fogg et al., 1995), lead us to think of the involvement of an equilibrium between the [Ru(CH3CN)6][ZnCl4] and RuCl2(CH3CN)4 species.
The structure of (I) consists of discrete [Ru(CH3CN)6]2+ cationic units and [ZnCl4]2- anions along with crystallization water molecules (Fig. 1). The Ru1 atom is located in special position 6c (0,0,z) in the unit cell, presenting a threefold symmetry (Fig. 2). The Ru(CH3CN)62+ cation orientation, toward the z axis, makes only two acetonitrile molecules crystallographically independent. The RuII atom exhibits a slightly distorted octahedral coordination, with N1—Ru1—N1 angles of 89.2 (2)° and N1—Ru1—N2 angles of 90.3 (2)°, Ru1—N1 bond distances of 2.026 (6) Å and Ru1—N2 bond distances of 2.033 (6) Å. The coordinated acetonitrile molecules are linear [angles: N1—C1—C2 179.5 (9)° and N2—C3—C4 179.8 (11)°], but slightly bent with respect to the Ru atom [angles: Ru1—N2—C3 175.3 (6)° and Ru1—N1—C1 176.1 (6)°]. The resulting single signal for the equivalent acetonitriles in the 1H NMR spectra, evidences the octahedral coordination of the Ru atom. The [ZnCl4]2- anion has a distorted tetrahedral environment,with angles Cl2—Zn1—Cl1 107.44 (6)° and Cl2—Zn1—Cl2 111.42 (6)°, and bond distances Zn1—Cl1 2.293 (4) Å and Zn1—Cl2 2.259 (2) Å. Atoms Zn1 and Cl1 are also located in special position 6c (0,0,z) in the unit cell with the Zn1—Cl1 bond parallel to the z axis making two Cl atoms independent. Values found for bond distances and angles are consistent with those of previously reported complexes with the same [Ru(CH3CN)6]2+ cation or [ZnCl4]2- anion.
Data were retrieved from the April 2001 version (5.21) of the Cambridge Structural Database (Allen et al., 1991; 233 218 entries) for analogous compounds of the type [M(CH3CN)6][ZnCl4], where M is a transition metal, afforded the complexes with NiII (Sotofte et al., 1976) and VII (Chandrasekhar & Bird, 1985). These complexes crystallized in the P1 space group the the triclinic system, while (I) has a higher symmetry (R3).
Data collection: MSC/AFC Difractometer Control Software (Molecular Structure Corporation, 1993); cell refinement: MSC/AFC Difractometer Control Software; data reduction: TEXSAN (Molecular Structure Corporation, 1992); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXL97; software used to prepare material for publication: SHELXL97.
[Ru(C2H3N)6][ZnCl4]·2.55H2O | Melting point: 156 K |
Mr = 600.50 | Mo Kα radiation, λ = 0.71069 Å |
Trigonal, R3 | Cell parameters from 20 reflections |
a = 11.7436 (17) Å | θ = 26.5–36.7° |
c = 30.932 (8) Å | µ = 2.04 mm−1 |
V = 3694.4 (12) Å3 | T = 293 K |
Z = 6 | Prism, light yellow |
F(000) = 1797 | 0.32 × 0.20 × 0.14 mm |
Dx = 1.619 Mg m−3 |
Rigaku AFC-7S diffractometer | 1033 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.023 |
