Journal ArticleDOI
Effect of ligand modification on the reactivity of phosphinoamide-bridged heterobimetallic Zr/Co complexes
TLDR
The effect of modifying the N-aryl substituent of the phosphinoamide ligands linking Zr and Co in tris(phosphinoamide)-linked heterobimetallic complexes has been investigated and reveals similar structural features but with a less sterically hindered Zr apical site in complex 4.Abstract:
The effect of modifying the N-aryl substituent (aryl = mesityl vs. m-xylyl) of the phosphinoamide ligands linking Zr and Co in tris(phosphinoamide)-linked heterobimetallic complexes has been investigated. Treatment of the metalloligand (iPr2PNXyl)3ZrCl (2) (Xyl = m-xylyl) with CoI2 affords the iodide-bridged product ICo(iPr2PNXyl)2(μ-I)Zr(η2-iPr2PNXyl) (3) rather than the C3-symmetric isomer observed using the N-mesityl derivative, ICo(iPr2PNMes)3ZrCl. Upon two-electron reduction of complex 3, ligand rearrangement occurs to generate the three-fold symmetric reduced complex N2Co(iPr2PNXyl)3Zr(THF) (4). Comparison of 4 with the previously reported mesityl-substituted complex N2Co(iPr2PNMes)3Zr(THF) (1) reveals similar structural features but with a less sterically hindered Zr apical site in complex 4. An obvious electronic difference between these two complexes is also present based on the drastically different infrared N2 stretching frequencies of 1 and 4. These notable differences lend themselves to different reactivity in both stoichiometric and catalytic reactions. Alkyl halide addition to complex 4 results in homo-coupling products resulting from alkyl radicals rather than the alkyl-bridged or intramolecular C–H activation products formed upon addition of RX to 1. This difference in reactivity with alkyl halides renders complex 3 a less effective catalyst for the Kumada cross-coupling of alkyl halides with n-octylMgBr than ICo(iPr2PNMes)3ZrCl, as a greater proportion of homocoupling products are formed under catalytic conditions.read more
Citations
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Paramagnetic Metal-Metal Bonded Heterometallic Complexes.
Jill A. Chipman,John F. Berry +1 more
TL;DR: This Review focuses in this Review on the synthetic methods employed to access multimetallic coordination complexes with heterometallic metal-metal bonds that are paramagnetic, and the magnetic properties of these compounds can be described using an extension of the Goodenough-Kanamori rules.
Journal ArticleDOI
Cooperative H2 Activation across a Metal–Metal Multiple Bond and Hydrogenation Reactions Catalyzed by a Zr/Co Heterobimetallic Complex
TL;DR: In the quest for active and selective catalysts featuring nonprecious metals, bimetallic cooperativity poses a unique opportunity to promote catalytic reactions and influence selectivity.
Journal ArticleDOI
Heterobimetallic Ti/Co Complexes That Promote Catalytic N–N Bond Cleavage
TL;DR: Complexes 4, 5, and 6 have been shown to catalyze the disproportionation of hydrazine into ammonia and dinitrogen gas through a mechanism involving a diazene intermediate.
Journal ArticleDOI
Origin of Fast Catalysis in Allylic Amination Reactions Catalyzed by Pd–Ti Heterobimetallic Complexes
Whitney K. Walker,Benjamin M. Kay,Scott A. Michaelis,Diana L. Anderson,Stacey J. Smith,Daniel H. Ess,David J. Michaelis +6 more
TL;DR: Computational and experimental studies demonstrate that the Pd-Ti interaction induces and is responsible for significantly lower barriers and faster catalysis for allylic aminations.
References
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