The structure of hexaaquanickel(II) bis(hypophosphite), [Ni(H
2O)
6](H
2PO
2)
2, has been determined. The crystals are prismatic. The packing of the Ni and P atoms (not the entire hypophosphite anions) is the same as in the structures of [Co(H
2O)
6](H
2PO
2)
2 and [Co
0.5Ni
0.5(H
2O)
6](H
2PO
2)
2. The Ni
II cations have a pseudo-face-centered cubic cell, with cell parameter
a 10.216 Å and tetrahedral cavities occupied by P atoms. The Ni
II cation has crystallographically imposed twofold symmetry and has an octahedral coordination sphere consisting of six water O atoms, two of which also lie on the twofold axis. The planes of oppositely coordinated water molecules are in a cross conformation. The geometry of the hypophosphite anion is close to point symmetry
mm2. The hypophosphite anions are hydrogen bonded to the coordinated water molecules.
Supporting information
The title compound was synthesized by slow evaporation of an aqueous solution of nickel(II) hypophosphite, prepared by adding a solution of hypophosphorous acid, H3PO2, to the nickel(II) carbonate hydroxide, NiCO3.nNi(OH)2.mH2O. The reaction mixture was evacuated in a vacuum to separate the carbon dioxide, CO2. The crystals were grown at 293 K in air.
The H atoms were located from a difference electron-density map and refined without constraints.
Data collection: CD4CA0 (Enraf-Nonius, 1989); cell refinement: CD4CA0; data reduction: CADDAT (Enraf-Nonius, 1989); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: SHELXL97.
Crystal data top
[Ni(H2O)6](H2PO2)2 | F(000) = 616 |
Mr = 296.78 | Dx = 1.851 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2yc | Cell parameters from 20 reflections |
a = 10.1453 (3) Å | θ = 12.5–13.0° |
b = 10.1467 (4) Å | µ = 2.15 mm−1 |
c = 10.3571 (3) Å | T = 293 K |
β = 92.632 (3)° | Prism, green |
V = 1065.05 (6) Å3 | 0.2 × 0.1 × 0.05 mm |
Z = 4 | |
Data collection top
Enraf-Nonius CAD-4 diffractometer | 1243 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.024 |
Graphite monochromator | θmax = 28.3°, θmin = 2.8° |
2θ/θ scans | h = 0→13 |
Absorption correction: empirical (using intensity measurements) (CADDAT; Enraf-Nonius, 1989) | k = 0→13 |
Tmin = 0.636, Tmax = 0.898 | l = −13→13 |
1401 measured reflections | 3 standard reflections every 60 min |
1331 independent reflections | intensity decay: none |
Refinement top
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.028 | All H-atom parameters refined |
wR(F2) = 0.081 | w = 1/[σ2(Fo2) + (0.0402P)2 + 1.2793P] where P = (Fo2 + 2Fc2)/3 |
S = 1.06 | (Δ/σ)max < 0.001 |
1331 reflections | Δρmax = 0.47 e Å−3 |
94 parameters | Δρmin = −0.42 e Å−3 |
0 restraints | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0116 (9) |
Crystal data top
[Ni(H2O)6](H2PO2)2 | V = 1065.05 (6) Å3 |
Mr = 296.78 | Z = 4 |
Monoclinic, C2/c | Mo Kα radiation |
a = 10.1453 (3) Å | µ = 2.15 mm−1 |
b = 10.1467 (4) Å | T = 293 K |
c = 10.3571 (3) Å | 0.2 × 0.1 × 0.05 mm |
β = 92.632 (3)° | |
Data collection top
Enraf-Nonius CAD-4 diffractometer | 1243 reflections with I > 2σ(I) |
Absorption correction: empirical (using intensity measurements) (CADDAT; Enraf-Nonius, 1989) | Rint = 0.024 |
Tmin = 0.636, Tmax = 0.898 | 3 standard reflections every 60 min |
