[Cu₂(HF₂)(H₂O)₈][AlF₆]·2H₂O

Abstract

The title compound, octaaqua­(hydrogendifluorido)­di­cop­per(II) hexa­fluoridoaluminate dihydrate, was obtained under hydro­thermal conditions. The structure is isotypic with that of the analogous Fe^III compound, [Cu₂(HF₂)(H₂O)₈][FeF₆]·2H₂O. The coordination sphere of the Cu^II atom is formed by one F and three water O atoms at short distances < 2 Å and is augmented by two additional water O atoms at significantly longer distances, leading to a considerably distorted octa­hedral environment. By edge-sharing, these octa­hedra form dimeric [Cu₂(HF₂)(H₂O)₈]³⁺ units that are bonded to [AlF₆]³⁻ anions ( symmetry) and to crystal lattice water mol­ecules via hydrogen bonds. Besides F—H⋯F inter­actions between the dimeric cationic units, O—H⋯F and O—H⋯O hydrogen bonds (both in part bifurcated) are observed.

Related literature

For the structure of the isotypic Fe^III analogue, see: Le Bail & Mercier (2009 ▶). For a natural compound in the Cu/Al/F/O/H system, Cu₄Al₃(OH)₁₄F₃(H₂O)₂ (mineral name khaidarkanite), see: Rastsvetaeva et al. (1997 ▶).

Experimental

Crystal data

• [Cu₂(HF₂)(H₂O)₈][AlF₆]·2H₂O

• M _r = 487.23

• Triclinic,

• a = 6.6119 (3) Å

• b = 7.3410 (3) Å

• c = 8.3174 (3) Å

• α = 107.336 (1)°

• β = 106.715 (1)°

• γ = 94.454 (1)°

• V = 363.15 (3) ų

• Z = 1

• Mo Kα radiation

• μ = 3.12 mm⁻¹

• T = 293 K

• 0.18 × 0.14 × 0.06 mm

Data collection

• Bruker SMART CCD area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2000 ▶) T _min = 0.52, T _max = 0.80

• 3899 measured reflections

• 2013 independent reflections

• 1952 reflections with I > 2σ(I)

• R _int = 0.019

Refinement

• R[F ² > 2σ(F ²)] = 0.026

• wR(F ²) = 0.072

• S = 1.08

• 2013 reflections

• 130 parameters

• 10 restraints

• H atoms treated by a mixture of independent and constrained refinement

• Δρ_max = 0.44 e Å⁻³

• Δρ_min = −0.54 e Å⁻³

Data collection: SMART (Bruker, 2000 ▶); cell refinement: SAINT (Bruker, 2000 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ATOMS for Windows (Dowty, 2006 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Selected bond lengths (Å).

Cu—F4	1.9049 (12)
Cu—O1	1.9441 (14)
Cu—O2	1.9522 (14)
Cu—O3	1.9739 (13)
Cu—O4	2.3463 (15)
Cu—O3i	2.7139 (16)
Al—F1	1.8001 (10)
Al—F2	1.8091 (11)
Al—F3	1.8209 (11)

Symmetry code: (i) .

Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H11⋯F1ii	0.87 (3)	1.74 (3)	2.6042 (17)	171 (4)
O1—H12⋯F2	0.83 (3)	1.86 (3)	2.6899 (18)	176 (4)
O2—H21⋯F1i	0.81 (3)	1.79 (3)	2.6020 (18)	172 (4)
O2—H22⋯O5iii	0.83 (3)	1.86 (3)	2.684 (2)	178 (4)
O3—H31⋯F3i	0.77 (3)	1.82 (3)	2.5877 (18)	178 (4)
O3—H32⋯F3iv	0.79 (3)	1.89 (3)	2.6700 (17)	174 (4)
O4—H41⋯F2v	0.85 (3)	1.95 (3)	2.7840 (19)	169 (4)
O4—H42⋯O4vi	0.67 (3)	2.41 (4)	2.758 (3)	115 (4)
O4—H42⋯O5iv	0.67 (3)	2.41 (4)	2.784 (2)	117 (4)
O5—H51⋯F2vii	0.75 (3)	2.14 (3)	2.8538 (19)	159 (4)
O5—H51⋯F3viii	0.75 (3)	2.50 (3)	3.072 (2)	135 (4)
O5—H52⋯F4	1.04 (3)	1.67 (3)	2.6620 (19)	158 (3)
F4—H6⋯F4v	0.9031 (13)	1.6945 (13)	2.596 (3)	175.27 (5)

