Novel Amidoniobium Complexes with a Functional Relationship to the [Cp2ZrR]+ Ion*

Abstract

Partial abstraction of apical methyl groups is observed in aminopyridinatoniobium alkyne complexes, as exemplified with the synthesis and characterization of 1. This results in cationic complex fragments, which facilitate the polymerization of ethylene and in the presence of methylalumoxane the selective dimerization of 1-butene.

Synthesis and Structural Analysis of Four Coordinate (Arylimido)niobium(V) Dimethyl Complexes Containing Phenoxide Ligand: MAO-Free Ethylene Polymerization by the Cationic Nb(V)–Methyl Complex

“…Synthesis and reaction chemistry of the high oxidation state group 5 organometallic complexes have been considered as an important subject in organometallic chemistry as well as in catalysis . The study should be helpful not only for better understanding of the organometallic chemistry but also for design of efficient and unique molecular catalysts, because of their potentials as promising reactivity demonstrated in classical Ziegler type vanadium catalyst systems for olefin polymerization , and as reports in polymerization of disubstituted acetylenes mostly demonstrated by niobium and tantalum catalyst systems or niobium–, tantalum–alkylidene complex catalysts. − Although the metal–alkyl complex plays an important role in olefin coordination polymerization that has been known as the key reaction in production of polyolefins [linear low density (or high density) polyethylene, isotactic polypropylene], ,,, however, the reported examples by the niobium complex catalysts (exemplified in Chart A–K) − have been less compared to those by the vanadium complex catalysts , as well as the group 4 transition metal complex catalysts. , On the basis of reported results, niobium complexes should have certain potentials, because Cp*NbCl 2 (η 4 -diene) (A) and Cp*Nb­(η 4 -diene) 2 enable living ethylene polymerization in the presence of methylaluminoxane (MAO) to proceed . Moreover, the complexes containing chelate imino ligands (G, H) exhibited high catalytic activities for ethylene polymerization upon addition of halogenated Al alkyls and chlorinated reoxidant (ethyl trichloroacetate); the dichloride complex containing amine triphenolate ligand, NbCl 2 [(O-2,4- t Bu 2 C 6 H 2 -6-CH 2 ) 3 N] (K), exhibited high activities in the presence of MAO at 100, 120 °C .…”

Synthesis and Structure of the Dimeric Copper(II) Complex Tetrakis[N-thiazol-2-yl-(4-methylphenyl)sulfonamidate]dicopper(II)

“…The sulfathiazolato anions act as bridges linking to one copper(II) ion through the N thiazole atom and to the other copper(II) ion by means of the N sulfonamide atom. The copper atom labeled as Cu( 1) is bonded to N (21) and N(31) thiazole nitrogen atoms from two molecules of sulfathiazolato ligands and N (12) and N(42) from the other two sulfathiazolato anions; the Cu(2) enviroment is similar, with bonding to N (11) and N(41) of the thiazole rings and N(22) and N(32) of the sulfonamido groups, in such a way that the disposition is trans in both cases. The internal geometry of the sulfathiazole ligand is normal and is consistent with the results from numerous studies performed previously.…”

“…In addition, the presence of a heterocyclic ring with potential donor atoms would increase the coordination ability. In this respect the most widely explored system is the pyridine ring [7][8][9][10][11][12][13][14].…”

Crystal structure of bis-(2,4,6-trimethylphenyl)-[6-(2,4,6-trimethylphenyl) pyridin-2-yl]amido-(μ-oxo)-hexachloroditantalum(V), (C46H50N4)Ta2Cl6O

“…In our previous work we reported on organo group 5compounds stabilized by aminopyridinato ligands [1,2]. The title complex is an oxygen bridged bimetallic tantalum complex.…”