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The crystal structure of a second polymorph of CaSiF6·2H2O featuring a layered structure connected by hydrogen bonds is presented.
Keywords: calcium hexafluoridosilicate; bond-valence parameter; crystal structure; disorder; hydrogen bonding.
Supporting information
![]() | Crystallographic Information File (CIF) https://doi.org/10.1107/S2056989023009349/hb8080sup1.cif |
![]() | Structure factor file (CIF format) https://doi.org/10.1107/S2056989023009349/hb8080Isup2.hkl |
CCDC reference: 2303630
Computing details top
Calcium hexafluoridosilicate dihydrate top
Crystal data top
CaSiF6·2H2O | F(000) = 216 |
Mr = 218.20 | Dx = 2.492 Mg m−3 |
Monoclinic, P2/c | Cu Kα radiation, λ = 1.54184 Å |
a = 5.96605 (17) Å | Cell parameters from 5902 reflections |
b = 5.13977 (12) Å | θ = 7.8–75.3° |
c = 9.9308 (3) Å | µ = 12.29 mm−1 |
β = 107.275 (3)° | T = 100 K |
V = 290.78 (1) Å3 | Plate, colourless |
Z = 2 | 0.15 × 0.08 × 0.02 mm |
Data collection top
XtaLAB Synergy-S, Dualflex, Eiger2 R CdTe 1M diffractometer | 608 independent reflections |
Radiation source: micro-focus sealed X-ray tube, PhotonJet (Cu) X-ray Source | 598 reflections with I > 2σ(I) |
Mirror monochromator | Rint = 0.051 |
Detector resolution: 13.3333 pixels mm-1 | θmax = 75.4°, θmin = 7.8° |
ω scans | h = −7→7 |
Absorption correction: gaussian (CrysalisPro; Rigaku OD, 2022) | k = −6→6 |
Tmin = 0.365, Tmax = 1.000 | l = −12→12 |
8322 measured reflections |
Refinement top
Refinement on F2 | Primary atom site location: iterative |
Least-squares matrix: full | Hydrogen site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.025 | All H-atom parameters refined |
wR(F2) = 0.070 | w = 1/[σ2(Fo2) + (0.0516P)2 + 0.0488P] where P = (Fo2 + 2Fc2)/3 |
S = 1.14 | (Δ/σ)max < 0.001 |
608 reflections | Δρmax = 0.32 e Å−3 |
61 parameters | Δρmin = −0.37 e Å−3 |
0 restraints |
Special details top
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Ca1 | 0.000000 | 0.58252 (7) | 0.250000 | 0.01360 (19) | |
Si1 | 0.000000 | 0.000000 | 0.500000 | 0.0135 (2) | |
F1 | −0.06447 (16) | 0.26688 (17) | 0.39793 (9) | 0.0187 (3) | |
F2 | 0.20424 (15) | 0.17052 (18) | 0.62125 (9) | 0.0178 (2) | |
F3 | −0.19861 (16) | 0.09149 (15) | 0.58239 (10) | 0.0164 (3) | |
