Crystal structure of bis(1,10-phenanthrolinium) hexabromoplatinate(IV), [C12H9N2]2[PtBr6

Abstract

C24H18Br6N4Pt, triclinic, P1 (no. 2), a = 7.604(1) A, b = 8.100(1) A, c = 11.110(2) A, + = 84.351(3)°, ) = 81.358(3)°, & = 88.421(3)°, V = 673.1 A, Z = 1, Rgt(F) = 0.054, wRref(F) = 0.171, T = 223 K. Source of material A suspension of K2PtCl6 (0.261 g, 0.537 mmol), 1,10-phenanthroline (0.100.g, 0.555.mmol) and NaBr (0.884.g, 8.591.mmol) in H2O (10 ml) was refluxed for 4 h at 100 °C. After cooling, the formed precipitate was separated by filtration, washedwithwater and dried under vacuum, to give an orange powder (0.277 g). Crystals suitable for X-ray structure analysis were obtained by slow evaporation from a CH3CN solution. Experimental details H atoms were positioned geometrically and allowed to ride on their respective parent atoms [d(C—H) = 0.94 A, d(N—H) = 0.87.A and Uiso(H) = 1.2Ueq(C,N)]. Some large residue electron densities were found close to Pt and Br atoms. Owing to the poor quality of the crystal the H atoms on C and N atoms could not be located from Fourier difference maps. However, one of the N atoms of the 1,10-phenanthroline molecule had to be protonated for charge balancing. For the refinement of the structure H atoms were added geometrically on bothN atomswith an occupancy ratio of 0.5/0.5, because it was not distinct which N atom was protonated. The large R-values are connected with the poor quality of the crystal. Discussion The title compound with a crystallization water molecule, (C12H9N2)2[PtBr6].·.H2O, was previously prepared by the reaction of H2[PtBr6].·.6H2O with 1,10-phenanthroline and HBr, and its thermal decomposition was studied by means of derivatography and differential scanning calorimetry [1]. The crystal structure of the title compound consists of twomonoprotonated 1,10-phenanthroline cations and an anionic Pt(IV) complex. The asymmetric unit contains one half of the formula unit; a center of inversion is located at the Pt atom in the special position (1⁄2,0,1⁄2). In the complex, the Pt(IV) ion is sixcoordinated in an almost perfect octahedral environment by six Br atoms: the Pt—Br bond lengths are nearly equivalent with the range of 2.467(2) 2.477(2) A, and the cis ∠Br−Pt−Br bond angles lie in the range of 88.22(5) 91.78(5)°. These values are similar to those found in the complexes K2[PtBr6] [2], [Rh(NH3)5Cl][PtBr6] [3] and (C21H19N2)2[PtBr6] [4]. The compound displays numerous intermolecular --interactions between six-membered rings of the phenanthrolinium cation. The distance between Cg1 (the centroid of six-membered ring N2C11) and Cg1 (symmetry code i: 1−x,1−y,−z) is 3.53(1) A, and the dihedral angle between the ring planes is 0°. Moreover, there are interand intramolecular N−H···Br and N−H···N hydrogen bonds with d(N···Br) = 3.39(1) A and d(N···N) = 2.72(2) A. Z. Kristallogr. NCS 225 (2010) 37-38 / DOI 10.1524/ncrs.2010.0014 37 © by Oldenbourg Wissenschaftsverlag, Munchen Crystal: orange block, size 0.05 × 0.07 × 0.20 mm Wavelength: Mo K+ radiation (0.71073 A) .: 141.38 cm−1 Diffractometer, scan mode: Bruker SMART 1000 CCD, #/% 2,max: 56.6° N(hkl)measured, N(hkl)unique: 4959, 3232 Criterion for Iobs, N(hkl)gt: Iobs > 2 ((Iobs), 2478 N(param)refined: 160 Programs: SHELXS-97 [5], SHELXL-97 [6], ORTEP-III [7], PLATON [8] Table 1. Data collection and handling. H(1A) 2i 0.50 0.1757 0.1994 0.2352 0.038 H(2A) 2i 0.50 0.3002 0.1676 0.0861 0.048 H(1) 2i −0.0024 0.2032 0.4154 0.038 H(2) 2i −0.1608 0.4472 0.4565 0.043 H(3) 2i −0.1040 0.6811 0.3265 0.044 H(5) 2i 0.0404 0.8226 0.1204 0.048 H(6) 2i 0.2152 0.7936 −0.0638 0.044 H(8) 2i 0.3985 0.6084 −0.2127 0.051 H(9) 2i 0.5004 0.3410 −0.2505 0.059 H(10) 2i 0.4528 0.1315 −0.0943 0.054 Table 2. Atomic coordinates and displacement parameters (in A). Atom Site Occ. x y z Uiso