Graphite monochromator | θmax = 25.0°, θmin = 2.0° |
ω–2θ scans | h = −12→12 |
Absorption correction: ψ scan (North et al., 1968) | k = 0→13 |
Tmin = 0.650, Tmax = 0.751 | l = 0→36 |
1601 measured reflections | 3 standard reflections every 150 reflections |
1461 independent reflections | intensity decay: none |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.058 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.157 | H-atom parameters constrained |
S = 1.02 | w = 1/[σ2(Fo2) + (0.1002P)2] where P = (Fo2 + 2Fc2)/3 |
1461 reflections | (Δ/σ)max = 0.001 |
83 parameters | Δρmax = 2.93 e Å−3 |
0 restraints | Δρmin = −0.50 e Å−3 |
[Ru(C2H3N)6][ZnCl4]·2.55H2O | Z = 6 |
Mr = 600.50 | Mo Kα radiation |
Trigonal, R3 | µ = 2.04 mm−1 |
a = 11.7436 (17) Å | T = 293 K |
c = 30.932 (8) Å | 0.32 × 0.20 × 0.14 mm |
V = 3694.4 (12) Å3 |
Rigaku AFC-7S diffractometer | 1033 reflections with I > 2σ(I) |
Absorption correction: ψ scan (North et al., 1968) | Rint = 0.023 |
Tmin = 0.650, Tmax = 0.751 | 3 standard reflections every 150 reflections |
1601 measured reflections | intensity decay: none |
1461 independent reflections |
R[F2 > 2σ(F2)] = 0.058 | 0 restraints |
wR(F2) = 0.157 | H-atom parameters constrained |
S = 1.02 | Δρmax = 2.93 e Å−3 |
1461 reflections | Δρmin = −0.50 e Å−3 |
83 parameters |
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. |
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 > σ(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. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Ru1 | 0.3333 | 0.6667 | 0.57326 (3) | 0.0365 (3) | |
Zn1 | 0.6667 | 0.3333 | 0.60244 (4) | 0.0457 (4) | |
N1 | 0.3262 (5) | 0.5233 (5) | 0.53491 (17) | 0.0412 (12) | |
N2 | 0.1881 (6) | 0.5260 (6) | 0.61031 (17) | 0.0444 (13) | |
C1 | 0.3214 (7) | 0.4479 (7) | 0.5119 (2) | 0.0454 (16) | |
C2 | 0.3143 (8) | 0.3485 (8) | 0.4820 (3) | 0.066 (2) | |
H2A | 0.3954 | 0.3832 | 0.4662 | 0.099* | |
H2B | 0.2431 | 0.3244 | 0.4621 | 0.099* | |
H2C | 0.2998 | 0.2723 | 0.4980 | 0.099* | |
C3 | 0.1033 (7) | 0.4437 (7) | 0.6284 (2) | 0.0495 (17) | |
C4 | −0.0066 (8) | 0.3371 (8) | 0.6516 (3) | 0.075 (3) | |
H4A | −0.0305 | 0.2549 | 0.6378 | 0.112* | |
H4B | −0.0803 | 0.3512 | 0.6513 | 0.112* | |
H4C | 0.0190 | 0.3352 | 0.6810 | 0.112* | |
Cl1 | 0.6667 | 0.3333 | 0.67656 (11) | 0.0739 (11) | |
Cl2 | 0.48714 (19) | 0.3411 (2) | 0.58055 (6) | 0.0616 (6) | |
O1W | 0.1600 (16) | 0.1896 (16) | 0.5761 (5) | 0.143 (9)* | 0.57 (2) |
O2W | 0.0000 | 0.0000 | 0.574 (4) | 0.240* | 0.29 (4) |
O3W | 0.0000 | 0.0000 | 0.512 (2) | 0.24 (3)* | 0.55 (4) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Ru1 | 0.0373 (4) | 0.0373 (4) | 0.0348 (5) | 0.0186 (2) | 0.000 | 0.000 |
