Mg₂Ru₂Cl₁₀O·16H₂O

Mg₂Ru₂Cl₁₀O·16H₂O {dimagnesium μ-oxo-bis­[penta­chloro­ruthenate(IV)] hexa­deca­hydrate} crystallizes in the monoclinic system (space group P2₁/c). The structure consists of layers of [Ru₂Cl₁₀O]⁴⁻ anions, [Mg(H₂O)₆]²⁺ cations and water mol­ecules stacked along the a axis. Only the O atom bonded to Ru occupies the 2a site with symmetry. All the other atoms occupy general 4e sites. The crystal structure is stabilized by O—H...O and O—H...Cl inter­actions.

S1. Comment

As part of an ongoing study of ruthenium materials in high oxidation states, the chemistry of ruthenium chlorides, fluorides and oxide fluorides is of interest. These materials are also of some value to the nuclear industry (Bourgeois & Cochet-Muchy, 1971).

The structure of Mg₂Ru₂Cl₁₀O.16H₂O presented here is the first example of a salt containing the Ru^IV oxychloride anion together with magnesium. Interestingly, few other derivatives of [Ru₂Cl₁₀O]⁴⁻ are known. The only previous structure reports are for K₄Ru₂Cl₁₀O (Deloume et al., 1979) and Cs₄Ru₂Cl₁₀O (Santana Da Silva et al., 1999) where Ru^IV is present with anhydrous alkali ions. One goal of the present work was therefore to examine the nature of the interactions between the [Ru₂Cl₁₀O]⁴⁻ anion and hydrated cations capable of forming hydrogen bonds.

The asymmetric unit contains one [Ru₂Cl₁₀O]⁴⁻ anion, one [Mg(H₂O)₆]²⁺ cation and two water molecules (Fig. 1). The overall structure consists of layers stacked along the a direction, with [Ru₂Cl₁₀O]⁴⁻ dimeric units bridging adjacent layers (Fig. 2). The Ru atom resides in a distorted octahedron of one O and five Cl atoms, with an average Ru—Cl distance of 2.362 Å, similar to that in K₄Ru₂Cl₁₀O (2.362 Å), Cs₄Ru₂Cl₁₀O (2.357 Å) and K₄Ru₂Cl₁₀O·H₂O (2.360 Å). As expected, the Ru—O distance compares well with those reported for Cs₄Ru₂Cl₁₀O (1.791 Å), K₄Ru₂Cl₁₀O (1.800 Å) and K₄Ru₂Cl₁₀O·H₂O (1.797 Å). In the latter case, the structure was first determined (Mathieson et al., 1952) from a zero-level Weissenberg photograph for the formula K₄Ru₂Cl₁₀O. H₂O. A subsequent fully anisotropic refinement (R = 0.034 for 245 measured reflections) has shown that there is, in fact, no water molecule in the structure (Deloume et al., 1979). The correct formula is therefore K₄Ru₂Cl₁₀O.

The Mg²⁺ ion is surrounded by six water molecules via Mg²⁺—OH₂ ion-dipole interactions. The Mg—O distances (average Mg—O = 2.057 Å) are longer than the values reported for magnesium bis(triazide) hexahydrate (average Mg—O = 2.024 Å; Mautner & Krischner, 1986), and similar to those in [Mg(H₂O)₆](C₁₄H₁₀Cl₂NO₂).22H₂O (average Mg—O = 2.058 Å), where the Mg²⁺ ion is also hexahydrated (Castellari et al., 1999).

Two types of intermolecular interactions are present in the structure, including O—H···O hydrogen bonds and O—H···Cl dipole–dipole interactions that contribute to hold cations and anions together. The presence of water molecules in the structure results in the presence of additional hydrogen bonds (Table 2 and Fig. 3). Five O—H···O hydrogen bonds are formed by the two water molecules that ensure the cohesion between the [Mg(H₂O)₆]²⁺ ions located in the same layer. The environment of the [Ru₂Cl₁₀O]⁴⁻ anion contains twelve O—H···Cl dipole–dipole interactions between the anion and the water molecules. Overall, the various interactions bridge the rutenate anions within and between layers and form cavities occupied by the [Mg(H₂O)₆]²⁺ cations.

S2. Experimental

The title compound was crystallized from a supersaturated hydrochloric acid solution (50%, 5 ml) prepared using doubly distilled water and a mixture of ruthenium(III) chloride trihydrate (2.61 g) and magnesium chloride (0.95 g) in a 1:1 ratio. Supersaturation was obtained by gentle warming of the solution. Thin, brown needle-shaped single crystals of Mg₂Ru₂Cl₁₀O.16H₂O were obtained at ambient temperature by slow evaporation of the solution.

