Synthesis, crystal structure and Raman spectrum of K2[(Pt2)(HPO4)4(H2O)2] containing (Pt2)6+ ions

Panagiotidis, K.; Glaum, R.

doi:10.1107/S1600536809005601

inorganic compounds

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ISSN: 2056-9890

Volume 65| Part 3| March 2009| Pages i18-i19

doi:10.1107/S1600536809005601

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Synthesis, crystal structure and Raman spectrum of K₂[(Pt₂)(HPO₄)₄(H₂O)₂] containing (Pt₂)⁶⁺ ions

Kosta Panagiotidis ^a and Robert Glaum ^a ^*

^aInstitut für Anorganische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Strasse 1, D-53121 Bonn, Germany
^*Correspondence e-mail: rglaum@uni-bonn.de

(Received 18 December 2008; accepted 17 February 2009; online 21 February 2009)

In the crystal structure of the acid platinum phosphate dipotassium di-μ-hydrogenphosphato-bis[aquaplatinum(III)](Pt—Pt), K₂[Pt₂(HPO₄)₄(H₂O)₂], the (Pt₂)⁶⁺ dumbbells within the paddle-wheel complex show Pt—Pt distances of 2.4944 (5) and 2.4892 (5) Å. The pottassium ions are seven-fold coordinated by hydrogenphosphate groups. In the crystal, O—H⋯O hydrogen bonds help to establish the packing. The Raman spectrum was recorded.

Related literature

The structure of the title isotypic sodium compound, Na₂[Pt₂(HPO₄)₄(H₂O)₂], was determined by Cotton et al. (1982a ). For platinum phosphates, see: Wellmann & Liebau (1981 ). For related compounds containing dinuclear platinum(III), see: Bancroft et al. (1984 ); Baranovskii & Schelokow (1978 ); Che et al. (1982 ); Cotton & Walton (1982b ); Dikareva et al. (1982 , 1987 ); Muraveiskaya et al. (1974 , 1976 ); Pley & Wickleder (2004a ,b , 2005 ); Stein et al. (1983 ); Woollins & Kelly (1985 ). For the ternary system Pd/P/O, see: Palkina et al. (1978 ); Panagiotidis et al. (2005 ). For hydrogen bonds, see: Steiner (2002 ). For the Raman spectra of In₃(PO₄)₂ and In₂O(PO₄), see: Thauern & Glaum (2004 ). For the synthesis, see: Brauer (1978 ).

Experimental

Crystal data

K₂[Pt₂(HPO₄)₄(H₂O)₂]
M_r = 888.32
Triclinic, $[P \overline 1]$
a = 7.8852 (2) Å
b = 7.9657 (2) Å
c = 13.7739 (4) Å
α = 82.358 (1)°
β = 81.509 (1)°
γ = 65.528 (1)°
V = 776.32 (4) Å³
Z = 2
Mo Kα radiation
μ = 19.05 mm⁻¹
T = 123 K
0.24 × 0.14 × 0.08 mm

Data collection

Nonius Kappa CCD diffractometer
Absorption correction: multi-scan (Blessing, 1995 ) T_min = 0.060, T_max = 0.224
18915 measured reflections
5589 independent reflections
4077 reflections with I > 2σ(I)
R_int = 0.064