Zn1 | 0.0467 (6) | 0.0467 (6) | 0.0437 (8) | 0.0234 (3) | 0.000 | 0.000 |
N1 | 0.037 (3) | 0.043 (3) | 0.044 (3) | 0.020 (3) | 0.002 (2) | 0.001 (3) |
N2 | 0.049 (3) | 0.049 (3) | 0.038 (3) | 0.027 (3) | −0.004 (3) | −0.004 (3) |
C1 | 0.045 (4) | 0.054 (4) | 0.038 (3) | 0.025 (4) | −0.003 (3) | −0.004 (3) |
C2 | 0.087 (6) | 0.065 (5) | 0.064 (5) | 0.051 (5) | −0.012 (5) | −0.022 (4) |
C3 | 0.049 (4) | 0.055 (5) | 0.041 (4) | 0.023 (4) | 0.004 (3) | 0.009 (3) |
C4 | 0.058 (5) | 0.069 (6) | 0.088 (6) | 0.024 (4) | 0.016 (4) | 0.030 (5) |
Cl1 | 0.0883 (17) | 0.0883 (17) | 0.0452 (19) | 0.0442 (9) | 0.000 | 0.000 |
Cl2 | 0.0564 (12) | 0.0786 (14) | 0.0590 (12) | 0.0406 (11) | −0.0056 (9) | −0.0022 (10) |
Ru1—N1i | 2.026 (6) | N2—C3 | 1.129 (9) |
Ru1—N1ii | 2.026 (6) | C1—C2 | 1.459 (9) |
Ru1—N1 | 2.026 (6) | C3—C4 | 1.461 (10) |
Ru1—N2i | 2.033 (6) | Cl2—Zn1 | 2.2590 (19) |
Ru1—N2 | 2.033 (6) | Zn1—Cl2iii | 2.2590 (19) |
Ru1—N2ii | 2.033 (6) | Zn1—Cl2iv | 2.2590 (19) |
N1—C1 | 1.116 (8) | Zn1—Cl1 | 2.293 (4) |
N1i—Ru1—N1ii | 89.2 (2) | N2i—Ru1—N2ii | 91.3 (2) |
N1i—Ru1—N1 | 89.2 (2) | N2—Ru1—N2ii | 91.3 (2) |
N1ii—Ru1—N1 | 89.2 (2) | C1—N1—Ru1 | 176.1 (6) |
N1i—Ru1—N2i | 89.2 (2) | C3—N2—Ru1 | 175.3 (6) |
N1ii—Ru1—N2i | 90.3 (2) | N1—C1—C2 | 179.5 (9) |
N1—Ru1—N2i | 178.3 (2) | N2—C3—C4 | 179.8 (11) |
N1i—Ru1—N2 | 90.3 (2) | Cl2iii—Zn1—Cl2iv | 111.42 (6) |
N1ii—Ru1—N2 | 178.3 (2) | Cl2iii—Zn1—Cl2 | 111.42 (6) |
N1—Ru1—N2 | 89.2 (2) | Cl2iv—Zn1—Cl2 | 111.42 (6) |
N2i—Ru1—N2 | 91.3 (2) | Cl2iii—Zn1—Cl1 | 107.44 (6) |
N1i—Ru1—N2ii | 178.3 (2) | Cl2iv—Zn1—Cl1 | 107.44 (6) |
N1ii—Ru1—N2ii | 89.2 (2) | Cl2—Zn1—Cl1 | 107.44 (6) |
N1—Ru1—N2ii | 90.3 (2) |
Symmetry codes: (i) −x+y, −x+1, z; (ii) −y+1, x−y+1, z; (iii) −y+1, x−y, z; (iv) −x+y+1, −x+1, z. |
Experimental details
Crystal data | |
Chemical formula | [Ru(C2H3N)6][ZnCl4]·2.55H2O |
Mr | 600.50 |
Crystal system, space group | Trigonal, R3 |
Temperature (K) | 293 |
a, c (Å) | 11.7436 (17), 30.932 (8) |
V (Å3) | 3694.4 (12) |
Z | 6 |
Radiation type | Mo Kα |
µ (mm−1) | 2.04 |
Crystal size (mm) | 0.32 × 0.20 × 0.14 |
Data collection | |
Diffractometer | Rigaku AFC-7S |
Absorption correction | ψ scan (North et al., 1968) |
Tmin, Tmax | 0.650, 0.751 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 1601, 1461, 1033 |
Rint | 0.023 |
(sin θ/λ)max (Å−1) | 0.595 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.058, 0.157, 1.02 |
No. of reflections | 1461 |
No. of parameters | 83 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 2.93, −0.50 |
Computer programs: MSC/AFC Difractometer Control Software (Molecular Structure Corporation, 1993), MSC/AFC Difractometer Control Software, TEXSAN (Molecular Structure Corporation, 1992), SIR92 (Altomare et al., 1994), SHELXL97 (Sheldrick, 1997), SHELXL97.
