Study On Metal Complexes Supported By Unsymmetrically Substituted Diarylmethyl Phenolates

The thesis reports the synthesis of a series of phenolate/alkyl mixed ligands[^ROC]^2-and their corresponding alkali metal complexes,as well as the utilization of lithium complex Li₂[^ROC]?Et₂O?_n?R=H?5-H?,Me?5-Me?,^tBu?5-^tBu?,Ph?5-Ph?;n=0,1,2?as transmetallation reagents for the preparation of other metal?Mg,Zn,Sn,Ir,Fe,Co,Ni?alkyl/aryloxide complexes.The composition and purity of the organic ligands were confirmed by ¹H NMR methods.The composition and structure of metal complexes were systematically determined by nuclear magnetic resonance spectroscopy,single crystal X-ray diffraction,IR,UV-vis spectroscopy,cyclic voltammetry?CV?and elemental analysis.The main research work is as follows:?1?A series of ortho-diarylmethyl-substituted phenols were prepared through substituent modification to regulate their steric hindrance and electronic property.Furthermore,the deprotonation reaction of these phenols were investigated with various alkali metal reagents.When a less basic reagent?e.g.KN?Si Me₃?₂?was employed,only the proton of the phenolic hydroxyl group is removed,yielding an alkali metal compound with a monoanionic phenolate ligand.In contrast,when a sufficient amount of strong bases ⁿBu Li or ⁿBu Li/Na O^tBu were used,both protons of the phenolic hydroxyl groups and diarylmethyl substituents can be removed to form alkali metal complexes supported by dianionic trityl/aryloxide ligands.The crystal structures of these alkali metal complexes indicate that the central carbon atom of the metal-bound triarylmethyl group adopts sp²hybridization.UV-vis spectroscopy shows that[^ROC]^2-alkali metal complexes have absorption peaks at 420?436 nm,which are consistent with the red color shown by the compounds.The redox potential of 5-H was determined by cyclic voltammetry,and its reactivity with Ph ICl₂was further used to elucidate the redox properties of the[^HOC]^2-ligand.?2?Alkyl/aryloxo complexes of the main group elements?i.e.Mg,Zn,Sn?were synthesized through salt metathesis route.Their single crystal structure show that the ligands chelate the metal centers through the carbon atom of the triarylmethyl group and the oxygen atom of the aryloxide group??²-O,C mode?,forming complexes with formula of{M[^ROC]?THF?}₂?7-H?M=Zn,R=H?,7-Me?M=Zn,R=Me?,8-H?M=Mg,R=H??and Sn[^HOC]₂?9-H?.The crystal structures of 7-H,7-Me and 8-H are centrosymmetric,with two metal centers and two phenolic oxygen atoms forming a four-membered ring.The Sn center of 9-H is four-coordinated in a distorted tetrahedral geometry??₄=0.67?,which reflects a large steric repulsion between the ligands.?3?Complexes of transition metals?Ir,Fe,Co and Ni?supported by phenolate/alkyl ligands were synthesized.In the Cp*Ir[^MeOC]?Cp*=?⁵-C₅Me₅?complex 10-Me,the Ir center is coordinated with the carbon atoms of the triarylmethyl group in an?³fashion.In contrast,in the iridium compound Cp*Ir[^PhOC]?10-Ph?,the ligand undergoes ring-closing rearrangement during the metal coordination process to obtain a ligand containing cyclohexadiene structural motif.In addition to its coordination with the cyclopentadienyl group,the iridium center also bonds to the two double bonds of cyclohexadiene in an?⁴manner.The crystal structures of M[^{t Bu}OC]₂?M=Fe?11-^tBu?,Co?12-^tBu?,Ni?13-^tBu??are similar.The metal centers are coordinated with one carbon atom from a phenyl ring of the trityl group,in addition to the?²-O,C ligation with the alkyl/aryloxo ligands.There are three possible electronic structures for the iron,cobalt and nickel compounds?11-^tBu,12-^tBu,13-^tBu?:1)metal?II?centerwith two monoanionic radical anions;2)metal?III?center with one monoanionic radical anion and one dianionic ligand;3)metal?III?center with two fully delocalized ligands?average 1.5 negative charge each?.