Hexachloroplatinates of the Lanthanides: Syntheses and Thermal Decomposition of [M(NO 3 ) 2 (H 2 O) 6 ] 2 [PtCl 6 ]·2H 2 O (M = La, Pr) and [M(NO 3 )(H 2 O) 7 ][PtCl 6 ]·4H 2 O (M = Gd, Dy)

The reaction of the nitrates M(NO 3 ) 3 ·6H 2 O (M = La, Pr) and (H 3 O) 2 PtCl 6 led to yellow single crystals of [M(NO 3 ) 2 (H 2 O) 6 ] 2 [PtCl 6 ]·2H 2 O (M = La, Pr) (monoclinic, P 2 1 / c , Z = 2, La/Pr: a = 697.4(3)/695.5(1), b = 1654.5(1)/1652.5(2), c = 1317.7(6)/1318.5(3) pm, β = 93.97°(7)/93.93°(2), R all = 0.0169/0.0659) while the reaction of M(NO 3 ) 3 ·5H 2 O (M = Gd, Dy) and (H 3 O) 2 PtCl 6 yielded yellow single crystals of [M(NO 3 )(H 2 O) 7 ][PtCl 6 ]·4H 2 O (monoclinic, P 2 1 / n , Z = 4, Gd/Dy: a = 838.72(3)/838.40(2), b = 2131.98(6)/2139.50(7), c = 1142.63(3)/1143.10(3) pm, β = 95.670(4)/95.698(3), R all = 0.0475/0.0337). The crystal structures consist of octahedral [PtCl 6 ] 2− anions and complex [M(NO 3 ) 2 (H 2 O) 6 ] 2 + and [M(NO 3 )(H 2 O) 7 ] 2+ cations, respectively. The thermal decomposition of both types of compounds leads via various steps to elemental platinum and the oxide chlorides MOCl (M = La, Pr, Gd, Dy).