Refinement

R[F² > 2σ(F²)] = 0.033
wR(F²) = 0.086
S = 0.98
5589 reflections
259 parameters
10 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 3.46 e Å⁻³
Δρ_min = −2.87 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1A⋯O31ⁱ	0.83 (6)	1.73 (6)	2.559 (7)	173 (8)
O1—H1B⋯O21ⁱⁱ	0.84 (6)	2.09 (4)	2.860 (7)	153 (8)
O14—H14⋯O31ⁱⁱⁱ	0.83 (2)	1.82 (5)	2.548 (7)	146 (9)
O24—H24⋯O11^iv	0.84 (7)	1.73 (7)	2.562 (7)	177 (9)
O34—H34⋯O41^v	0.83 (6)	1.74 (3)	2.546 (6)	162 (9)
O10—H10A⋯O41^vi	0.86 (2)	1.94 (4)	2.713 (7)	148 (7)
O10—H10B⋯O11^vii	0.86 (2)	1.86 (2)	2.694 (6)	164 (6)
O42—H42⋯O21^viii	0.84 (7)	2.27 (9)	2.475 (7)	94 (6)
Symmetry codes: (i) -x, -y+1, -z+1; (ii) -x+2, -y, -z+1; (iii) -x, -y, -z+1; (iv) -x+2, -y-1, -z+1; (v) -x-1, -y+2, -z; (vi) -x, -y+2, -z; (vii) -x+1, -y, -z+1; (viii) -x+1, -y+1, -z.

Data collection: COLLECT (Hooft, 2004 ); cell refinement: SCALEPACK (Otwinowski & Minor, 1997 ); data reduction: DENZO (Otwinowski & Minor 1997) and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ATOMS (Dowty, 2006 ); software used to prepare material for publication: WinGX (Farrugia, 1999 ).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809005601/er2058sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809005601/er2058Isup2.hkl

checkCIF report

Comment top

Information on phosphates of noble metals like platinum and palladium is scarcely found in literature. During our recent investigation of the ternary system Pd/P/O we obtained the diphosphate Pd^II₂P₂O₇ (Panagiotidis et al., 2005) in addition to the already known Pd(PO₃)₂ (Palkina et al., 1978). In this context we were also interested in the crystal chemistry of platinum phosphates. Up to now, Pt^IVP₂O₇ (Wellmann & Liebau, 1981) is the only structurally characterized anhydrous phosphate of platinum. Since reactions starting from "PtO×3H₂O" and P₄O₁₀ did not yield products suitable for closer investigation we tried an alternative synthetic approach by reacting K₂PtCl₄ with conc. H₃PO₄(see Experimental). This led to the formation of orange crystals of K₂[(Pt₂)(HPO₄)₄(H₂O)₂]. The acid phosphate is isotypic to the sodium compound (Cotton et al., 1982a). In contrast to the structure of Na₂[(Pt₂)(HPO₄)₄(H₂O)₂] no disordered oxygen atoms are observed in the potassium compound. Distances d(Pt—Pt) for both structures are identical. The conventional residual as well as the standard deviations of the interatomic distances are slightly smaller for the refinement of K₂[(Pt₂)(HPO₄)₄(H₂O)₂]. The (Pt₂)⁶⁺ binuclear complex was first observed in the crystal structure of K₂[(Pt₂(SO₄)₄(H₂O)₂] (Muraveiskaya et al., 1974; Muraveiskaya et al., 1976). By reaction of elemental platinum with concentrated sulfuric acid various platinum(III) sulfates were recently synthesized and structurally characterized (Pley & Wickleder, 2004a,b; Pley & Wickleder, 2005).

In K₂[(Pt₂)(HPO₄)₄(H₂O)₂] two crystallographically equivalent platinum atoms are connected to form (Pt₂)⁶⁺ dinuclear complexes with surrounding (HPO₄)^2- groups (Fig. 1). The ligating oxygen atoms of the (HPO₄)^2- ions are arranged in a square-planar coordination around each platinum atom. Distances d(Pt—O) range from 1.978 Å to 2.030 Å. Angles 〈(O,Pt,O) are deviating only slightly from 90° and 180°, respectively. Due to their different crystal chemical environment, the oxygen atoms of the hydrogenphosphate anions show significantly different bond lenghts d(P—O). Oxygen atoms attached to platinum (coordination number of oxygen c.n.(O) = 2 (P, Pt)) show distances d(P—O) = 1.55 Å. Distances d(P—O) for those oxygen atoms which are coordinated to K⁺ ions (c.n.(O) = 2 (P, K)) range from 1.489 Å to 1.507 Å. Furthermore, for oxygen atoms which are attached to a hydrogen atom within the (HPO₄)^2- unit (c.n.(O) = 2, (P, H)), distances d(P—OH) around 1.565 Å are observed. The axial ligand positions of the Pt₂ dumbbells are occupied by water molecules (Fig. 1 & 2). Distances d(Pt—O) = 2.135 Å observed for the water ligands are significantly longer than those within the [Pt₂O₈] entity. The hydrogen atoms of [HPO₄] tetrahedra (H14, H24, H34, H42; numbering according to the oxygen atoms that cary the hydrogen) and the water molecules (H1A, H1B, H10A, H10B) are involved in hydrogen bonding with oxygen atoms of adjacent [(Pt₂)(HPO₄)(H₂O)₂]^2- units. Interatomic distances d(OH···OP) range from 1.73 Å to 2.27 Å. They are in good accordance with those observed for strong hydrogen bonds (Steiner, 2002).