O1 | 0.3884 (2) | 0.4033 (2) | 0.36145 (15) | 0.0190 (3) | |
H1 | 0.378 (5) | 0.255 (6) | 0.373 (3) | 0.035 (7)* | |
H2B | 0.469 (8) | 0.483 (9) | 0.441 (5) | 0.016 (13)* | 0.49 (5) |
H2A | 0.475 (8) | 0.419 (7) | 0.318 (5) | 0.017 (13)* | 0.51 (5) |
Atomic displacement parameters (Å2) top
U11 | U22 | U33 | U12 | U13 | U23 | |
Ca1 | 0.0176 (3) | 0.0092 (3) | 0.0144 (3) | 0.000 | 0.00529 (18) | 0.000 |
Si1 | 0.0181 (3) | 0.0090 (3) | 0.0140 (3) | 0.0000 (2) | 0.0059 (2) | 0.0000 (2) |
F1 | 0.0251 (5) | 0.0124 (4) | 0.0201 (5) | 0.0025 (4) | 0.0091 (4) | 0.0041 (3) |
F2 | 0.0189 (5) | 0.0155 (4) | 0.0190 (5) | −0.0010 (3) | 0.0056 (4) | −0.0037 (3) |
F3 | 0.0201 (5) | 0.0120 (5) | 0.0185 (5) | −0.0003 (3) | 0.0080 (4) | −0.0020 (3) |
O1 | 0.0199 (6) | 0.0145 (6) | 0.0224 (6) | −0.0008 (4) | 0.0058 (5) | 0.0006 (4) |
Geometric parameters (Å, º) top
Ca1—Si1i | 3.2815 (3) | Si1—F1vi | 1.6808 (9) |
Ca1—Si1ii | 3.2815 (3) | Si1—F1 | 1.6809 (9) |
Ca1—F1 | 2.2965 (9) | Si1—F2vi | 1.6826 (9) |
Ca1—F1iii | 2.2965 (9) | Si1—F2 | 1.6827 (9) |
Ca1—F2iv | 2.3783 (9) | Si1—F3 | 1.6942 (9) |
Ca1—F2v | 2.3783 (9) | Si1—F3vi | 1.6942 (9) |
Ca1—F3iv | 2.4105 (9) | O1—H1 | 0.78 (3) |
Ca1—F3v | 2.4105 (9) | O1—H2B | 0.90 (5) |
Ca1—O1 | 2.4331 (13) | O1—H2A | 0.77 (5) |
Ca1—O1iii | 2.4331 (13) | ||
Si1ii—Ca1—Si1i | 98.328 (10) | O1—Ca1—Si1i | 112.20 (3) |
F1iii—Ca1—Si1i | 86.58 (2) | O1iii—Ca1—Si1ii | 112.20 (3) |
F1—Ca1—Si1i | 169.60 (2) | O1iii—Ca1—Si1i | 96.74 (3) |
F1iii—Ca1—Si1ii | 169.60 (2) | O1iii—Ca1—O1 | 135.49 (6) |
F1—Ca1—Si1ii | 86.58 (2) | Ca1vii—Si1—Ca1v | 180.0 |
F1—Ca1—F1iii | 90.11 (4) | F1—Si1—Ca1v | 82.60 (3) |
F1—Ca1—F2iv | 158.57 (3) | F1—Si1—Ca1vii | 97.40 (3) |
F1—Ca1—F2v | 79.82 (3) | F1vi—Si1—Ca1v | 97.40 (3) |
F1iii—Ca1—F2iv | 79.82 (3) | F1vi—Si1—Ca1vii | 82.60 (3) |
F1iii—Ca1—F2v | 158.57 (3) | F1vi—Si1—F1 | 180.0 |
F1—Ca1—F3iv | 142.32 (3) | F1vi—Si1—F2vi | 89.65 (5) |
F1—Ca1—F3v | 100.99 (3) | F1—Si1—F2vi | 90.35 (5) |
F1iii—Ca1—F3v | 142.32 (3) | F1—Si1—F2 | 89.65 (5) |
F1iii—Ca1—F3iv | 100.99 (3) | F1vi—Si1—F2 | 90.35 (5) |
F1—Ca1—O1 | 76.07 (4) | F1—Si1—F3 | 89.83 (4) |
F1iii—Ca1—O1iii | 76.07 (4) | F1—Si1—F3vi | 90.17 (4) |
F1iii—Ca1—O1 | 72.88 (4) | F1vi—Si1—F3 | 90.17 (4) |