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) ; (v) ; (vi) ; (vii) ; (viii) .

supplementary crystallographic information

Comment

The crystal structure (Fig. 1) of the title compound, [Cu₂(HF₂)(H₂O)₈][AlF₆].2H₂O), is isotypic with [Cu₂(HF₂)(H₂O)₈][FeF₆].2H₂O (Le Bail & Mercier, 2009). Except the Al—F distances (¯d = 1.810 Å versus 1.930 Å for the average Fe—F distance), all other interatomic distances, angles and the hydrogen bond geometry are very similar for the two structures. A detailed description of this structure has been given Le Bail & Mercier (2009).

There is one additional compound described in the Cu/Al/F/O/H system, viz the mineral khaidarkanite with formula Cu₄Al₃(OH)₁₄F₃(H₂O)₂ (Rastsvetaeva et al., 1997). The latter differs from the title compound as its structure contains distorted [Cu(OH)₅(H₂O)] octahedra, and [Al(OH)₆] and [AlF₄(H₂O)₂] octahedra as building units.

Experimental

AlF₃ and CuSO₄^.5H₂O (both Merck, p.a.) were reacted hydrothermally in a 2 M HF solution at 393 K for 4 d. Blue crystals of the title compound with mostly platy habit and up to 0.3 mm in length were obtained.

Refinement

The structure was solved using direct methods. For better comparison with the isotypic Fe^III analogue (Le Bail & Mercier, 2009), the atomic coordinates of the latter were used for the final refinement cycles. All H atoms were located from difference Fourier maps. The water H atoms were restrained to have O—H distances of 0.85 Å. Their U_iso values were refined with one common parameter. The position of the H atom of the disordered HF group (set with a site occupation factor of 1/2) was fixed during refinement, but its U_iso value was refined independently.

Figures

Fig. 1.

The crystal structure of [Cu2(HF2)(H2O)8][AlF6](H2O)2 in polyhedral representation projected along [010]. Colour key: O atoms white, F atoms green, H atoms are grey, [CuO5F] octahedra are blue, [AlF6] octahedra are red. Displacement ellipsoids are given at the 74% probability level; H atoms are displayed as spheres of arbitrary radius. Hydrogen bonds are indicated with green lines. Note that for clarity only one of the disordered H atoms bonded to the F atom is shown.

Crystal data

[Cu2(HF2)(H2O)8][AlF6]·2H2O	Z = 1
Mr = 487.23	F(000) = 244
Triclinic, P1	Dx = 2.228 Mg m−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.6119 (3) Å	Cell parameters from 3443 reflections
b = 7.3410 (3) Å	θ = 2.7–30.0°
c = 8.3174 (3) Å	µ = 3.12 mm−1
α = 107.336 (1)°	T = 293 K
β = 106.715 (1)°	Plate, blue
γ = 94.454 (1)°	0.18 × 0.14 × 0.06 mm
V = 363.15 (3) Å3

Data collection

Bruker SMART CCD area-detector diffractometer	2013 independent reflections
Radiation source: fine-focus sealed tube	1952 reflections with I > 2σ(I)
graphite	Rint = 0.019
ω scans	θmax = 30.0°, θmin = 2.7°
Absorption correction: multi-scan (SADABS; Bruker, 2000)	h = −9→9
Tmin = 0.52, Tmax = 0.80	k = −10→10
3899 measured reflections	l = −11→11

Refinement

Refinement on F2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.026	H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.072	w = 1/[σ2(Fo2) + (0.0482P)2 + 0.1517P] where P = (Fo2 + 2Fc2)/3
S = 1.08	(Δ/σ)max = 0.001
2013 reflections	Δρmax = 0.44 e Å−3
130 parameters	Δρmin = −0.54 e Å−3
10 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.059 (5)

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.

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.

