Hexa­aqua­nickel(II) bis(p-tolyl­sulfonate)

The monoclinic (space group P2₁/n) structure of [Ni(H₂O)₆](p-H₃CC₆H₄SO₃)₂, with the octahedral cation at an inversion centre and the anion in a general position, shows a strong pseudo-orthorhombic (`Pnnm') symmetry. The structure comprises layers of hydro­philic and hydro­phobic moieties, the former connected by hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 150 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.050
• wR factor = 0.101
• Data-to-parameter ratio = 15.5

checkCIF results

No syntax errors found


 Alert Level B:



PLAT_112  Alert B ADDSYM Detects Additional (Pseudo) Symm. Elem.          m

PLAT_112  Alert B ADDSYM Detects Additional (Pseudo) Symm. Elem.          n

PLAT_113  Alert B ADDSYM suggests Pseudo/New Spacegroup ........       Pnnm


 0 Alert Level A = Potentially serious problem

 3 Alert Level B = Potential problem

 0 Alert Level C = Please check

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S1. Comment

For many purposes, including catalysis, transition metal complexes are required, containing anions which coordinate weakly or not at all. p-Toluenesulfonate (OTs) groups are commonly used, and for nickel(II), a useful starting compound is the hexaaqua complex, [Ni(H₂O)₆](OTs)₂, (I), where tosyl Ts is p-MeC₆H₄SO₂. (I) is easily prepared from the basic carbonate and the sulfonic acid. In it, the aqua ligands can be readily displaced by phosphine ligands, yielding such products as [Ni(dppe)₂](OTs)₂. In the course of our studies of Ni-based catalytic systems, we determined the crystal structure of (I).

The Ni atom is located at a crystallographic inversion centre and has an octahedral coordination; the OTs^- anion lies in a general position (Fig. 1). The crystal structure of (I) comprises intermittent layers of hydrophilic (cations and sulfonate groups, connected by a network of hydrogen bonds) and hydrophobic (tolyl groups) moieties. Structures with such layering can have unusual thermodynamic properties, making them prospective materials for thermal energy storage (Groh et al., 1990).

Structure (I) shows a strong pseudo-orthorhombic symmetry, approximating the space group Pnnm (No. 58) in the lattice setting a = 6.299, b = 24.933, c = 6.914 Å and `α = β = γ = 90°', the cation occupying a 2/m special position and the anion lying on the m plane, with the benzene ring disordered between two orientations, intersecting the plane at an acute angle. In fact, the structure could be solved and (poorly) refined in the space group Pnnm, converging at wR(F<sup>2</sup>) = 0.213 for all 1644 `independent' reflections, R = 0.107 for 1350 reflections with F² > 2σ(F²). Merging the data in the orthorhombic symmetry gives R_int = 0.27.

(I) is isomorphous with [Co(H₂O)₆](OTs)₂ (Cabaleiro-Martinez et al., 2000) and pseudo-isomorphous with a number of [Ni(H₂O)₆]X₂ salts, where X is PhSO₃ (Groh et al., 1990), p-ClC₆H₄SO₃ (Bernardinelli et al., 1991) and p-H₂C═CH—C₆H₄SO₃ (Leonard et al., 1999). The similarity of the latter structure with the rest is somewhat obscured by the fact that it has been reported in the P2₁/c setting rather than in P2₁/n, which corresponds to the reduced cell.

S2. Experimental

A mixture of Ni(CO₃)^.Ni(OH)₂^.4H₂O (II) (5.81 g, 1.2 mmol), HOTs (4.74 g, 2.5 mmol) and toluene (100 ml) was stirred. Water was removed by azeotropic distillation using a Dean–Stark apparatus under nitrogen, the solvent was removed under reduced pressure and the solid was dried in vacuo. The IR spectrum indicated the presence of unreacted (II). The mixture was stirred, the flask heated in air to 573±50 K on a Bunsen burner, whereupon HOTs melted and the reaction was brought to completion. After cooling to room temperature the solid products were washed with degassed toluene (2 × 10 ml) and then ether, dried in vacuo and dissolved in methanol. The solution was filtered to remove residual (II), and the methanol was removed from the filtrate in vacuo, yielding a pale-green solid of (I) (2.8 g, yield 56%). IR spectrum (solid), cm^-1: ν(S═O) 1184 (sym. str.), 1055 (asym. str.). Recrystallization from methanol yielded pale-green crystals suitable for X-ray study.

