STUDIES ON TRANSITION METAL COMPLEXES WITH HYBRID CHELATE LIGANDS

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Transition metal complexes with a P-N,Cp-P,or N-C hybrid chelate ligand were synthesized and their structure and reactivity were examined.(1) As a new type of P-N hybrid chelate ligand, Ph_2-o-C_6H_4CH_2O(CH_2)_n-2-C_5H_3N(n=1,2,3) were prepared and their Pd and Pt complexes were prepared. By adjusting the chelate length cis-or trans-PdCl_2(PN) complexes were selectively obtained. The trans-PdCl_2(PN) is the first example of the transition metal complexes with a bidentatetrans cheate P-N ligand. The Pd(I) complex with the shortest Pd-Pd bond was prepared. Cationic Pt complexes having phosphine ligands were found to be active catalysts for stereoselective addition of alcohol to alkynes to give vinyl ethers or ketones. sigma-Vinyl Pd and Pt complexes having a P-O-N or a P-O-P tridentate ligand were isolated as the reaction intermediate and the reaction pathway was clarified.(2) Optically active Cp-P hybrid ligands connecting a cyclopentadienyl or an indenyl group with PPh_2 by a L-threitol backbone were prepared and their Ru and Rh complexes were prepared. It was found that the Ru complex was an effective catalyst for an asymmetric C-C bond forming reaction from terminal acetylene and allylic alcohol. As achiral Cp-P ligands general synthetic method of CpH(CH_2)_nPPh_2(Cp=C_5H_4 or 1-C_9H_6 ; n=2,3,4) was established and their transition metal chemistry was examined. Stereoselective addition of ethyl iodide to RhCl(CO)(Cp-P)[Cp=1-indenyl] to give one of the two diastereomeric acyl complexes has been achieved. By application of this reaction we will try to prepare a new optically active Cp-P complex having a chiral metal center.(3) A stereoselectve reaction between a Pd complex having an optically active C-N chelate ligand with a racemic phosphole derivative was studied.