Kazumori Kawamura

Early-Transition-Metal Catalysts with Phenoxy–Imine-Type Ligands for the Oligomerization of Ethylene

Early-transition-metal complexes incorporating phenoxy-imine-type bidentate and tridentate ligands, after activation, can achieve selective as well as nonselective ethylene oligomerization to produce 1-hexene, linear α-olefins, and vinyl-terminated low-molecular-weight polyethylenes, all with high efficiency.

Syntheses, structure, and Berry pseudorotation of ruthenium-, iron-, and cobalt-phosphorane complexes

Abstract Transition metal complexes bearing a phosphorane fragment with two 3-methylcatecholate substituents, Cp′(CO)2M{ P(OC 7 H 6 O )2} (Cp′=η5-C5H5, η5-C5Me5; M=Ru, Fe) and L(CO)3Co{ P(OC 7 H 6 O )2} (L=PPh3, PPh2Me), were prepared. The X-ray structure of (η5-C5Me5)(CO)2Ru{ P(OC 7 H 6 O )2} was determined. From the variable-temperature 31P-NMR studies, the activation parameters for Berry pseudorotation around the pentacoordinate phosphorus were determined and discussed.

Conversion of cationic phosphite complexes into phosphonate complexes with selective deamination on the coordinating phosphorus. Reaction of [(η5-C5H5)L2Fe{P(NC4H8)n(OMe)3−n}]+ (LCO, PMe3) with KOH to afford (η5-C5H5)L2Fe{P(O)(NC4H8)n−1(OMe)3−n}

Abstract Amino-substituted phosphite iron complexes, [Cp(CO)2Fe{P(NC4H8)n(OMe)3−n}]+ (n=1−3), react with KOH in H2O at room temperature to give phosphonate complexes, Cp(CO)2Fe{P(O)(NC4H8)n−1(OMe)3−n} with selective deamination. The reactions with KOH of phosphite complexes [Cp(PMe3)2Fe{(P(NC4H8)n(OMe)3−n}]+ which have no carbonyl ligands yield deaminated phosphonate complexes Cp(PMe3)2Fe{P(O)(NC4H8)n−1(OMe)3−n}, indicating the carbonyl ligand is not essential for the phosphite-phosphonate conversion with selective deamination. A reaction mechanism is proposed in which an OH− nucleophilically attacks the coordinating phosphite phosphorus to afford a pentavalent phosphorus intermediate (metallaphosphorane).