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
Cu	0.60564 (3)	0.55637 (3)	0.23399 (2)	0.01836 (10)
Al	0.0000	0.0000	0.0000	0.01611 (15)
F1	0.21626 (18)	−0.02274 (17)	−0.09157 (16)	0.0272 (2)
F2	0.19296 (18)	0.12317 (17)	0.21936 (15)	0.0282 (2)
F3	−0.02395 (19)	0.23071 (16)	−0.03724 (18)	0.0278 (2)
F4	0.4323 (2)	0.5863 (2)	0.38450 (18)	0.0354 (3)
O1	0.5678 (2)	0.2833 (2)	0.2103 (2)	0.0289 (3)
O2	0.6023 (3)	0.8243 (2)	0.2410 (2)	0.0266 (3)
O3	0.7505 (2)	0.5080 (2)	0.0522 (2)	0.0248 (3)
O4	0.9127 (2)	0.6621 (2)	0.4883 (2)	0.0278 (3)
O5	0.2346 (3)	0.8900 (2)	0.4430 (2)	0.0296 (3)
H11	0.636 (6)	0.198 (5)	0.160 (5)	0.055 (3)*
H12	0.456 (5)	0.233 (5)	0.218 (5)	0.055 (3)*
H21	0.668 (6)	0.881 (5)	0.196 (5)	0.055 (3)*
H22	0.653 (6)	0.910 (5)	0.340 (4)	0.055 (3)*
H31	0.833 (6)	0.586 (5)	0.050 (5)	0.055 (3)*
H32	0.811 (6)	0.421 (5)	0.027 (5)	0.055 (3)*
H41	0.885 (6)	0.716 (5)	0.583 (4)	0.055 (3)*
H42	1.009 (5)	0.644 (5)	0.483 (5)	0.055 (3)*
H51	0.213 (6)	0.925 (5)	0.365 (4)	0.055 (3)*
H52	0.344 (6)	0.796 (5)	0.435 (5)	0.055 (3)*
H6	0.4722	0.5226	0.4629	0.026 (12)*	0.50

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Cu	0.02240 (14)	0.01519 (13)	0.02078 (14)	0.00360 (8)	0.01130 (9)	0.00657 (9)
Al	0.0176 (3)	0.0141 (3)	0.0194 (3)	0.0027 (2)	0.0093 (2)	0.0063 (2)
F1	0.0279 (5)	0.0262 (5)	0.0377 (6)	0.0082 (4)	0.0226 (5)	0.0129 (5)
F2	0.0273 (5)	0.0301 (6)	0.0225 (5)	−0.0007 (4)	0.0070 (4)	0.0049 (4)
F3	0.0304 (5)	0.0188 (5)	0.0424 (6)	0.0066 (4)	0.0175 (5)	0.0161 (5)
F4	0.0481 (7)	0.0379 (7)	0.0378 (7)	0.0205 (6)	0.0281 (6)	0.0211 (5)
O1	0.0280 (7)	0.0161 (6)	0.0471 (8)	0.0040 (5)	0.0213 (6)	0.0084 (6)
O2	0.0394 (7)	0.0176 (6)	0.0273 (6)	0.0042 (5)	0.0164 (6)	0.0091 (5)
O3	0.0284 (6)	0.0189 (6)	0.0333 (7)	0.0049 (5)	0.0200 (6)	0.0079 (5)
O4	0.0262 (6)	0.0276 (7)	0.0280 (6)	0.0050 (5)	0.0086 (5)	0.0073 (5)
O5	0.0379 (7)	0.0279 (7)	0.0266 (6)	0.0090 (6)	0.0134 (6)	0.0108 (5)

Geometric parameters (Å, °)

