Calcium hexa-kis(dihydrogen-phosphito)-stannate(IV), Ca[Sn(H2PO2)6], with some remarks on the so-called Ge2(H2PO2)6 structure type.

The title compound, Ca[Sn(H2PO2)6], was formed after a few days when tin(II) fluoride was allowed to react with phosphinic acid at ambient conditions. The structure consists of chains of Ca(2+) and Sn(4+) cations in octa-hedral sites with -3 symmetry bridged by bidentate hypophosphite anions. The chains are hexa-gonally close packed along [001]. The discovery of the compound and the successful structure refinement provides strong evidence that an isostructural compound, originally described as the mixed-valence compound, Ge2[H2PO2]6 [Weakley (1983 ▶). J. Chem. Soc. Pak. 5, 279-281], must be reformulated as Ca[Ge(H2PO2)6].

Related literature

For the reaction of SnF2 with H3PO2, see: Everest (1951 ▶). For the structures of Ge2(H2PO2)6, see: Weakley (1983 ▶), and Fe2(H2PO2)6, see: Kuratieva & Naumov (2006 ▶). For the so-called Ge2(H2PO2)6 structure type, see: Bergerhoff et al. (1999 ▶); Villars et al. (2010 ▶). For Ca—O bond lengths, see: Smith & Leider (1968 ▶) and for Sn—O bond lengths, see: Yamanaka et al. (2000 ▶). Bond-valence sums were calculated using Valist (Wills, 2010 ▶)

Experimental

Crystal data

Ca[Sn(H2PO2)6]

M = 548.69

Hexagonal,

a = 11.8619 (4) Å

c = 9.8668 (4) Å

V = 1202.31 (8) Å3

Z = 3

Mo Kα radiation

μ = 2.56 mm−1

T = 100 K

0.36 × 0.11 × 0.05 mm

Data collection

Bruker APEXII CCD diffractometer

Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T min = 0.459, T max = 0.887

18525 measured reflections

777 independent reflections

731 reflections with I > 2σ(I)

R int = 0.054

Refinement

R[F 2 > 2σ(F 2)] = 0.020

wR(F 2) = 0.058

S = 1.21

777 reflections

33 parameters

H-atom parameters constrained

Δρmax = 1.02 e Å−3

Δρmin = −0.42 e Å−3

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg, 2006 ▶) and Mercury (Macrae et al., 2008 ▶); software used to prepare material for publication: SHELXTL (Sheldrick, 2008 ▶).

Crystal structure: contains datablock(s) I, New_Global_Publ_Block. DOI: 10.1107/S1600536813018205/cq2005sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536813018205/cq2005Isup2.hkl

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

Ca[Sn(H2PO2)6]	Dx = 2.273 Mg m−3
Mr = 548.69	Mo Kα radiation, λ = 0.71073 Å
Hexagonal, R3	Cell parameters from 6570 reflections
Hall symbol: -R 3	θ = 2.9–30.0°
a = 11.8619 (4) Å	µ = 2.56 mm−1
c = 9.8668 (4) Å	T = 100 K
V = 1202.31 (8) Å3	Needle, colourless
Z = 3	0.36 × 0.11 × 0.05 mm
F(000) = 804

Bruker APEXII CCD diffractometer	777 independent reflections
Radiation source: fine-focus sealed tube	731 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.054
φ and ω scans	θmax = 30.0°, θmin = 3.4°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −16→16
Tmin = 0.459, Tmax = 0.887	k = −16→16
18525 measured reflections	l = −13→13

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.020	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.058	H-atom parameters constrained
S = 1.21	w = 1/[σ2(Fo2) + (0.0229P)2 + 3.9531P] where P = (Fo2 + 2Fc2)/3
777 reflections	(Δ/σ)max = 0.001
33 parameters	Δρmax = 1.02 e Å−3
0 restraints	Δρmin = −0.42 e Å−3

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.