S3. Refinement

Csp²—H bond distances are in the range 0.91 (4)–0.97 (4) Å, and the Csp³—H distances are 0.92 (5) and 0.98 (6) Å.

Computing details

Data collection: SMART (Siemens, 1995); cell refinement: SMART; data reduction: SAINT (Siemens, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1997); software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. The cation and anion in the structure of (I). Primed atoms have been generated by the inversion centre. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. The crystal packing of (I). Dashed lines show the direction of the hydrogen bonds.

Hexaaquanickel(II) bis(p-tolylsulfonate)

Crystal data

[Ni(H2O)6](C7H7O3S)2	F(000) = 532
Mr = 509.18	Dx = 1.557 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 6.914 (1) Å	Cell parameters from 448 reflections
b = 6.299 (1) Å	θ = 10–20°
c = 24.933 (4) Å	µ = 1.14 mm^−1
β = 90.719 (15)°	T = 150 K
V = 1085.8 (3) Å^3	Prism, colourless
Z = 2	0.25 × 0.10 × 0.05 mm

Data collection

SMART 1K CCD area-detector diffractometer	2864 independent reflections
Radiation source: fine-focus sealed tube	2253 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.055
Detector resolution: 8 pixels mm^-1	θmax = 29.0°, θmin = 1.6°
ω scans	h = −8→9
Absorption correction: integration (XPREP SHELXTL; Bruker, 1997)	k = −6→8
Tmin = 0.763, Tmax = 0.945	l = −33→29
8262 measured reflections

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)] = 0.050	Hydrogen site location: difference Fourier map
wR(F^2) = 0.101	All H-atom parameters refined
S = 1.19	w = 1/[σ^2(Fo^2) + (0.0083P)^2 + 2.4432P] where P = (Fo^2 + 2Fc^2)/3
2864 reflections	(Δ/σ)max = 0.001
185 parameters	Δρmax = 0.55 e Å^−3
0 restraints	Δρmin = −0.48 e Å^−3

Special details

Experimental. The data collection nominally covered a hemisphere of reciprocal space, by a combination of 4 sets of ω scans; each set at different ϕ and/or 2θ angles and each scan (30 sec exposure) covering 0.3° in ω. Crystal to detector distance 4.5 cm. Crystal decay was monitored by repeating 50 initial frames at the end of data collection and comparing 119 duplicate reflections.

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.

