A STUDY ON CATALYTIC ACTIVITIES OF ORGANOMETALLIC COMPLEXES BEARING TRIS (PYRAZOLYL) BORATE LIGANDS

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1.Stereoregular Polymerization of Phenylacetylenes Catalyzed by [Hydrotris (pyrazolyl) borato] rhodium ComplexesRhodium (I) tris (pyrazolyl) borate complexes Tp^<R2>Rh (cod) (R=Me, Ph, i-Pr) were found to serve as efficient catalysts for highly stereoregular polymerization of phenylacetylene derivatives (p-YC_6H_4C=CH : Y=H,Me, Cl, CN,CO_2Me, COMe, NO_2) to give poly (phenylacetylene) s having a head-to-tail, cis-transoidal structure.2.Ring-opening Metathesis Polymerization of Norbornene Derivatives Catalyzed by Vinylideneruthenium ComplexesA vinylideneruthenium complex bearing a hydrotris (pyrazolyl) borate ligand serves as a good catalyst precursor for the ring-opening metathesis polymerization of norbornene derivatives. The catalytic activity is efficiently enhanced by adding Lewis acid such as BF_3・Et_2O to the system. The catalytic activities of related vinylidene complexes having tertiary phosphine ligands are also examined.3.Synthesis and Reactions of (pi-Allyl) bromo [hydrotris (3,5-dimethylpyrazolyl) borato] rthodiumThe complex Tp^<Me2>Rh (coe) (MeCN) has been found to undergo the oxidative addition of allyl bromide to give a pi-allyl complex Tp^<Me2>Rh (pi-allyl) Br, which exhibits high reactivity toward MeMgBr and Li [BHE_<t3>] to give Tp^<Me2>Rh (pi-allyl) Me and Tp^<Me2>Rh (pi-allyl) H,respectively. The latter is formed mainly by nucleophilic addition of H-to the central carbon of the pi-allyl ligand followed by beta-hydrogen elimination of the resultant rhodacyclobutane intermediate.4.Synthesis of Alkyl [hydrotris (pyrazolyl) borato] ruthenium (II) Complexes by TransmetallationAlkylation of [Ru (tp) Cl (cod)] (Tp=hydrotris (pyrazolyl) borate) with AlR_3 (R=Et, Me) successfully proceeded in a benzene or toluene solution at room temperature to give the corresponding [Ru (tp) R (cod)] complexes (R=Et, Me) in high yields.