As found for various other compounds containing the (Pt₂)⁶⁺ dinuclear complex, the angle 〈(Pt,Pt,O) between the dumbbell and the axial oxygen atoms deviates only slightly from 180° (Cotton et al., 1982b; Pley & Wickleder et al., 2005). [HPO₄] tetrahedra in [(Pt₂)(HPO₄)(H₂O)₂]^2- show no significant angular distortion. Charge compensation of the anionic [Pt^III₂(HPO₄)₄(H₂O)₂]^2- unit is achieved by two crystallographically independent K⁺ ions, which are surrounded by oxygen atoms of phosphate groups.

In addition to its structure refinement, we were able to record the Raman spectrum of the paddle-wheel complex [Pt^III₂(HPO₄)₄(H₂O)₂]^2- (Fig. 3). An unequivocal assignment of the observed signals is yet impossible. Comparison of the Raman spectrum to those of the In₂⁴⁺ containing indium phosphates In₃(PO₄)₂ and In₂O(PO₄) (Thauern & Glaum, 2004) suggests the Pt—Pt valence vibration to be at ν = 222 cm^-1. In comparison to ν(Pt—Pt) in complexes [(Pt^III₂)L₄L'₂]^n- (Stein et al., 1983) assignment of ν = 83 cm^-1 to the Pt—Pt vibration appears to be unreasonable. This is the more so, since d (Pt—Pt) = 2.51 Å observed for K₂[(Pt₂)(HPO₄)₄(H₂O)₂] is close to the lower limit of 2.47 Å < d (Pt—Pt) < 2.695 Å found for a series of dinuclear platinum(III) complexes (Che et al., 1982, Stein et al., 1983, Muraveiskaya et al., 1974).

Related literature top

The structure of the title isotypic sodium compound, Na₂[Pt₂(HPO₄)₄(H₂O)₂], was determined by Cotton et al. (1982a). For platinum phosphates, see: Wellmann & Liebau (1981). For related compounds containing dinuclear platinum(III), see: Bancroft et al. (1984); Baranovskii & Schelokow (1978); Che et al. (1982); Cotton & Walton (1982b); Dikareva et al. (1982, 1987); Muraveiskaya et al. (1974, 1976); Pley & Wickleder (2004a,b, 2005); Stein et al. (1983); Woollins & Kelly (1985). For the ternary system Pd/P/O, see: Palkina et al. (1978); Panagiotidis et al. (2005); For hydrogen bonds, see: Steiner (2002). For the Raman spectra of In₃(PO₄)₂ and In₂O(PO₄), see: Thauern & Glaum (2004). For the synthesis, see: Brauer (1978).

Experimental top

Aiming at the crystallization of "Pt₂P₂O₇" a reaction starting from 150.0 mg K₂Pt^IICl₄, which were dissolved in water and mixed with 5.0 ml conc. H₃PO₄, was performed. After the obtained red solution was kept in a desiccator over P₂O₅ for two weeks, plate-like, orange crystals of K₂[(Pt₂)(HPO₄)₄(H₂O)₂] with edge-lengths up to 0.3 mm were deposited besides microcrystalline platinum (eq. 1). The synthesis of K₂[Pt^IICl₄] was performed according to the procedure given by Brauer (1978).