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

	x	y	z	Uiso*/Ueq
Ni	0.5000	0.5000	0.0000	0.01655 (14)
S	−0.01007 (11)	0.10018 (12)	0.09502 (3)	0.01774 (17)
O1	0.2584 (4)	0.5957 (5)	0.04068 (13)	0.0389 (7)
H011	0.233 (7)	0.715 (8)	0.0493 (19)	0.054 (15)*
H012	0.187 (6)	0.519 (7)	0.0570 (16)	0.035 (11)*
O2	0.6817 (4)	0.5971 (4)	0.06173 (11)	0.0314 (6)
H021	0.790 (8)	0.518 (9)	0.064 (2)	0.074 (17)*
H022	0.728 (6)	0.723 (8)	0.0622 (18)	0.051 (14)*
O3	0.4859 (4)	0.2076 (4)	0.03275 (10)	0.0258 (5)
H031	0.589 (7)	0.158 (8)	0.0472 (18)	0.058 (15)*
H032	0.386 (7)	0.150 (7)	0.0455 (18)	0.053 (14)*
O4	−0.1902 (3)	0.0109 (4)	0.07327 (9)	0.0250 (5)
O5	0.1605 (3)	0.0066 (4)	0.07035 (8)	0.0240 (5)
O6	−0.0082 (3)	0.3329 (3)	0.09292 (9)	0.0234 (5)
C1	−0.0003 (4)	0.0274 (5)	0.16377 (12)	0.0194 (6)
C2	−0.0562 (5)	0.1690 (6)	0.20302 (14)	0.0259 (7)
H2	−0.090 (6)	0.312 (7)	0.1936 (15)	0.038 (11)*
C3	−0.0495 (5)	0.1079 (7)	0.25688 (14)	0.0304 (8)
H3	−0.077 (6)	0.211 (7)	0.2840 (17)	0.052 (13)*
C4	0.0131 (5)	−0.0932 (6)	0.27168 (13)	0.0274 (7)
C5	0.0660 (5)	−0.2344 (6)	0.23150 (14)	0.0291 (8)
H5	0.116 (5)	−0.373 (6)	0.2418 (13)	0.021 (9)*
C6	0.0603 (5)	−0.1769 (6)	0.17783 (14)	0.0257 (7)
H6	0.101 (6)	−0.271 (7)	0.1525 (16)	0.045 (12)*
C7	0.0302 (7)	−0.1585 (9)	0.32990 (16)	0.0406 (10)
H71	−0.015 (8)	−0.304 (10)	0.335 (2)	0.082 (19)*
H72	0.159 (8)	−0.145 (8)	0.3437 (19)	0.065 (15)*
H73	−0.043 (7)	−0.067 (8)	0.3499 (18)	0.054 (14)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni	0.0162 (2)	0.0104 (2)	0.0231 (3)	−0.0002 (2)	0.00174 (19)	−0.0008 (2)
S	0.0188 (3)	0.0122 (3)	0.0222 (4)	−0.0008 (3)	0.0002 (3)	0.0001 (3)
O1	0.0370 (15)	0.0158 (13)	0.065 (2)	0.0014 (12)	0.0306 (14)	0.0010 (14)
O2	0.0340 (14)	0.0158 (12)	0.0441 (15)	−0.0008 (11)	−0.0138 (12)	−0.0027 (12)
O3	0.0214 (12)	0.0161 (11)	0.0398 (14)	−0.0007 (10)	−0.0001 (11)	0.0071 (11)
O4	0.0249 (11)	0.0176 (11)	0.0322 (12)	−0.0035 (10)	−0.0082 (9)	0.0037 (11)
O5	0.0259 (11)	0.0189 (11)	0.0273 (11)	0.0012 (10)	0.0072 (9)	0.0000 (11)
O6	0.0258 (11)	0.0123 (10)	0.0320 (12)	−0.0007 (9)	−0.0007 (9)	0.0022 (10)
C1	0.0158 (13)	0.0182 (16)	0.0244 (15)	−0.0001 (12)	0.0012 (11)	0.0007 (13)
C2	0.0249 (16)	0.0234 (17)	0.0292 (17)	0.0038 (14)	−0.0009 (13)	−0.0032 (15)
C3	0.0273 (18)	0.038 (2)	0.0255 (18)	0.0070 (16)	−0.0013 (14)	−0.0064 (17)
C4	0.0196 (15)	0.041 (2)	0.0218 (16)	−0.0020 (15)	−0.0009 (12)	0.0005 (16)
C5	0.0300 (18)	0.0269 (19)	0.0303 (18)	0.0006 (15)	−0.0002 (14)	0.0059 (16)
C6	0.0303 (17)	0.0224 (17)	0.0244 (16)	0.0026 (14)	0.0029 (13)	0.0016 (15)
C7	0.038 (2)	0.057 (3)	0.0263 (19)	0.001 (2)	−0.0036 (17)	0.006 (2)

Geometric parameters (Å, º)