1401 measured reflections | intensity decay: none |
1331 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.028 | 0 restraints |
wR(F2) = 0.081 | All H-atom parameters refined |
S = 1.06 | Δρmax = 0.47 e Å−3 |
1331 reflections | Δρmin = −0.42 e Å−3 |
94 parameters | |
Special details top
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 (Å2) top | x | y | z | Uiso*/Ueq | |
Ni1 | 0.0000 | 0.26480 (4) | 0.2500 | 0.02570 (16) | |
P1 | 0.23511 (5) | 0.01455 (5) | 0.00603 (5) | 0.02685 (17) | |
H1 | 0.292 (3) | −0.051 (3) | −0.080 (3) | 0.036 (7)* | |
H2 | 0.160 (2) | 0.089 (3) | −0.061 (2) | 0.034 (7)* | |
O1 | 0.33259 (14) | 0.10033 (15) | 0.08183 (13) | 0.0308 (3) | |
O2 | 0.15387 (14) | −0.07785 (14) | 0.08486 (14) | 0.0310 (3) | |
O1W | 0.0000 | 0.4657 (2) | 0.2500 | 0.0464 (7) | |
H1W | 0.047 (3) | 0.504 (3) | 0.293 (3) | 0.040 (8)* | |
O2W | 0.0000 | 0.0624 (2) | 0.2500 | 0.0453 (6) | |
H2W | 0.044 (3) | 0.022 (3) | 0.210 (3) | 0.058 (10)* | |
O3W | 0.02103 (19) | 0.27242 (19) | 0.44672 (16) | 0.0395 (4) | |
H3W | −0.034 (4) | 0.304 (4) | 0.489 (4) | 0.058 (10)* | |
H4W | 0.048 (3) | 0.213 (3) | 0.481 (3) | 0.039 (8)* | |
O4W | 0.20136 (18) | 0.2663 (2) | 0.2438 (2) | 0.0453 (5) | |
H5W | 0.243 (4) | 0.217 (4) | 0.208 (4) | 0.057 (10)* | |
H6W | 0.245 (3) | 0.306 (3) | 0.294 (3) | 0.042 (8)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Ni1 | 0.0267 (2) | 0.0271 (2) | 0.0236 (2) | 0.000 | 0.00420 (13) | 0.000 |
P1 | 0.0280 (3) | 0.0289 (3) | 0.0237 (3) | −0.00492 (18) | 0.00267 (19) | 0.00028 (17) |
O1 | 0.0301 (7) | 0.0309 (7) | 0.0315 (7) | −0.0065 (6) | 0.0022 (6) | −0.0014 (6) |
O2 | 0.0303 (7) | 0.0317 (7) | 0.0314 (7) | −0.0070 (6) | 0.0052 (6) | 0.0018 (6) |
O1W | 0.0612 (17) | 0.0273 (11) | 0.0482 (14) | 0.000 | −0.0255 (13) | 0.000 |
O2W | 0.0598 (16) | 0.0275 (11) | 0.0515 (15) | 0.000 | 0.0341 (13) | 0.000 |
O3W | 0.0466 (10) | 0.0470 (10) | 0.0252 (7) | 0.0250 (8) | 0.0070 (7) | 0.0037 (7) |
O4W | 0.0268 (8) | 0.0609 (12) | 0.0488 (11) | −0.0034 (8) | 0.0061 (7) | −0.0283 (9) |
Geometric parameters (Å, º) top
Ni1—O1W | 2.038 (3) | P1—H2 | 1.26 (2) |
Ni1—O2W | 2.054 (2) | O1W—H1W | 0.74 (3) |
Ni1—O3W | 2.0403 (17) | O2W—H2W | 0.74 (3) |
Ni1—O4W | 2.0469 (18) | O3W—H3W | 0.79 (4) |
P1—O1 | 1.5102 (14) | O3W—H4W | 0.75 (3) |
P1—O2 | 1.5122 (14) | O4W—H5W | 0.76 (4) |
P1—H1 | 1.27 (3) | O4W—H6W | 0.77 (3) |
| | | |
O1W—Ni1—O3W | 87.83 (5) | O3W—Ni1—O2W | 92.17 (5) |
O1W—Ni1—O3Wi | 87.83 (5) | O3Wi—Ni1—O2W | 92.17 (5) |
O3W—Ni1—O3Wi | 175.66 (11) | O4Wi—Ni1—O2W | 90.41 (6) |
O1W—Ni1—O4Wi | 89.59 (6) | O4W—Ni1—O2W | 90.41 (6) |
O3W—Ni1—O4Wi | 91.55 (8) | O1—P1—O2 | 115.90 (8) |
O3Wi—Ni1—O4Wi | 88.42 (8) | H1—P1—H2 | 102.2 (16) |
O1W—Ni1—O4W | 89.59 (6) | H1Wi—O1W—H1W | 117 (5) |
O3W—Ni1—O4W | 88.42 (8) | H2Wi—O2W—H2W | 113 (5) |
O3Wi—Ni1—O4W | 91.55 (8) | H3W—O3W—H4W | 108 (4) |
O4Wi—Ni1—O4W | 179.17 (12) | H5W—O4W—H6W | 111 (4) |
O1W—Ni1—O2W | 180 | | |
Symmetry code: (i) −x, y, −z+1/2. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1W—H1W···O1ii | 0.74 (3) | 2.00 (3) | 2.7412 (19) | 176 (3) |
O2W—H2W···O2 | 0.74 (3) | 2.03 (3) | 2.7628 (19) | 174 (4) |
O3W—H3W···O1iii | 0.79 (4) | 1.96 (4) | 2.743 (2) | 173 (4) |
