Coordination chemistry of rare-earth elements has been dominated by the+3 oxidation state.Complexes with higher-valence lanthanide ions are synthetically challenging but are of fundamental research interest and signif...Coordination chemistry of rare-earth elements has been dominated by the+3 oxidation state.Complexes with higher-valence lanthanide ions are synthetically challenging but are of fundamental research interest and significance as advanced molecular materials.Herein,four tetravalent terbium complexes(2-5)of the common formula[Tb(OSiPh3)4L](L=ethylene glycol dimethyl ether(DME),2,2’-bipyridine(bpy),2,2’-bipyrimidine(bpym),and 1,10-phenanthroline(phen))are reported.Crystallographic analyses reveal in each of these complexes a hexacoordinate Tb(IV)ion situated in a distorted octahedral coordination environment formed by four triphenylsi-loxido ligands and a bidentate chelating ligand.The use of chelating ligands enhances the stability of the resulting complexes over their THF solvate precursor.More significantly,the aromatic N-chelating ligands have been found to tune effectively the electronic structures of the complexes,as evidenced by the sizable potential shifts observed for the quasi-reversible redox Tb(IV/III)process and by the changes in their absorption spectra.The experimental findings are augmented with quantum theoretical calculations in which the ligandπ-donation to the 5d orbitals of the Tb(IV)center is found to be primarily responsible for stability enhancement and the corresponding changes of physical properties observed.Magnetic measurements and results from electron paramagnetic resonance studies produced small absolute values of zero-field splittings of these complexes,ranging from 0.1071(22)to 1.1484(112)cm-1 and comparable to the values reported for analogous Tb(IV)complexes.展开更多
基金supported by the National Natural Science Foundation of China(92261203,22101116,22033005 and 21971106)Key Laboratory of Rare Earth Chemistry of Guangdong Higher Education Institutes(2022KSYS006)+2 种基金the Stable Support Plan Program of Shenzhen Natural Science Fund(20200925161141006),Shenzhen Fundamental Research Program(JCYJ20220530115001002)Postdoctoral Scientific Research Fund for staying at(coming to)Shenzhen(K21217520)The calculations were performed with SUSTech supercomputer and were supported by Guangdong Provincial Key Laboratory of Catalysis(No.2020B121201002).
文摘Coordination chemistry of rare-earth elements has been dominated by the+3 oxidation state.Complexes with higher-valence lanthanide ions are synthetically challenging but are of fundamental research interest and significance as advanced molecular materials.Herein,four tetravalent terbium complexes(2-5)of the common formula[Tb(OSiPh3)4L](L=ethylene glycol dimethyl ether(DME),2,2’-bipyridine(bpy),2,2’-bipyrimidine(bpym),and 1,10-phenanthroline(phen))are reported.Crystallographic analyses reveal in each of these complexes a hexacoordinate Tb(IV)ion situated in a distorted octahedral coordination environment formed by four triphenylsi-loxido ligands and a bidentate chelating ligand.The use of chelating ligands enhances the stability of the resulting complexes over their THF solvate precursor.More significantly,the aromatic N-chelating ligands have been found to tune effectively the electronic structures of the complexes,as evidenced by the sizable potential shifts observed for the quasi-reversible redox Tb(IV/III)process and by the changes in their absorption spectra.The experimental findings are augmented with quantum theoretical calculations in which the ligandπ-donation to the 5d orbitals of the Tb(IV)center is found to be primarily responsible for stability enhancement and the corresponding changes of physical properties observed.Magnetic measurements and results from electron paramagnetic resonance studies produced small absolute values of zero-field splittings of these complexes,ranging from 0.1071(22)to 1.1484(112)cm-1 and comparable to the values reported for analogous Tb(IV)complexes.