Ru1—N1 | 2.026 (6) | Cl2—Zn1 | 2.2590 (19) |
Ru1—N2 | 2.033 (6) | Zn1—Cl1 | 2.293 (4) |
N1i—Ru1—N1 | 89.2 (2) | C3—N2—Ru1 | 175.3 (6) |
N1i—Ru1—N2 | 90.3 (2) | N1—C1—C2 | 179.5 (9) |
N1ii—Ru1—N2 | 178.3 (2) | N2—C3—C4 | 179.8 (11) |
N1—Ru1—N2 | 89.2 (2) | Cl2iii—Zn1—Cl2 | 111.42 (6) |
N2i—Ru1—N2 | 91.3 (2) | Cl2—Zn1—Cl1 | 107.44 (6) |
C1—N1—Ru1 | 176.1 (6) |
Symmetry codes: (i) −x+y, −x+1, z; (ii) −y+1, x−y+1, z; (iii) −y+1, x−y, z. |
Homoleptic complexes of RuII with labile ligands, such as H2O (Bernhard et al., 1982), DMF (Judd et al., 1995) or CH3CN, are of great interest from the synthetic point of view, since a complete modification of the coordination sphere can be achieved through substitution with less labile ligands. These homoleptic complexes constitute an attractive alternative to the common starting material RuCl3·3H2O which is a heterogeneous, ill-defined mixture of variable oxidation-state, oxochloro and hydroxochloro, monomeric and polymeric ruthenium complexes, where the average oxidation state of the material is closer to RuIV than it is to RuIII. (Seddon & Seddon, 1984). In addition, the product obtained from RuCl3·3H2O reduction usually retains Cl as a ligand with a relatively inert Ru—Cl bond, which can be undesirable for certain applications (Gilbert et al., 1970; Evans et al., 1973). Previous studies (Schrock et al., 1974) reported the synthesis of [Ru(CH3CN)6][BF4]2 from [Ru(π-C3H5)2(norbornadiene)] in a two-step process, but no crystal structure was presented. Two other compounds with the [Ru(CH3CN)6]2+ cation are known, viz. the [Ru(CH3CN)6][7-(η6-C6Me6)-nido-7-RuB10H13]2 complex (Brown et al., 1987) and the [Ru(CH3CN)6][(C7H7O3S)2]·2H2O complex (Luginbühl et al., 1989). We report here the structure of a homoleptic complex, (I), which was obtained by reduction of RuCl3·3H2O with zinc powder in acetonitrile and further controlled recrystallization. Interestingly, the reaction yield can be improved up to 70% by addition of ZnCl2 to the recrystallization mixture (see Experimental). This fact along with the presence of tetrakis(acetonitrile)dichlororuthenium(II) in the mother liquor, evidenced by 1H NMR and IR measurements (Fogg et al., 1995), lead us to think of the involvement of an equilibrium between the [Ru(CH3CN)6][ZnCl4] and RuCl2(CH3CN)4 species.
The structure of (I) consists of discrete [Ru(CH3CN)6]2+ cationic units and [ZnCl4]2- anions along with crystallization water molecules (Fig. 1). The Ru1 atom is located in special position 6c (0,0,z) in the unit cell, presenting a threefold symmetry (Fig. 2). The Ru(CH3CN)62+ cation orientation, toward the z axis, makes only two acetonitrile molecules crystallographically independent. The RuII atom exhibits a slightly distorted octahedral coordination, with N1—Ru1—N1 angles of 89.2 (2)° and N1—Ru1—N2 angles of 90.3 (2)°, Ru1—N1 bond distances of 2.026 (6) Å and Ru1—N2 bond distances of 2.033 (6) Å. The coordinated acetonitrile molecules are linear [angles: N1—C1—C2 179.5 (9)° and N2—C3—C4 179.8 (11)°], but slightly bent with respect to the Ru atom [angles: Ru1—N2—C3 175.3 (6)° and Ru1—N1—C1 176.1 (6)°]. The resulting single signal for the equivalent acetonitriles in the 1H NMR spectra, evidences the octahedral coordination of the Ru atom. The [ZnCl4]2- anion has a distorted tetrahedral environment,with angles Cl2—Zn1—Cl1 107.44 (6)° and Cl2—Zn1—Cl2 111.42 (6)°, and bond distances Zn1—Cl1 2.293 (4) Å and Zn1—Cl2 2.259 (2) Å. Atoms Zn1 and Cl1 are also located in special position 6c (0,0,z) in the unit cell with the Zn1—Cl1 bond parallel to the z axis making two Cl atoms independent. Values found for bond distances and angles are consistent with those of previously reported complexes with the same [Ru(CH3CN)6]2+ cation or [ZnCl4]2- anion.
Data were retrieved from the April 2001 version (5.21) of the Cambridge Structural Database (Allen et al., 1991; 233 218 entries) for analogous compounds of the type [M(CH3CN)6][ZnCl4], where M is a transition metal, afforded the complexes with NiII (Sotofte et al., 1976) and VII (Chandrasekhar & Bird, 1985). These complexes crystallized in the P1 space group the the triclinic system, while (I) has a higher symmetry (R3).