F1—Ca1—O1iii | 72.88 (4) | F1vi—Si1—F3vi | 89.83 (4) |
F2v—Ca1—Si1ii | 29.44 (2) | F2—Si1—Ca1v | 44.00 (3) |
F2v—Ca1—Si1i | 99.95 (3) | F2—Si1—Ca1vii | 136.00 (3) |
F2iv—Ca1—Si1i | 29.44 (2) | F2vi—Si1—Ca1v | 136.00 (3) |
F2iv—Ca1—Si1ii | 99.95 (3) | F2vi—Si1—Ca1vii | 44.00 (3) |
F2iv—Ca1—F2v | 115.49 (5) | F2vi—Si1—F2 | 180.0 |
F2iv—Ca1—F3v | 77.00 (3) | F2—Si1—F3vi | 91.63 (4) |
F2v—Ca1—F3v | 58.87 (3) | F2vi—Si1—F3 | 91.63 (4) |
F2v—Ca1—F3iv | 77.00 (3) | F2—Si1—F3 | 88.37 (4) |
F2iv—Ca1—F3iv | 58.87 (3) | F2vi—Si1—F3vi | 88.37 (4) |
F2v—Ca1—O1iii | 82.87 (4) | F3—Si1—Ca1v | 45.25 (3) |
F2iv—Ca1—O1iii | 121.89 (4) | F3vi—Si1—Ca1v | 134.75 (3) |
F2iv—Ca1—O1 | 82.87 (4) | F3—Si1—Ca1vii | 134.75 (3) |
F2v—Ca1—O1 | 121.89 (4) | F3vi—Si1—Ca1vii | 45.25 (3) |
F3v—Ca1—Si1ii | 29.94 (2) | F3—Si1—F3vi | 180.0 |
F3v—Ca1—Si1i | 87.56 (2) | Si1—F1—Ca1 | 155.57 (5) |
F3iv—Ca1—Si1i | 29.94 (2) | Si1—F2—Ca1v | 106.56 (4) |
F3iv—Ca1—Si1ii | 87.56 (2) | Si1—F3—Ca1v | 104.81 (4) |
F3v—Ca1—F3iv | 91.93 (4) | Ca1—O1—H1 | 110 (2) |
F3v—Ca1—O1 | 75.09 (4) | Ca1—O1—H2B | 115 (3) |
F3v—Ca1—O1iii | 141.61 (4) | Ca1—O1—H2A | 114 (3) |
F3iv—Ca1—O1 | 141.61 (4) | H1—O1—H2B | 111 (3) |
F3iv—Ca1—O1iii | 75.09 (4) | H1—O1—H2A | 107 (3) |
O1—Ca1—Si1ii | 96.74 (3) | ||
Ca1v—Si1—F1—Ca1 | 115.56 (12) | F2vi—Si1—F1—Ca1 | −108.01 (13) |
Ca1vii—Si1—F1—Ca1 | −64.44 (12) | F2—Si1—F1—Ca1 | 71.99 (13) |
Ca1vii—Si1—F2—Ca1v | 180.000 (1) | F2vi—Si1—F3—Ca1v | −170.07 (5) |
Ca1vii—Si1—F3—Ca1v | 180.000 (1) | F2—Si1—F3—Ca1v | 9.93 (5) |
F1vi—Si1—F2—Ca1v | −100.32 (4) | F3vi—Si1—F1—Ca1 | −19.64 (13) |
F1—Si1—F2—Ca1v | 79.69 (4) | F3—Si1—F1—Ca1 | 160.36 (13) |
F1—Si1—F3—Ca1v | −79.72 (4) | F3vi—Si1—F2—Ca1v | 169.84 (5) |
F1vi—Si1—F3—Ca1v | 100.28 (4) | F3—Si1—F2—Ca1v | −10.16 (5) |
Symmetry codes: (i) −x, y+1, −z+1/2; (ii) x, y+1, z; (iii) −x, y, −z+1/2; (iv) x, −y+1, z−1/2; (v) −x, −y+1, −z+1; (vi) −x, −y, −z+1; (vii) x, y−1, z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···F3vi | 0.78 (3) | 2.19 (3) | 2.9042 (14) | 153 (3) |
O1—H2B···O1viii | 0.90 (5) | 1.98 (5) | 2.856 (3) | 167 (4) |
O1—H2A···O1ix | 0.77 (5) | 2.17 (5) | 2.902 (3) | 159 (4) |
Symmetry codes: (vi) −x, −y, −z+1; (viii) −x+1, −y+1, −z+1; (ix) −x+1, y, −z+1/2. |
Comparison of the BVS calculation results for SiIV of crystal structures
