Geometries And Properties Of Bimetallic Bridged Complexes

In recent several decades, there an increasing interests of the properties oftransition complexes. The novel properties of bimetallic transition complexesare different from the properties of mononuclear complex causing by thefeature of geometries. The bimetallic active center could catalyzemultielctronic reactions. And bichelating ligand could keep the catalyzingunits unitary.In the research, the geometries and the bond properties centroidfour-membered ring in the bimetallic bridged complexes LZn(μ-X)₂ZnL(X=H, F, Cl, Br, OH, OMe, L={HC(CMeNPh)₂}) are been studied.After analyzing the optimized molecular configuration and the results ofNBO and AIM, there are some rules we figures:There is a four-membered ring in the center of the complexes. Theinteraction between zinc atom and ligand is the type of donor-acceptor.The distances between two zinc atoms are close to the twice of zinccovalent radii in the hydro-bridged complexes. The bond order of zinc-zincbond is 0.5334. There is a weak interaction between two zinc atioms. As thesum of distances of bond critical points and bond-side atom are bigger than thebond length, Zn-H bond is bend.As the increasing atomic number of bridged atom in halo-bridgedcomplexes, the atomic radii of the ligand, Zn-Zn distance, Zn-X bond lengthare also increasing, while the Zn-N bond length is decreasing. Accordingly thebond order of Zn-X is decreasing, while that of Zn-N bond is increasing. Theligand atoms are prefer leaving the center of the complex, and the nitrogenatoms are getting closer to the center. The stabilization energies between donorand acceptor orbitals are getting higher, which shows the degree ofdelocalization are bigger. As the decreasing electron density of ring criticalpoints, Zn₂H₂ four-membered ring are weaker. The geometry information indicates the four-membered rings ofoxo-bridged complexes are folded. As the radical bonded to the oxygen atomsbecome bigger, the Zn-O bond length is decreasing, while Zn-N bond length isincreasing. Accordingly, the bond order of Zn-O bond is increasing while thatof Zn-N bond is decreasing. The stabilization energies between donor andacceptor orbitals are increasing slightly, which means the degree ofdelocaliztion are bigger. Because of the deceasing electron density of ringcritical point, the four-membered ring is weaker.