Transition Metal Alkyl Complexes: Oxidative Addition and Insertion

Insertion Reactions of Tantalum(V) Carborane Alkyl and Aryl Complexes with Nitriles and Isonitriles. Thermal and Photochemical Isomerization of η2-Iminoacyl Isomers1

“…Similarly, complexes 5a and 5b do not react with excess t-BuNC at room temperature but do undergo reaction upon photolysis to give several products, which were also shown by mass spectrometry to incorporate one additional equivalent of isocyanide. In contrast to the facile reaction of both neutral and cationic group 4 metallocene alkyls with alkynes, [21][22][23][24][25][26][27][28][29][30] (carborane)CpTa complexes 1-3 are inert toward simple alkynes at elevated temperatures. Instead, insertion chemistry is photochemically driven.…”

“…In contrast to the facile reaction of both neutral and cationic group 4 metallocene alkyls with alkynes, − (carborane)CpTa complexes 1 − 3 are inert toward simple alkynes at elevated temperatures. Instead, insertion chemistry is photochemically driven.…”

Kinetics of the Oxidative Addition ofortho-Substituted Aryl Halides to Palladium(0) Complexes

“…Phosphane-monoligated complexes 2 are formed in the case of a bulky ligand L ϭ P(o-tolyl) 3 and a C(O)Me substituent, which is able to coordinate the Pd II center by the O atom. (4) Whereas reactions of ortho-substituted aryl halides with nucleophiles (alkynes, [12,13] alkenes, [13,14] organometallic reagents [6,15] ) are catalyzed by Pd 0 complexes, reactions involving substituted arenes cannot be catalyzed by Pd II complexes able to activate the initial substituted arene, unless the Pd 0 complex generated in the last step [4,7,16] is oxidized back to a Pd II complex. To the best of our knowledge, the recycling of the Pd II catalyst by oxidation has not yet been realized.…”

Kinetics of the Oxidative Addition of ortho-Substituted Aryl Halides to Palladium(0) Complexes

“…Phosphane-monoligated complexes 2 are formed in the case of a bulky ligand L ϭ P(o-tolyl) 3 and a C(O)Me substituent, which is able to coordinate the Pd II center by the O atom. (4) Whereas reactions of ortho-substituted aryl halides with nucleophiles (alkynes, [12,13] alkenes, [13,14] organometallic reagents [6,15] ) are catalyzed by Pd 0 complexes, reactions involving substituted arenes cannot be catalyzed by Pd II complexes able to activate the initial substituted arene, unless the Pd 0 complex generated in the last step [4,7,16] is oxidized back to a Pd II complex. To the best of our knowledge, the recycling of the Pd II catalyst by oxidation has not yet been realized.…”