O3W—H4W···O2iv | 0.75 (3) | 2.02 (3) | 2.754 (2) | 168 (3) |
O4W—H5W···O1 | 0.76 (4) | 2.01 (4) | 2.761 (2) | 169 (4) |
O4W—H6W···O2ii | 0.77 (3) | 1.98 (4) | 2.751 (2) | 174 (3) |
Symmetry codes: (ii) −x+1/2, y+1/2, −z+1/2; (iii) x−1/2, −y+1/2, z+1/2; (iv) x, −y, z+1/2. |
Experimental details
Crystal data |
Chemical formula | [Ni(H2O)6](H2PO2)2 |
Mr | 296.78 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 293 |
a, b, c (Å) | 10.1453 (3), 10.1467 (4), 10.3571 (3) |
β (°) | 92.632 (3) |
V (Å3) | 1065.05 (6) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 2.15 |
Crystal size (mm) | 0.2 × 0.1 × 0.05 |
|
Data collection |
Diffractometer | Enraf-Nonius CAD-4 diffractometer |
Absorption correction | Empirical (using intensity measurements) (CADDAT; Enraf-Nonius, 1989) |
Tmin, Tmax | 0.636, 0.898 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 1401, 1331, 1243 |
Rint | 0.024 |
(sin θ/λ)max (Å−1) | 0.667 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.028, 0.081, 1.06 |
No. of reflections | 1331 |
No. of parameters | 94 |
H-atom treatment | All H-atom parameters refined |
Δρmax, Δρmin (e Å−3) | 0.47, −0.42 |
Selected geometric parameters (Å, º) topNi1—O1W | 2.038 (3) | P1—O1 | 1.5102 (14) |
Ni1—O2W | 2.054 (2) | P1—O2 | 1.5122 (14) |
Ni1—O3W | 2.0403 (17) | P1—H1 | 1.27 (3) |
Ni1—O4W | 2.0469 (18) | P1—H2 | 1.26 (2) |
| | | |
O1W—Ni1—O3W | 87.83 (5) | O4Wi—Ni1—O4W | 179.17 (12) |
O3W—Ni1—O3Wi | 175.66 (11) | O1W—Ni1—O2W | 180 |
O1W—Ni1—O4W | 89.59 (6) | O1—P1—O2 | 115.90 (8) |
O3W—Ni1—O4W | 88.42 (8) | H1—P1—H2 | 102.2 (16) |
Symmetry code: (i) −x, y, −z+1/2. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1W—H1W···O1ii | 0.74 (3) | 2.00 (3) | 2.7412 (19) | 176 (3) |
O2W—H2W···O2 | 0.74 (3) | 2.03 (3) | 2.7628 (19) | 174 (4) |
O3W—H3W···O1iii | 0.79 (4) | 1.96 (4) | 2.743 (2) | 173 (4) |
O3W—H4W···O2iv | 0.75 (3) | 2.02 (3) | 2.754 (2) | 168 (3) |
O4W—H5W···O1 | 0.76 (4) | 2.01 (4) | 2.761 (2) | 169 (4) |
O4W—H6W···O2ii | 0.77 (3) | 1.98 (4) | 2.751 (2) | 174 (3) |
Symmetry codes: (ii) −x+1/2, y+1/2, −z+1/2; (iii) x−1/2, −y+1/2, z+1/2; (iv) x, −y, z+1/2. |
Studies of hexaaquametal(II) bis(hypophosphite)s have been reported previously by Ferrari & Colla (1937), Pédrazuela et al. (1953), Galigné & Dumas (1973) and Kuratieva et al. (2002). This paper presents the results of the single-crystal X-ray diffraction analysis of hexaaquanickel(II) bis(hypophosphite), [Ni(H2O)6](H2PO2)2. The calculated powder pattern of this compound is in good agreement with the experimental powder pattern, but is different from those of hexaaquacobalt(II) bis(hypophosphite) and hexaaquacobalt(II)/nickel(II) bis(hypophosphite) (Kuratieva et al., 2002).
The packing of the NiII cations and P atoms (not the complete hypophosphite anion) is the same as in the structures of [Co(H2O)6](H2PO2)2 and [Co0.5Ni0.5(H2O)6](H2PO2)2. The nickel cations form a pseudo-face-centered cubic cell, with cell-parameter a ≈ 10.216 Å and tetrahedral cavities occupied by P atoms. The powder pattern for this compound was reported previously by Ferrari & Colla (1937) and the compound was indexed as acubic system with an a cell parameter of 10.30 Å. The explanation for this mismatch has been discussed by Kuratieva et al. (2002).
