Structural studies of lanthanide ion complexes of pure gold, pure silver and mixed metal (gold–silver) dicyanides

Abstract

Crystal structures of four lanthanide complexes of La[Au(CN)2](3).3H2O, La[Ag(CN)2](3).3H2O, La[Ag(0.83)Au(0.17)(CN)2](3).3H2O, and La[Ag(0.39)Au(0.61)(CN)2](3).3H2O are reported. Studies reveal that all the structures reported are isostructural. All systems were found to be in the hexagonal crystal system, space group P6(3)/mcm. The metal-metal distance for the pure gold system is 3.332 (1) A versus 3.359(1) A for the pure silver system. The mixed-metal systems have shown no distinct differences in the location of the metal atoms, with the La[Ag(0.83)Au(0.17)(CN)2](3).3H2O complex having a metal-metal Ag-Au separation of 3.346(1) A, and 3.344(1) A for the La[Ag(0.39)Au(0.61)(CN)2](3).3H2O complex. The crystal structures of the pure and mixed La complexes have been solved to provide evidence of Ag-Au heterometallic interactions and as a basis for understanding the interesting optical properties of the systems.

Hydrothermal synthesis, structural, Raman, and luminescence studies of Am[M(CN)2]3·3H2O and Nd[M(CN)2]3·3H2O (M=Ag, Au): Bimetallic coordination polymers containing both trans-plutonium and transition metal elements

“…This structural type has also been reported for several additional tris(dicyanoargentate)lanthanide trihydrates or tris(dicyanoaurate)lanthanide trihydrates [38,[41][42]. Due to the structural similarities of the 1-4 compounds reported here, for brevity, only the structure of Am[Ag(CN) 2 ] 3 Á 3H 2 O (1) will be discussed in detail; some important comparisons with the other structures will be addressed.…”

“…Previous reports have outlined the syntheses of similar tris-(dicyanoargentate) lanthanide trihydrates or tris-(dicyanoaurate) lanthanide trihydrates either by slow evaporation [18,26,37] or by gel growth [38] methods. Our synthetic approach for compounds 1-4 was to use the hydrothermal technique, a method that has also been used recently in the preparation of other transition metal cyanides [39][40].…”

Origin of the colossal positive and negative thermal expansion in Ag3[Co(CN)6]: anab initiodensity functional theory study

“…Because there are no experimental data on this structure, it is impossible to judge the extent to which an additional dispersive Au...Au interaction is required to give a complete description of the energy surface, but the work of Pyykkö and co-workers [20,21,22] suggest that there should be significant metallophilic interactions as in Ag 3 [Co(CN) 6 ]. Furthermore, the calculated value of the a lattice parameter is much larger (of order 1.43Å) than the experimental value for the isostructural La[Au(CN) 2 ] 3 , where a = 6.664Å at 213 K [26]. This suggests that it is highly likely that the behaviour of Au 3 [Co(CN) 6 ] and analogues such as La[Au(CN) 2 ] 3 will show colossal positive and negative thermal expansion.…”

Tunable excited state energy transfer in [

“…We have recently reported on studies of heterobimetallic crystals of the form R½Ag x Au 1Àx ðCNÞ 2 3 [5,[13][14][15]. These crystals have been found to have energies that are tunable not only by site-selective excitation and changes in temperature, but also by changing the Ag/Au ratio.…”

“…The crystals form in a quasi-two-dimensional layered structure, with layers of trivalent rare earth ions coordinated with water molecules alternating with layers of linear MðCNÞ À 2 ions [13,16]. The metal-metal distance in these systems (either Au-Au, Ag-Ag, or Au-Ag) is between 3.332 and 3.359 Å and the bond length between the CN ligand and the rare earth ion ranges from 2.653 to 2.671 Å [13].…”