3 K₂[Pt^IICl₄] + 4 H₃PO₄ + 2 H₂O → K₂[(Pt^III₂)(HPO₄)₄(H₂O)₂] + Pt_s + 8H⁺ + 12 C l^- + 4 K⁺ (eq. 1)

Computing details top

Data collection: COLLECT (Hooft, 2004); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO (Otwinowski & Minor 1997) and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ATOMS (Dowty, 2006); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top

	Fig. 1. Pa ddle-wheel complex [(Pt^III₂)(HPO₄)₄(H₂O)₂] with anisotropic displacement parameters given at the 50% level (Progr. ATOMS v.6.2).
	Fig. 2. Projection of the crystal strucure of K₂[(Pt₂)(HPO₄)₄(H₂O)₂] along [110]. [PO₄] tetrahedra (yellow), Pt₂⁶⁺ (red), K⁺ (violet), H+ (blue), O^2- (white) (Progr. ATOMS v.6.2).
	Fig. 3. Raman spectrum of K₂[(Pt₂)(HPO₄)₄(H₂O)₂].

dipotassium di-µ-hydrogenphosphato-bis[aquaplatinum(III)](Pt—Pt) top

Crystal data top

K₂[Pt₂(HPO₄)₄(H₂O)₂]	Z = 2
M_r = 888.32	F(000) = 812
Triclinic, P1	The lattice parameters of K₂[Pt₂(HPO₄)₄(H₂O)₂] were determined from single crystal diffraction data.
Hall symbol: -P 1	D_x = 3.800 Mg m⁻³
a = 7.8852 (2) Å	Mo Kα radiation, λ = 0.71073 Å
b = 7.9657 (2) Å	Cell parameters from 5589 reflections
c = 13.7739 (4) Å	θ = 1.5–32.5°
α = 82.358 (1)°	µ = 19.05 mm⁻¹
β = 81.509 (1)°	T = 123 K
γ = 65.528 (1)°	Plate, orange
V = 776.32 (4) Å³	0.24 × 0.14 × 0.08 mm

Data collection top

Nonius Kappa CCD diffractometer	5589 independent reflections
Radiation source: MoKα	4077 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.064
Detector resolution: 9 pixels mm^-1	θ_max = 32.5°, θ_min = 1.5°
CCD rotation images scans	h = −11→11
Absorption correction: multi-scan (Blessing, 1995)	k = −12→12
T_min = 0.060, T_max = 0.224	l = −19→20
18915 measured reflections

Refinement top

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)] = 0.033	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.086	H atoms treated by a mixture of independent and constrained refinement
S = 0.98	w = 1/[σ²(F_o²) + (0.0423P)²] where P = (F_o² + 2F_c²)/3
5589 reflections	(Δ/σ)_max = 0.001
259 parameters	Δρ_max = 3.46 e Å⁻³
10 restraints	Δρ_min = −2.87 e Å⁻³
0 constraints

Crystal data top

K₂[Pt₂(HPO₄)₄(H₂O)₂]	γ = 65.528 (1)°
M_r = 888.32	V = 776.32 (4) Å³
Triclinic, P1	Z = 2
a = 7.8852 (2) Å	Mo Kα radiation
b = 7.9657 (2) Å	µ = 19.05 mm⁻¹
c = 13.7739 (4) Å	T = 123 K
α = 82.358 (1)°	0.24 × 0.14 × 0.08 mm
β = 81.509 (1)°

Data collection top

Nonius Kappa CCD diffractometer	5589 independent reflections
Absorption correction: multi-scan (Blessing, 1995)	4077 reflections with I > 2σ(I)
T_min = 0.060, T_max = 0.224	R_int = 0.064
18915 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.033	10 restraints
wR(F²) = 0.086	H atoms treated by a mixture of independent and constrained refinement
S = 0.98	Δρ_max = 3.46 e Å⁻³
5589 reflections	Δρ_min = −2.87 e Å⁻³
259 parameters