Ni—O3	2.018 (2)	C1—C6	1.396 (4)
Ni—O1	2.056 (3)	C2—C3	1.397 (5)
Ni—O2	2.067 (3)	C2—H2	0.96 (4)
S—O5	1.461 (2)	C3—C4	1.387 (5)
S—O4	1.465 (2)	C3—H3	0.96 (4)
S—O6	1.467 (2)	C4—C5	1.392 (5)
S—C1	1.775 (3)	C4—C7	1.512 (5)
O1—H011	0.80 (5)	C5—C6	1.386 (5)
O1—H012	0.80 (4)	C5—H5	0.97 (4)
O2—H021	0.90 (6)	C6—H6	0.91 (4)
O2—H022	0.85 (5)	C7—H71	0.98 (6)
O3—H031	0.86 (5)	C7—H72	0.96 (5)
O3—H032	0.85 (5)	C7—H73	0.92 (5)
C1—C2	1.383 (4)
O3^i—Ni—O3	180.00 (13)	Ni—O3—H031	117 (3)
O3^i—Ni—O1	88.61 (11)	Ni—O3—H032	126 (3)
O3—Ni—O1	91.39 (11)	H031—O3—H032	112 (4)
O3^i—Ni—O1^i	91.39 (11)	C2—C1—C6	120.2 (3)
O3—Ni—O1^i	88.61 (11)	C2—C1—S	120.6 (3)
O1—Ni—O1^i	180.00 (15)	C6—C1—S	119.2 (2)
O3^i—Ni—O2^i	90.04 (11)	C1—C2—C3	119.7 (3)
O3—Ni—O2^i	89.96 (11)	C1—C2—H2	120 (2)
O1—Ni—O2^i	87.94 (12)	C3—C2—H2	120 (2)
O1^i—Ni—O2^i	92.06 (12)	C4—C3—C2	120.9 (3)
O3^i—Ni—O2	89.96 (11)	C4—C3—H3	120 (3)
O3—Ni—O2	90.04 (11)	C2—C3—H3	119 (3)
O1—Ni—O2	92.06 (12)	C3—C4—C5	118.4 (3)
O1^i—Ni—O2	87.94 (12)	C3—C4—C7	121.6 (4)
O2^i—Ni—O2	180.00 (10)	C5—C4—C7	119.9 (4)
O5—S—O4	112.11 (14)	C6—C5—C4	121.5 (3)
O5—S—O6	112.38 (14)	C6—C5—H5	120 (2)
O4—S—O6	112.23 (14)	C4—C5—H5	119 (2)
O5—S—C1	106.33 (14)	C5—C6—C1	119.2 (3)
O4—S—C1	106.27 (14)	C5—C6—H6	119 (3)
O6—S—C1	107.01 (14)	C1—C6—H6	121 (3)
Ni—O1—H011	126 (3)	C4—C7—H71	111 (3)
Ni—O1—H012	125 (3)	C4—C7—H72	113 (3)
H011—O1—H012	107 (4)	H71—C7—H72	110 (4)
Ni—O2—H021	112 (3)	C4—C7—H73	108 (3)
Ni—O2—H022	121 (3)	H71—C7—H73	110 (4)
H021—O2—H022	101 (4)	H72—C7—H73	105 (4)

Symmetry code: (i) −x+1, −y+1, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H011···O5^ii	0.80 (5)	1.98 (5)	2.778 (4)	178 (5)
O1—H012···O6	0.80 (4)	2.01 (4)	2.810 (4)	175 (4)
O2—H021···O6^iii	0.90 (6)	1.95 (6)	2.816 (3)	161 (5)
O2—H022···O4^iv	0.85 (5)	1.92 (5)	2.767 (4)	171 (4)
O3—H031···O4^iii	0.86 (5)	1.89 (5)	2.741 (3)	171 (5)
O3—H032···O5	0.85 (5)	1.91 (5)	2.756 (3)	176 (5)

Symmetry codes: (ii) x, y+1, z; (iii) x+1, y, z; (iv) x+1, y+1, z.