collected in Table 2 employing the new
R0 parameter
and the previously reported
parameter top
R0 | Maximum BVS | Minimum BVS | Mean BVS | Standard deviation | % of data within ± 0.2 v.u. | % of data within ± 0.1 v.u. | |
This study | 1.534 | 4.304 | 3.714 | 4.005 | 0.086 | 93.9 | 87.8 |
Brese & O'Keeffe (1991) | 1.58 | 4.860 | 4.194 | 4.522 | 0.098 | 2.0 | 0 |
Crystal structures used for the calculation of the new empirical R0
bond-valence
parameter for SiSiIV–F top
Compound | ICSD number | Reference | Si—F bond-length range (Å) | BVS for Si (R0 from Brese & O'Keeffe, 1991) | BVS for Si (new R0) |
BaSiF6 | 60882 | (Svensson et al., 1986) | 1.688 (2) | 4.481 | 3.968 |
(CH3NH3)2SiF6 | 110673 | (Conley et al., 2002) | 1.6810 (12)–1.6828 (17) | 4.559 | 4.037 |
(CH7N4)2SiF6·2H2O | 280103 | (Ross et al., 1999) | 1.6797 (9)–1.6808 (9) | 4.578 | 4.054 |
(CH8N4)SiF6 | 280102 | (Ross et al., 1999) | 1.6684 (9)–1.7043 (9) | 4.529 | 4.010 |
(C(NH2)2OH)2SiF6 | 63069 | (Gubin et al., 1988) | 1.677 (2)–1.6971 (18) | 4.513 | 3.996 |
(C(NH2)3)2SiF6 | 59237 | (Waskowska, 1997) | 1.6805 (12)–1.6833 (8) | 4.550 | 4.029 |
(C4H13N5)SiF6 | 166449 | (Gel'mbol'dt et al., 2009) | 1.657 (3)–1.698 (3) | 4.643 | 4.111 |
CaSiF6·2H2O(mP2) | Present work | 1.6808 (9)–1.6942 (9) | 4.507 | 3.991 | |
[Co(NH3)5(NO2)]SiF6 | 280030 | (Naumov et al., 1999) | 1.6769 (18)–1.6899 (13) | 4.495 | 3.981 |
CrSiF6·4H2O | 165384 | (Cotton et al., 1993) | 1.6640 (8)–1.6968 (8) | 4.546 | 4.026 |
CsLiSiF6 | 142874 | (Stoll et al., 2021) | 1.667 (2)–1.699 (2) | 4.479 | 3.966 |
[Cu(bpy)2(H2O)]SiF6·4H2O | 133607 | (Nisbet et al., 2021) | 1.6677 (10)–1.6947 (9) | 4.574 | 4.050 |
[Cu{SC(NH2)2}4]2SiF6 | 249750 | (Bowmaker et al., 2008) | 1.663 (2)–1.696 (2) | 4.585 | 4.060 |
CuSiF6·4H2O | 165385 | (Cotton et al., 1993) | 1.6686 (8)–1.6973 (9) | 4.510 | 3.993 |
CuSiF6·6H2O | 34760 | (Ray et al., 1973b) | 1.679 (5) | 4.591 | 4.066 |
1.659 (6)–1.674 (6) | 4.765 | 4.219 | |||
H2SiF6·4H2O | 40388 | (Mootz & Oellers, 1988) | 1.666 (1)–1.696 (1) | 4.553 | 4.031 |
H2SiF6·6H2O | 40389 | (Mootz & Oellers, 1988) | 1.677 (1)–1.704 (1) | 4.447 | 3.938 |
H2SiF6·9.5H2O | 40390 | (Mootz & Oellers, 1988) | 1.680 (1)–1.697 (1) | 4.454 | 3.944 |
1.684 (1)–1.706 (1) | 4.448 | 3.939 | |||