Special details top

Geometry. All e.s.d.'s 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 and 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	U_iso*/U_eq
K1	0.1242 (4)	−0.3657 (4)	0.6326 (2)	0.0790 (9)
K2	0.3845 (3)	−0.1884 (3)	0.90856 (15)	0.0472 (5)
O1	0.6393 (7)	0.2464 (8)	0.6286 (4)	0.0289 (11)
H1A	0.566 (8)	0.299 (10)	0.676 (4)	0.043*
H1B	0.734 (6)	0.175 (9)	0.656 (5)	0.043*
O12	0.6784 (7)	−0.1304 (6)	0.6372 (3)	0.0238 (10)
O14	0.4660 (7)	−0.2761 (7)	0.7170 (4)	0.0305 (11)
H14	0.486 (13)	−0.387 (4)	0.717 (6)	0.046*
O11	0.8028 (7)	−0.4742 (7)	0.6678 (3)	0.0256 (10)
O13	0.5849 (7)	−0.3216 (6)	0.5370 (3)	0.0245 (10)
O22	0.7832 (6)	0.0412 (7)	0.4628 (4)	0.0247 (10)
O24	0.9754 (7)	−0.3003 (7)	0.4569 (3)	0.0276 (11)
H24	1.045 (10)	−0.372 (10)	0.415 (5)	0.041*
O21	0.9903 (7)	−0.0893 (7)	0.3117 (4)	0.0298 (11)
O23	0.6936 (6)	−0.1446 (7)	0.3608 (3)	0.0267 (10)
O10	0.2526 (7)	0.5993 (7)	0.1437 (3)	0.0249 (10)
H10A	0.207 (11)	0.719 (3)	0.141 (5)	0.037*
H10B	0.226 (11)	0.582 (9)	0.2058 (19)	0.037*
O32	−0.1067 (6)	0.5907 (6)	0.1622 (3)	0.0212 (9)
O33	−0.3103 (6)	0.5226 (6)	0.0567 (3)	0.0199 (9)
O34	−0.4078 (7)	0.8408 (7)	0.1168 (4)	0.0286 (11)
H34	−0.520 (4)	0.896 (11)	0.107 (6)	0.043*
O31	−0.4038 (6)	0.5674 (7)	0.2362 (3)	0.0231 (10)
O44	−0.0110 (6)	0.8018 (7)	0.0001 (3)	0.0236 (10)
O41	−0.2456 (6)	1.0558 (6)	−0.0996 (3)	0.0233 (10)
O43	−0.2059 (6)	0.7307 (6)	−0.1068 (3)	0.0210 (9)
O42	0.0530 (7)	0.8330 (7)	−0.1816 (4)	0.0310 (12)
H42	0.050 (13)	0.930 (7)	−0.162 (6)	0.047*
P1	0.6381 (2)	−0.3051 (2)	0.63814 (12)	0.0220 (3)
P2	0.8592 (2)	−0.1187 (2)	0.39488 (12)	0.0215 (3)
P3	−0.3082 (2)	0.6280 (2)	0.14389 (12)	0.0180 (3)
P4	−0.1056 (2)	0.8585 (2)	−0.09741 (12)	0.0187 (3)
Pt1	0.54549 (3)	0.09217 (3)	0.549475 (17)	0.01966 (7)
Pt2	0.09528 (3)	0.53533 (3)	0.052197 (16)	0.01543 (6)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