The first coordination sphere of the NiII cation consists of six water molecules, which form a slightly distorted octahedron. The hypophosphite anions do not coordinate to the NiII cation. According to previously reported data, the average M—O distance for hexahydrated bivalent metal hypophosphites is 2.05 (1) Å for magnesium(II) (Galigné & Dumas, 1973), 2.074 (3) Å for cobalt(II) and 2.055 (2) Å for cobalt(II)/nickel(II) (Kuratieva et al., 2002). The average Ni—O distance in the present study is 2.045 (7) Å.
There is only one orientation of the coordinated water molecules. The planes of the oppositely coordinated water molecules are in a cross conformation. The first coordination sphere differs from those in [Co(H2O)6](H2PO2)2 and [Co0.5Ni0.5(H2O)6](H2PO2)2, which have one pair of oppositely coordinated water molecules with their planes in an eclipsed conformation.
The oppositely coordinated water molecules can be classified into three logical groups. The first group consists of molecules O1W and O2W [Ni—O distances of 2.038 (3) and 2.054 (2) Å, respectively]. The planes of these water molecules (i.e. consisting of the O and two H atoms of each molecule) are perpendicular to the plane formed by the O atoms of the other four coordinated water molecules and the NiII atom (basal plane). The dihedral angle between the planes of these water molecules is 86.5(?)°. The second group consists of molecules O3W and O3Wi [Ni—O distances of 2.0403 (17) Å; symmetry code: (i) −x, y, 1/2 − z]; the planes of these water molecules are tilted from the normal to the basal plane by an angle of 13.5(?)°. The third group consists of molecules O4W and O4Wi [Ni—O distances of 2.0469 (18) Å; symmetry code: (i) −x, y, 1/2 − z]; the planes of these water molecules are tilted from the normal to the basal plane by an angle of 30.1(?)° (Fig. 1 and Table 1). The planes of all the coordinated water molecules in [Co(H2O)6](H2PO2)2 {[Co0.5Ni0.5(H2O)6](H2PO2)2} are perpendicular to the basal plane.
The second coordination sphere of the NiII cation consists of eight hypophosphite anions, which are hydrogen bonded to water molecules coordinated to the NiII cation (Fig. 1). In spite of the similarities in the packing of the NiII cations and P atoms (Fig. 2), the orientation of the hypophosphite anions differs from that in the structures of [Co(H2O)6](H2PO2)2 and [Co0.5Ni0.5(H2O)6](H2PO2)2 due to distinctions in the first coordination spheres.
The geometry of the hypophosphite anion remains practically the same, with point symmetry mm2 (Naumov et al., 2001, 2002; Kuratieva et al., 2002), to the previously reported structures, with respective P—O distances and O—P—O angles of 1.507 (3) Å and 116.2 (3)° in [Mg(H2O)6](H2PO2)2 (Galigné & Dumas, 1973), 1.527 (1)/1.516 (1) Å and 115.3° in Co(H2PO2)Cl(H2O) (Marcos et al., 1991), 1.541 (2)/1.480 (2) Å and 118.7 (3)° in Ni(H2PO2)Cl(H2O) (Marcos et al., 1993), 1.5076 (13) Å and 115.74 (13)° in [Co(H2O)6](H2PO2)2, and 1.5092 (12) Å and 115.90 (11)° in [Co0.5Ni0.5(H2O)6](H2PO2)2 (Kuratieva et al., 2002) (Table 1).
Each hypophosphite O atom is hydrogen bonded to three water molecules from different complex cations (Table 2; thick dashed line in Fig. 2), while each hypophosphite H atom is surrounded by three water molecules from other (different) complex cations, and these H atoms are situated directly above the centers of the triangles formed by the O atoms of these three water molecules (thin dashed lines in Fig. 2). The distances between hypophosphite atom H1 and water atoms O1Wi, O3Wii and O4Wiii [symmetry codes: (i) 1/2 − x, 1/2 − y, −z; (ii) 1/2 − x, y − 1/2, 1/2 − z; (iii) x, −y, z − 1/2] are 2.94 (2), 2.91 (2) and 2.97 (2) Å, and between hypophosphite atom H2 and water atoms O2Wiv, O3Wv and O4Wvi [symmetry codes: (iv) −x, −y, −z; (v) −x, y, 1/2 − z; (vi) 1/2 − x, 1/2 − y, −z] are 2.92 (2), 2.90 (2) and 2.83 (2) Å [the average P—H···O bond length is 2.91 (2) Å]. This environment of the hypophosphite anion is similar to that in the structures of the hexaaquamagnesium(II), hexaaquacobalt(II) and hexaaquacobalt(II)/nickel(II) bis(hypophosphite)s.