S3. Refinement

H atoms were fixed by geometric constraints using HFIX and allowed to ride on the attached O atom (O—H = 0.92–0.99 Å). CIF suggests that these atoms were refined with distance restraints applied, not as riding. Please check all values in Table 2; many of the O—H distances do not match the geom_bond_distance values in CIF.

Computing details

Data collection: COLLECT (Nonius, 1997); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: SCALEPACK and DENZO (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997) and ATOMS (Dowty, 1995); software used to prepare material for publication: WinGX (Farrugia, 1999) and PARST (Nardelli, 1995).

Figures

Figure 1. The asymmetric unit of Mg2Ru2Cl10O.16H2O, with 50% probability displacement ellipsoids. Figure 2. The structure of Mg2Ru2Cl10O.16H2O, viewed perpendicular to the (100) plane. Figure 3. The O—H.·Cl dipole–dipole interactions (blue lines) and O—H.·O hydrogen bonds (red lines) in the title compound.

dimagnesium µ-oxo-bis(pentachlororuthenate(IV) hexadecahydrate

Crystal data

Mg2Ru2Cl10O·16H2O	F(000) = 900
Mr = 906.88	Dx = 2.112 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 4491 reflections
a = 8.256 (2) Å	θ = 2.3–26.4°
b = 16.343 (3) Å	µ = 2.09 mm^−1
c = 10.647 (5) Å	T = 173 K
β = 95.499 (3)°	Needle, brown
V = 1430.0 (8) Å^3	0.45 × 0.06 × 0.03 mm
Z = 2

Data collection

Nonius KappaCCD diffractometer	2918 independent reflections
Radiation source: fine-focus sealed tube	2295 reflections with I > 2σ(I)
Detector resolution: 9 pixels mm^-1	Rint = 0.038
ω or ϕ scans?	θmax = 26.4°, θmin = 2.3°
Absorption correction: part of the refinement model (ΔF) (Sheldrick, 1990)	h = −9→10
Tmin = 0.760, Tmax = 0.939	k = −20→18
8087 measured reflections	l = −11→13

