Reduction of structural dimensionality through incorporation of auxiliary ligands in lanthanide tetracyanoplatinates

摘要

The synthesis of a series of lanthanide tetracyanoplatinates containing the auxiliary ligands 1,10′-phenanthroline (phen) or 2,2′-bipyridine (bpy) have been carried out by reaction of Ln~(3+) nitrate salts with phen or bpy and potassium tetracyanoplatinate in solvent systems containing dimethylsulfoxide and dimethylformamide. The use of these solvents has lead to the isolation of [{Ln(DMSO)_2(C_(12)H_8N _2)(H_2O)_3}_2Pt(CN)_4](Pt(CN) _4)_2·2C_(12)H_8N _2·4H_2O (Ln = Eu (Eu-1), Tb (Tb-1), Yb(Yb-1)), [Ln(DMF)_3(C_(12)H_8N_2)(H _2O)2NO_3]Pt(CN)_4 (Ln = La (La-2), Eu (Eu-2), Tb (Tb-2)), and [Ln(DMF)_3(C_(10)H_8N _2)(H_2O)_2NO_3]Pt(CN)_4 (Ln = La (La-3), Sm (Sm-3), Eu (Eu-3), Tb (Tb-3)) in the form of single crystals. Single-crystal X-ray diffraction has been used to investigate their structural features. The use of DMSO versus DMF as the solvent results in markedly different structural features. Eu-1 contains [{Eu(DMSO)_2(C _(12)H_8N_2)(H_2O)_3} _2Pt(CN)_4]~(2+) complex cations where the two Eu~(3+) centers are linked by a trans-bridging Pt(CN)_4~(2-) anion to form a dimeric lanthanide complex cation. An additional uncoordinated Pt(CN)_4~(2-) anion balances charge. Eu-2 and Eu-3 consist of zero-dimensional salts with [Eu(DMF)_3(C _(12)H_8N_2)(H_2O)_2(NO _3)]~(2+) or [Eu(DMF)_3(C_(10)H _8N_2)(H_2O)_2(NO_3)] ~(2+) complex cations, respectively, and only non-coordinated Pt(CN)_4~(2-) anions. Photoluminescence measurements illustrate that the Eu~(3+) and Tb~(3+) compounds for all three structure types display enhanced emission due to intramolecular energy transfer from the coordinated cyclic amines.