K2SiF6(cF4) | 420429 | (Kutoglu et al., 2009) | 1.6873 (16) | 4.490 | 3.975 |
K2SiF6(hP2) | 158483 | (Gramaccioli & Campostrini, 2007) | 1.681 (2)–1.689 (2) | 4.518 | 4.000 |
K2SiF6·KNO3 | 417735 | (Rissom et al., 2008) | 1.6782 (6) | 4.601 | 4.074 |
KLiSiF6 | 142875 | (Stoll et al., 2021) | 1.676 (1)–1.701 (1) | 4.495 | 3.980 |
KNaSiF6 | 71334 | (Fischer & Krämer, 1991) | 1.641 (5)–1.678 (5) | 4.860 | 4.304 |
K3Na(SiF6)(TaF7) | 122403 | (Tang et al., 2021) | 1.665 (3)–1.702 (3) | 4.558 | 4.036 |
K3Na4(BF4)(SiF6)3 | 121301 | (Bandemehr et al., 2020) | 1.650 (2)–1.699 (2) | 4.535 | 4.015 |
1.666 (2)–1.700 (1) | 4.560 | 4.038 | |||
Li2SiF6 | 425923 | (Hinteregger et al., 2014) | 1.685 (2) | 4.518 | 4.000 |
1.690 (2)–1.690 (8) | 4.457 | 3.947 | |||
MgSiF6·6H2O | 250196 | (Cherkasova et al., 2004) | 1.6888 (9)–1.7465 (10) | 4.194 | 3.714 |
MnSiF6·6H2O | 59274 | (Torii et al., 1997) | 1.690 (7) | 4.457 | 3.947 |
1.668 (7)–1.693 (7) | 4.575 | 4.051 | |||
(NH3OH)2SiF6·2H2O | 94567 | (Kristl et al., 2002) | 1.6793 (10)–1.6837 (10) | 4.570 | 4.046 |
(NH4)2SiF6 | 54724 | (Fábry et al., 2001) | 1.695 (1)–1.700 (1) | 4.368 | 3.867 |
(N2H5)2SiF6 | 776 | (Ouasri et al., 2019) | 1.6777 (4)–1.7101 (4) | 4.476 | 3.963 |
(N2H6)SiF6 | 35702 | (Cameron et al., 1983) | 1.671 (1)–1.683 (1) | 4.596 | 4.070 |
Na2SiF6 | 433134 | (Zhang et al., 2017) | 1.6755 (14)–1.6756 (14) | 4.635 | 4.104 |
1.6907 (16)–1.6916 (11) | 4.443 | 3.934 | |||
PbSiF6·2H2O | 39358 | (Golubev et al., 1991) | 1.645 (10)–1.707 (10) | 4.558 | 4.036 |
1.664 (10)–1.716 (10) | 4.411 | 3.906 | |||
Rb2SiF6 | 136303 | (Rienmüller et al., 2021) | 1.693 (3) | 4.421 | 3.915 |
[RuF(NH3)4(NO)]SiF6 | 703 | (Mikhailov et al., 2019) | 1.661 (1)–1.713 (2) | 4.556 | 4.035 |
[Ru2(H2O)2(NH4)8S2](SiF6)2 | 111446 | (Woods & Wilson, 2021) | 1.666 (2)–1.7065 (19) | 4.552 | 4.031 |
SiF4 | 48147 | (Mootz & Korte, 1984) | 1.5401 (6) | 4.455 | 3.945 |
SrSiF6·2H2O | 20552 | (Golovastikov & Belov, 1982) | 1.675 (5)–1.700 (5) | 4.502 | 3.987 |
[Tl2(NH3)6]SiF6·2NH3 | 144214 | (Rudel et al., 2021) | 1.687 (2)–1.6877 (15) | 4.488 | 3.974 |
Tl2SiF6 | 136300 | (Rienmüller et al., 2021) | 1.686 (6) | 4.505 | 3.989 |
Tl3F[SiF6] | 136302 | (Rienmüller et al., 2021) | 1.688 (6)–1.695 (6) | 4.439 | 3.931 |