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)] = 0.028	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.063	H atoms treated by a mixture of independent and constrained refinement
S = 1.04	w = 1/[σ^2(Fo^2) + (0.0098P)^2 + 0.1594P] where P = (Fo^2 + 2Fc^2)/3
2918 reflections	(Δ/σ)max = 0.002
190 parameters	Δρmax = 0.58 e Å^−3
16 restraints	Δρmin = −0.66 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Ru	0.46786 (3)	0.439501 (13)	0.36057 (2)	0.01211 (9)
Cl1	0.44264 (11)	0.55535 (4)	0.22846 (8)	0.0223 (2)
Cl2	0.74948 (10)	0.43557 (4)	0.33572 (8)	0.01764 (19)
Cl3	0.18124 (10)	0.43860 (4)	0.36637 (8)	0.01985 (19)
Cl4	0.42362 (10)	0.35620 (5)	0.18105 (8)	0.0246 (2)
Cl5	0.49101 (10)	0.31640 (4)	0.47910 (8)	0.0210 (2)
Mg	0.01007 (12)	0.18896 (5)	0.25193 (10)	0.0173 (3)
O1W	0.0345 (3)	0.30061 (12)	0.1593 (2)	0.0222 (6)
H11W	0.087 (4)	0.3393 (16)	0.215 (3)	0.033*
H21W	−0.067 (3)	0.3217 (17)	0.120 (3)	0.033*
O2W	0.1570 (3)	0.22248 (14)	0.4098 (2)	0.0308 (6)
H12W	0.264 (3)	0.2452 (19)	0.416 (4)	0.046*
H22W	0.122 (4)	0.227 (2)	0.493 (2)	0.046*
O3W	0.2037 (3)	0.14318 (14)	0.1661 (3)	0.0326 (6)
H13W	0.204 (5)	0.0980 (16)	0.110 (3)	0.049*
H23W	0.304 (3)	0.1677 (19)	0.204 (3)	0.049*
O4W	−0.0214 (3)	0.07874 (13)	0.3412 (2)	0.0247 (6)
H14W	0.074 (3)	0.0545 (17)	0.386 (3)	0.037*
H24W	−0.084 (4)	0.0402 (17)	0.289 (3)	0.037*
O5W	−0.1394 (3)	0.15077 (13)	0.0987 (2)	0.0280 (6)
H15W	−0.117 (4)	0.1083 (16)	0.041 (3)	0.042*
H25W	−0.254 (2)	0.151 (2)	0.105 (4)	0.042*
O6W	−0.1955 (3)	0.23270 (13)	0.3223 (2)	0.0259 (6)
H16W	−0.212 (4)	0.2876 (12)	0.336 (3)	0.039*
H26W	−0.234 (4)	0.2079 (18)	0.394 (2)	0.039*
O7W	−0.2495 (3)	0.35047 (13)	0.0389 (2)	0.0262 (6)
H17W	−0.250 (4)	0.4089 (11)	0.030 (3)	0.039*
H27W	−0.339 (3)	0.3416 (19)	0.088 (3)	0.039*
O8W	−0.2682 (3)	0.52003 (14)	0.0458 (2)	0.0288 (6)
H18W	−0.305 (4)	0.5504 (17)	−0.031 (2)	0.043*
H28W	−0.349 (4)	0.532 (2)	0.102 (3)	0.043*
O1	0.5	0.5	0.5	0.0114 (6)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ru	0.01097 (16)	0.01256 (15)	0.01243 (15)	0.00045 (10)	−0.00084 (11)	−0.00163 (10)
Cl1	0.0258 (5)	0.0221 (4)	0.0186 (5)	0.0045 (3)	−0.0011 (4)	0.0052 (3)
Cl2	0.0122 (4)	0.0229 (4)	0.0179 (5)	0.0013 (3)	0.0016 (3)	−0.0001 (3)
Cl3	0.0115 (4)	0.0212 (4)	0.0265 (5)	0.0007 (3)	0.0000 (4)	−0.0031 (3)
Cl4	0.0216 (5)	0.0306 (4)	0.0212 (5)	−0.0010 (4)	0.0004 (4)	−0.0095 (4)
Cl5	0.0202 (5)	0.0153 (4)	0.0272 (5)	0.0002 (3)	0.0004 (4)	0.0036 (3)
Mg	0.0157 (6)	0.0175 (6)	0.0185 (7)	−0.0006 (5)	0.0002 (5)	−0.0001 (4)
O1W	0.0229 (15)	0.0178 (12)	0.0251 (15)	−0.0042 (10)	−0.0024 (11)	0.0007 (10)
O2W	0.0336 (17)	0.0353 (13)	0.0220 (15)	−0.0166 (12)	−0.0054 (13)	−0.0003 (12)
O3W	0.0257 (15)	0.0356 (15)	0.0377 (18)	0.0058 (12)	0.0094 (13)	−0.0045 (12)
O4W	0.0214 (15)	0.0203 (12)	0.0315 (16)	−0.0034 (10)	−0.0022 (12)	0.0038 (10)
O5W	0.0295 (15)	0.0283 (13)	0.0246 (15)	0.0005 (11)	−0.0055 (12)	−0.0052 (11)
O6W	0.0276 (15)	0.0206 (12)	0.0320 (16)	0.0053 (11)	0.0150 (12)	0.0033 (11)
O7W	0.0262 (15)	0.0251 (12)	0.0278 (15)	0.0016 (11)	0.0056 (12)	0.0014 (11)
O8W	0.0271 (16)	0.0366 (14)	0.0221 (16)	−0.0015 (12)	−0.0016 (12)	−0.0002 (11)
O1	0.0093 (16)	0.0116 (14)	0.0131 (17)	0.0017 (12)	−0.0007 (13)	0.0006 (12)

Geometric parameters (Å, º)