K1	0.101 (2)	0.087 (2)	0.0691 (17)	−0.0526 (18)	−0.0488 (16)	0.0208 (15)
K2	0.0525 (12)	0.0601 (13)	0.0406 (10)	−0.0346 (11)	0.0048 (9)	−0.0133 (9)
O1	0.030 (3)	0.030 (3)	0.029 (3)	−0.013 (2)	0.000 (2)	−0.010 (2)
O12	0.030 (2)	0.020 (2)	0.021 (2)	−0.011 (2)	−0.0040 (19)	0.0035 (18)
O14	0.032 (3)	0.028 (3)	0.028 (3)	−0.014 (2)	0.007 (2)	0.001 (2)
O11	0.028 (2)	0.021 (2)	0.019 (2)	−0.003 (2)	−0.0023 (19)	0.0031 (18)
O13	0.029 (2)	0.019 (2)	0.021 (2)	−0.006 (2)	−0.0018 (19)	0.0019 (18)
O22	0.019 (2)	0.023 (2)	0.030 (3)	−0.007 (2)	0.0021 (19)	−0.005 (2)
O24	0.029 (3)	0.026 (3)	0.019 (2)	−0.005 (2)	0.0028 (19)	0.0021 (19)
O21	0.022 (2)	0.031 (3)	0.029 (3)	−0.008 (2)	0.0055 (19)	0.007 (2)
O23	0.021 (2)	0.028 (3)	0.025 (2)	−0.005 (2)	0.0031 (19)	−0.006 (2)
O10	0.028 (2)	0.032 (3)	0.020 (2)	−0.018 (2)	−0.0068 (19)	0.0045 (19)
O32	0.018 (2)	0.023 (2)	0.020 (2)	−0.0061 (19)	−0.0014 (17)	−0.0005 (18)
O33	0.018 (2)	0.025 (2)	0.016 (2)	−0.0101 (19)	0.0043 (16)	−0.0019 (17)
O34	0.020 (2)	0.025 (3)	0.038 (3)	−0.006 (2)	−0.003 (2)	−0.001 (2)
O31	0.024 (2)	0.026 (3)	0.019 (2)	−0.013 (2)	0.0055 (18)	−0.0032 (18)
O44	0.021 (2)	0.023 (2)	0.028 (2)	−0.011 (2)	−0.0080 (18)	0.0054 (19)
O41	0.021 (2)	0.017 (2)	0.031 (3)	−0.0073 (19)	−0.0051 (19)	0.0016 (19)
O43	0.022 (2)	0.020 (2)	0.019 (2)	−0.0077 (19)	−0.0011 (17)	0.0025 (17)
O42	0.025 (2)	0.025 (3)	0.034 (3)	−0.007 (2)	0.008 (2)	0.004 (2)
P1	0.0237 (8)	0.0200 (8)	0.0183 (8)	−0.0061 (7)	−0.0002 (6)	0.0009 (6)
P2	0.0194 (8)	0.0218 (9)	0.0189 (8)	−0.0066 (7)	0.0020 (6)	0.0024 (6)
P3	0.0150 (7)	0.0204 (8)	0.0172 (7)	−0.0071 (6)	0.0016 (6)	−0.0005 (6)
P4	0.0167 (7)	0.0176 (8)	0.0190 (7)	−0.0057 (6)	−0.0011 (6)	0.0033 (6)
Pt1	0.02042 (12)	0.01997 (13)	0.01736 (12)	−0.00806 (10)	0.00056 (9)	−0.00042 (9)
Pt2	0.01457 (11)	0.01729 (12)	0.01430 (11)	−0.00707 (9)	−0.00109 (8)	0.00101 (8)