Cu—F4	1.9049 (12)	Al—F1	1.8001 (10)
Cu—O1	1.9441 (14)	Al—F1ii	1.8001 (10)
Cu—O2	1.9522 (14)	Al—F2ii	1.8091 (11)
Cu—O3	1.9739 (13)	Al—F2	1.8091 (11)
Cu—O4	2.3463 (15)	Al—F3ii	1.8209 (11)
Cu—O3i	2.7139 (16)	Al—F3	1.8209 (11)
Cu—Cui	3.5440 (4)	F4—F4iii	2.596 (3)
F4—Cu—O1	86.72 (6)	F4iii—F4—O1	75.78 (7)
F4—Cu—O2	90.07 (6)	Cu—F4—O5	120.66 (7)
O1—Cu—O2	172.31 (6)	F4iii—F4—O5	123.74 (8)
F4—Cu—O3	172.54 (6)	O1—F4—O5	159.76 (8)
O1—Cu—O3	91.01 (6)	Cu—F4—O2	45.67 (4)
O2—Cu—O3	91.29 (6)	F4iii—F4—O2	138.16 (10)
F4—Cu—O4	89.18 (6)	O1—F4—O2	92.70 (6)
O1—Cu—O4	97.22 (6)	O5—F4—O2	75.99 (6)
O2—Cu—O4	89.72 (6)	H11—O1—H12	113 (4)
O3—Cu—O4	98.16 (6)	Cu—O2—Cui	65.57 (4)
F4—Cu—O3i	89.91 (5)	F4—O2—Cui	93.18 (5)
O1—Cu—O3i	91.35 (6)	Cu—O2—H21	126 (3)
O2—Cu—O3i	81.64 (6)	F4—O2—H21	169 (3)
O3—Cu—O3i	83.04 (5)	Cui—O2—H21	83 (3)
O4—Cu—O3i	171.31 (5)	Cu—O2—H22	117 (3)
F1—Al—F1ii	180.00 (8)	F4—O2—H22	91 (3)
F1—Al—F2ii	90.44 (5)	Cui—O2—H22	176 (3)
F1ii—Al—F2ii	89.56 (5)	H21—O2—H22	92 (4)
F1—Al—F2	89.56 (5)	Cu—O3—Cui	96.96 (5)
F1ii—Al—F2	90.44 (5)	Cu—O3—H31	123 (3)
F2ii—Al—F2	180.0	Cui—O3—H31	107 (3)
F1—Al—F3ii	89.97 (5)	Cu—O3—H32	125 (3)
F1ii—Al—F3ii	90.03 (5)	Cui—O3—H32	106 (3)
F2ii—Al—F3ii	90.57 (6)	H31—O3—H32	97 (4)
F2—Al—F3ii	89.43 (6)	Cu—O4—H41	113 (2)
F1—Al—F3	90.03 (5)	F4—O4—H41	75 (3)
F1ii—Al—F3	89.97 (5)	Cu—O4—H42	121 (3)
F2ii—Al—F3	89.43 (6)	F4—O4—H42	156 (3)
F2—Al—F3	90.57 (6)	H41—O4—H42	126 (4)
F3ii—Al—F3	180.00 (8)	F4—O5—H51	110 (3)
Cu—F4—F4iii	109.26 (8)	H51—O5—H52	109 (3)
Cu—F4—O1	47.26 (4)

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

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H11···F1iv	0.87 (3)	1.74 (3)	2.6042 (17)	171 (4)
O1—H12···F2	0.83 (3)	1.86 (3)	2.6899 (18)	176 (4)
O2—H21···F1i	0.81 (3)	1.79 (3)	2.6020 (18)	172 (4)
O2—H22···O5v	0.83 (3)	1.86 (3)	2.684 (2)	178 (4)
O3—H31···F3i	0.77 (3)	1.82 (3)	2.5877 (18)	178 (4)
O3—H32···F3vi	0.79 (3)	1.89 (3)	2.6700 (17)	174 (4)
O4—H41···F2iii	0.85 (3)	1.95 (3)	2.7840 (19)	169 (4)
O4—H42···O4vii	0.67 (3)	2.41 (4)	2.758 (3)	115 (4)
O4—H42···O5vi	0.67 (3)	2.41 (4)	2.784 (2)	117 (4)
O5—H51···F2viii	0.75 (3)	2.14 (3)	2.8538 (19)	159 (4)
O5—H51···F3ix	0.75 (3)	2.50 (3)	3.072 (2)	135 (4)
O5—H52···F4	1.04 (3)	1.67 (3)	2.6620 (19)	158 (3)
F4—H6···F4iii	0.9031 (13)	1.6945 (13)	2.596 (3)	175.27 (5)

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