	x	y	z	Uiso*/Ueq
Sn1	1.0000	1.0000	0.0000	0.01807 (11)
Ca1	1.0000	1.0000	0.5000	0.0192 (2)
P1	0.78540 (5)	0.97330 (6)	0.22095 (6)	0.02205 (14)
H1	0.7214	0.8488	0.1657	0.040 (6)*
H2	0.7073	1.0296	0.2122	0.040 (6)*
O1	0.89193 (16)	1.05182 (16)	0.11547 (15)	0.0244 (3)
O2	0.82943 (19)	0.9728 (2)	0.36084 (18)	0.0408 (5)

	U11	U22	U33	U12	U13	U23
Sn1	0.02121 (13)	0.02121 (13)	0.01179 (16)	0.01061 (7)	0.000	0.000
Ca1	0.0229 (3)	0.0229 (3)	0.0117 (4)	0.01146 (15)	0.000	0.000
P1	0.0205 (3)	0.0291 (3)	0.0184 (3)	0.0138 (2)	0.00185 (19)	0.0010 (2)
O1	0.0300 (8)	0.0253 (8)	0.0196 (7)	0.0150 (7)	0.0060 (6)	0.0019 (6)
O2	0.0325 (10)	0.0739 (15)	0.0187 (8)	0.0286 (10)	0.0021 (7)	0.0070 (8)

Sn1—O1i	2.0265 (15)	Ca1—O2ii	2.3302 (19)
Sn1—O1ii	2.0265 (15)	Ca1—O2viii	2.3302 (19)
Sn1—O1iii	2.0266 (16)	Ca1—O2iv	2.3302 (19)
Sn1—O1iv	2.0266 (16)	Ca1—O2	2.3303 (19)
Sn1—O1	2.0266 (15)	P1—O2	1.4768 (18)
Sn1—O1v	2.0266 (16)	P1—O1	1.5397 (16)
Ca1—O2vi	2.3302 (19)	P1—H1	1.3900
Ca1—O2vii	2.3302 (19)	P1—H2	1.3900
O1i—Sn1—O1ii	180.0	O2vii—Ca1—O2viii	88.81 (7)
O1i—Sn1—O1iii	91.49 (6)	O2ii—Ca1—O2viii	91.19 (7)
O1ii—Sn1—O1iii	88.51 (6)	O2vi—Ca1—O2iv	91.19 (7)
O1i—Sn1—O1iv	88.51 (6)	O2vii—Ca1—O2iv	91.19 (7)
O1ii—Sn1—O1iv	91.49 (6)	O2ii—Ca1—O2iv	88.81 (7)
O1iii—Sn1—O1iv	180.00 (11)	O2viii—Ca1—O2iv	180.0
O1i—Sn1—O1	88.52 (6)	O2vi—Ca1—O2	180.0
O1ii—Sn1—O1	91.48 (6)	O2vii—Ca1—O2	91.19 (7)
O1iii—Sn1—O1	88.52 (6)	O2ii—Ca1—O2	88.81 (7)
O1iv—Sn1—O1	91.48 (6)	O2viii—Ca1—O2	91.19 (7)
O1i—Sn1—O1v	91.48 (6)	O2iv—Ca1—O2	88.81 (7)
O1ii—Sn1—O1v	88.52 (6)	O2—P1—O1	116.70 (11)
O1iii—Sn1—O1v	91.48 (6)	O2—P1—H1	111.6
O1iv—Sn1—O1v	88.52 (6)	O1—P1—H1	103.0
O1—Sn1—O1v	180.0	O2—P1—H2	112.5
O2vi—Ca1—O2vii	88.81 (7)	O1—P1—H2	102.1
O2vi—Ca1—O2ii	91.19 (7)	H1—P1—H2	110.1
O2vii—Ca1—O2ii	180.0	P1—O1—Sn1	130.45 (10)
O2vi—Ca1—O2viii	88.81 (7)	P1—O2—Ca1	146.56 (12)

Table 1

Selected bond lengths (Å)

Sn1—O1	2.0266 (15)
Ca1—O2	2.3303 (19)
P1—O2	1.4768 (18)
P1—O1	1.5397 (16)