Geometric parameters (Å, º) top

K1—O24ⁱ	2.739 (6)	O24—P2	1.570 (5)
K1—O31ⁱⁱ	2.860 (5)	O21—P2	1.489 (5)
K1—O11ⁱ	2.957 (6)	O23—P2	1.549 (5)
K1—O42ⁱⁱⁱ	3.047 (6)	O23—Pt1^iv	2.014 (5)
K1—O22^iv	3.053 (5)	O10—Pt2	2.132 (5)
K1—O32ⁱⁱ	3.156 (5)	O32—P3	1.544 (5)
K1—O12ⁱ	3.222 (6)	O32—Pt2	1.978 (4)
K2—O14	2.735 (6)	O33—P3	1.561 (5)
K2—O34^v	2.822 (6)	O33—Pt2^vii	2.030 (4)
K2—O41^v	2.858 (5)	O34—P3	1.564 (5)
K2—O33ⁱⁱ	2.920 (5)	O31—P3	1.507 (4)
K2—O42ⁱⁱⁱ	2.990 (6)	O44—P4	1.555 (5)
K2—O43^vi	3.000 (5)	O44—Pt2	2.005 (5)
K2—O44ⁱⁱⁱ	3.215 (5)	O41—P4	1.500 (5)
O1—Pt1	2.143 (5)	O43—P4	1.553 (5)
O12—P1	1.549 (5)	O43—Pt2^vii	2.014 (4)
O12—Pt1	1.992 (4)	O42—P4	1.541 (5)
O14—P1	1.564 (5)	Pt1—O13^iv	2.010 (4)
O11—P1	1.493 (5)	Pt1—O23^iv	2.014 (5)
O13—P1	1.549 (5)	Pt1—Pt1^iv	2.4944 (5)
O13—Pt1^iv	2.010 (4)	Pt2—O43^vii	2.014 (4)
O22—P2	1.541 (5)	Pt2—O33^vii	2.030 (4)
O22—Pt1	1.985 (4)	Pt2—Pt2^vii	2.4892 (5)

O11—P1—O12	110.2 (3)	O22—Pt1—O23^iv	179.02 (19)
O11—P1—O13	110.9 (3)	O12—Pt1—O23^iv	90.37 (19)
O12—P1—O13	111.5 (3)	O13^iv—Pt1—O23^iv	89.97 (19)
O11—P1—O14	110.2 (3)	O22—Pt1—O1	85.5 (2)
O12—P1—O14	104.8 (3)	O12—Pt1—O1	88.0 (2)
O13—P1—O14	109.0 (3)	O13^iv—Pt1—O1	90.0 (2)
O21—P2—O22	111.1 (3)	O23^iv—Pt1—O1	93.6 (2)
O21—P2—O23	113.2 (3)	O22—Pt1—Pt1^iv	90.98 (14)
O22—P2—O23	109.6 (3)	O12—Pt1—Pt1^iv	91.86 (14)
O21—P2—O24	106.9 (3)	O13^iv—Pt1—Pt1^iv	90.05 (14)
O22—P2—O24	107.7 (3)	O23^iv—Pt1—Pt1^iv	89.91 (15)
O23—P2—O24	108.1 (3)	O1—Pt1—Pt1^iv	176.49 (14)
O31—P3—O32	108.9 (3)	O32—Pt2—O44	90.05 (19)
O31—P3—O33	109.3 (3)	O32—Pt2—O43^vii	89.88 (18)
O32—P3—O33	111.8 (3)	O44—Pt2—O43^vii	178.49 (18)
O31—P3—O34	111.6 (3)	O32—Pt2—O33^vii	177.57 (17)
O32—P3—O34	106.3 (3)	O44—Pt2—O33^vii	90.65 (19)
O33—P3—O34	108.9 (3)	O43^vii—Pt2—O33^vii	89.36 (18)
O41—P4—O42	110.7 (3)	O32—Pt2—O10	87.17 (19)
O41—P4—O43	109.3 (3)	O44—Pt2—O10	89.05 (19)
O42—P4—O43	110.0 (3)	O43^vii—Pt2—O10	89.45 (19)
O41—P4—O44	110.6 (3)	O33^vii—Pt2—O10	90.51 (18)
O42—P4—O44	106.4 (3)	O32—Pt2—Pt2^vii	91.55 (13)
O43—P4—O44	109.7 (2)	O44—Pt2—Pt2^vii	90.52 (13)
O22—Pt1—O12	89.21 (19)	O43^vii—Pt2—Pt2^vii	90.99 (13)
O22—Pt1—O13^iv	90.42 (19)	O33^vii—Pt2—Pt2^vii	90.77 (13)
O12—Pt1—O13^iv	178.06 (19)	O10—Pt2—Pt2^vii	178.65 (14)

