43 research outputs found
Coinage MetalâEthylene Complexes Supported by Tris(pyrazolyl)borates: A Computational Study
Probing Intermetallic Coupling in Dinuclear N-Heterocyclic Carbene Ruthenium(II) Complexes
Synthesis and structure of a bis-N-heterocyclic carbene complex of uranium tetrachloride exhibiting short ClâŻCcarbene contacts
Probing intermetallic coupling in dinuclear N-heterocyclic carbene ruthenium(II) complexes
A series of bimetallic N-heterocyclic carbene (NHC) ruthenium(II) complexes were synthesized, which comprise two [RuClâ(cymene)(NHC)] units that are interlinked via the NHC nitrogens by alkyl chains of different length. Electrochemical characterization revealed two mutually dependent oxidation processes for the complex with a methylene linker, indicating moderate intramolecular electronic coupling of the two metal centers (class II system). The degree of coupling decreases rapidly upon increasing the number of CHâ units in the linker and provides essentially decoupled class I species when propylene or butylene linkers are used. Electrochemical analyses combined with structural investigations suggest a through-bond electronic coupling. Replacement of the alkyl linker with a p-phenylene group afforded cyclometalated complexes, which were considerably less stable. The electronic coupling in the methylene-linked complex and the relatively robust NHCâruthenium bond may provide access to species that are switchable on the molecular scale
Bonding of imidazol-2-ylidene ligands in nickel complexes
The bonding of imidazol-2-ylidenes (H2Im) in a series of nickel complexes with seemingly different complex fragment group electronegativities, i.e., [Ni(H2Im)3], [Ni(H2Im)2], [Ni(H2Im)(CO)], [Ni(H2Im)(CO)2], and [Ni(H2Im)(CO)3], was analyzed. This series provides theoretical evidence that the bonding of imidazol-2-ylidene ligands to metalâcomplex fragments strongly depends on the nature of the ligand environment of the metal complex. An analysis of a series of isostructural complexes D2h- and D2d-M(H2Im)2 with different metals (M = Ni, Pd, Pt) reveals that the bonding also strongly depends on the metal used in the complex