Ru—O1	1.7822 (6)	O1W—H21W	0.960 (18)
Ru—Cl4	2.3464 (11)	O7W—H17W	0.959 (18)
Ru—Cl1	2.3559 (9)	O7W—H27W	0.959 (18)
Ru—Cl2	2.3660 (10)	O6W—H16W	0.921 (18)
Ru—Cl5	2.3728 (9)	O6W—H26W	0.950 (18)
Ru—Cl3	2.3731 (10)	O2W—H12W	0.957 (18)
Mg—O5W	2.047 (3)	O2W—H22W	0.964 (18)
Mg—O6W	2.048 (2)	O3W—H13W	0.949 (18)
Mg—O2W	2.051 (3)	O3W—H23W	0.974 (19)
Mg—O3W	2.056 (3)	O5W—H15W	0.954 (18)
Mg—O4W	2.065 (2)	O5W—H25W	0.954 (18)
Mg—O1W	2.093 (2)	O1—Ru^i	1.7822 (6)
O4W—H14W	0.968 (18)	O8W—H18W	0.983 (18)
O4W—H24W	0.959 (18)	O8W—H28W	0.958 (18)
O1W—H11W	0.946 (18)
O1—Ru—Cl4	178.14 (2)	O6W—Mg—O4W	89.48 (9)
O1—Ru—Cl1	92.81 (3)	O2W—Mg—O4W	86.93 (10)
O1—Ru—Cl5	91.68 (3)	O3W—Mg—O4W	91.41 (10)
O1—Ru—Cl3	92.92 (2)	O5W—Mg—O6W	86.60 (11)
O1—Ru—Cl2	92.22 (2)	Mg—O1W—H11W	110 (2)
Cl1—Ru—Cl2	89.24 (3)	Mg—O1W—H21W	113.5 (19)
Cl1—Ru—Cl5	175.50 (3)	H11W—O1W—H21W	111 (3)
Cl1—Ru—Cl3	89.38 (3)	H17W—O7W—H27W	102 (3)
Cl2—Ru—Cl3	174.73 (3)	Mg—O2W—H12W	129 (2)
Cl2—Ru—Cl5	90.37 (3)	Mg—O2W—H22W	125 (2)
Cl4—Ru—Cl5	86.54 (4)	H12W—O2W—H22W	105 (3)
Cl4—Ru—Cl1	88.97 (4)	Mg—O3W—H13W	128 (2)
Cl4—Ru—Cl2	88.34 (3)	Mg—O3W—H23W	110 (2)
Cl4—Ru—Cl3	86.55 (3)	H13W—O3W—H23W	122 (3)
Cl5—Ru—Cl3	90.61 (3)	Mg—O4W—H14W	116.8 (19)
O5W—Mg—O1W	88.18 (10)	Mg—O4W—H24W	113 (2)
O6W—Mg—O1W	89.34 (9)	H14W—O4W—H24W	113 (3)
O2W—Mg—O1W	94.43 (10)	Mg—O5W—H15W	126 (2)
O3W—Mg—O1W	89.65 (10)	Mg—O5W—H25W	118 (2)
O4W—Mg—O1W	178.25 (11)	H15W—O5W—H25W	108 (3)
O5W—Mg—O2W	177.37 (10)	Mg—O6W—H16W	123 (2)
O6W—Mg—O2W	93.02 (11)	Mg—O6W—H26W	120 (2)
O5W—Mg—O3W	88.27 (11)	H16W—O6W—H26W	103 (3)
O6W—Mg—O3W	174.80 (12)	H18W—O8W—H28W	104 (3)
O2W—Mg—O3W	92.14 (12)	Ru^i—O1—Ru	180
O5W—Mg—O4W	90.46 (10)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H11W···Cl3	0.94 (3)	2.37 (3)	3.302 (3)	172 (3)
O1W—H21W···O7W	0.96 (3)	1.73 (3)	2.688 (4)	174 (3)
O2W—H12W···Cl5	0.95 (3)	2.25 (3)	3.180 (3)	164 (3)
O2W—H22W···O1W^ii	0.96 (2)	2.03 (2)	2.956 (3)	162 (3)
O3W—H13W···Cl2^iii	0.95 (3)	2.74 (3)	3.415 (3)	129 (2)
O3W—H13W···Cl3^iv	0.95 (3)	2.65 (3)	3.448 (4)	142 (2)
O3W—H23W···Cl1^iii	0.97 (3)	2.82 (3)	3.349 (3)	115 (2)
O4W—H14W···O8W^v	0.97 (3)	1.79 (3)	2.745 (4)	171 (3)
O4W—H24W···Cl3^v	0.96 (3)	2.43 (3)	3.363 (3)	166 (3)
O5W—H15W···Cl2^vi	0.96 (3)	2.46 (3)	3.191 (3)	133 (2)
O5W—H25W···Cl5^vi	0.96 (2)	2.44 (3)	3.237 (3)	140 (3)
O6W—H16W···Cl2^vii	0.92 (2)	2.44 (2)	3.351 (3)	171 (3)
O6W—H26W···O7W^ii	0.95 (2)	1.83 (2)	2.750 (3)	164 (3)
O7W—H17W···O8W	0.96 (2)	1.83 (2)	2.777 (3)	168 (3)
O7W—H27W···Cl4^vii	0.96 (3)	2.29 (3)	3.220 (3)	163 (3)
O8W—H28W···Cl1^vii	0.96 (3)	2.32 (3)	3.272 (3)	176 (3)
O8W—H18W···Cl4^viii	0.98 (2)	2.35 (3)	3.313 (3)	166 (2)

Symmetry codes: (ii) x, −y+1/2, z+1/2; (iii) −x+1, y−1/2, −z+1/2; (iv) x, −y+1/2, z−1/2; (v) −x, y−1/2, −z+1/2; (vi) x−1, −y+1/2, z−1/2; (vii) x−1, y, z; (viii) −x, −y+1, −z.