Symmetry codes: (i) x−1, y, z; (ii) −x, −y, −z+1; (iii) x, y−1, z+1; (iv) −x+1, −y, −z+1; (v) −x, −y+1, −z+1; (vi) x+1, y−1, 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—H1A···O31^v	0.83 (6)	1.73 (6)	2.559 (7)	173 (8)
O1—H1B···O21^viii	0.84 (6)	2.09 (4)	2.860 (7)	153 (8)
O14—H14···O31ⁱⁱ	0.83 (2)	1.82 (5)	2.548 (7)	146 (9)
O24—H24···O11^ix	0.84 (7)	1.73 (7)	2.562 (7)	177 (9)
O34—H34···O41^x	0.83 (6)	1.74 (3)	2.546 (6)	162 (9)
O10—H10A···O41^xi	0.86 (2)	1.94 (4)	2.713 (7)	148 (7)
O10—H10B···O11^iv	0.86 (2)	1.86 (2)	2.694 (6)	164 (6)
O42—H42···O21^xii	0.84 (7)	2.27 (9)	2.475 (7)	94 (6)

Symmetry codes: (ii) −x, −y, −z+1; (iv) −x+1, −y, −z+1; (v) −x, −y+1, −z+1; (viii) −x+2, −y, −z+1; (ix) −x+2, −y−1, −z+1; (x) −x−1, −y+2, −z; (xi) −x, −y+2, −z; (xii) −x+1, −y+1, −z.

Experimental details

Crystal data
Chemical formula	K₂[Pt₂(HPO₄)₄(H₂O)₂]
M_r	888.32
Crystal system, space group	Triclinic, P1
Temperature (K)	123
a, b, c (Å)	7.8852 (2), 7.9657 (2), 13.7739 (4)
α, β, γ (°)	82.358 (1), 81.509 (1), 65.528 (1)
V (Å³)	776.32 (4)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	19.05
Crystal size (mm)	0.24 × 0.14 × 0.08

Data collection
Diffractometer	Nonius Kappa CCD diffractometer
Absorption correction	Multi-scan (Blessing, 1995)
T_min, T_max	0.060, 0.224
No. of measured, independent and observed [I > 2σ(I)] reflections	18915, 5589, 4077
R_int	0.064
(sin θ/λ)_max (Å⁻¹)	0.756

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.033, 0.086, 0.98
No. of reflections	5589
No. of parameters	259
No. of restraints	10
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	3.46, −2.87

Computer programs: COLLECT (Hooft, 2004), SCALEPACK (Otwinowski & Minor, 1997), DENZO (Otwinowski & Minor 1997) and SCALEPACK, SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ATOMS (Dowty, 2006), WinGX (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1A···O31ⁱ	0.83 (6)	1.73 (6)	2.559 (7)	173 (8)
O1—H1B···O21ⁱⁱ	0.84 (6)	2.09 (4)	2.860 (7)	153 (8)
O14—H14···O31ⁱⁱⁱ	0.83 (2)	1.82 (5)	2.548 (7)	146 (9)
O24—H24···O11^iv	0.84 (7)	1.73 (7)	2.562 (7)	177 (9)
O34—H34···O41^v	0.83 (6)	1.74 (3)	2.546 (6)	162 (9)
O10—H10A···O41^vi	0.86 (2)	1.94 (4)	2.713 (7)	148 (7)
O10—H10B···O11^vii	0.86 (2)	1.86 (2)	2.694 (6)	164 (6)
O42—H42···O21^viii	0.84 (7)	2.27 (9)	2.475 (7)	94 (6)

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

Acknowledgements

We thank G. Schnakenburg (University of Bonn) for the single-crystal data collection and D. Ernsthäuser (University of Bonn) for the measurement of the Raman spectrum. This work was financially supported by Deutsche Forschungsgemeinschaft (DFG). A noble metal donation by UMICORE AG (Hanau-Wolfgang, Germany) is gratefully acknowledged.

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