Activation of Dichloromethane by a Bis-NHC Cp*Ru Complex: Formation of a Pentamethyl(chloromethyl)cyclopentadiene Ligand

Andrés G Algarra,Pedro Valerga,Manuel Jiménez-Tenorio,Juan Carlos G Galindo,M Carmen Puerta

doi:10.1021/acs.organomet.1c00340

Abstract

The dinitrogen complex [{Cp*Ru(L)}2(μ-N2)][BPh4]2 (L = bis(3-methylimidazol-2-ylidene) reacts with dichloromethane at room temperature, furnishing the diene derivative [Ru(η4, κ1-Cl-C5Me5CH2Cl)Cl(L)][BPh4] as result of CH2Cl2 oxidative addition and subsequent migration of the chloromethyl group into the Cp* ring. Mechanistic insight provided by DFT computations indicate that while the cleavage of the C–Cl bond is not thermodynamically favored, the subsequent migration step is largely exergonic and thus provides the driving force for the formation of the observed product.

Highlights

Dichloromethane is known to react with coordinatively unsaturated metal centers via oxidative addition of the C−Cl bond to yield chloromethyl complexes.[1−3] There are cases of double C−Cl oxidative addition leading to a variety of possible reaction products.[4]
We have recently reported the synthesis and characterization of the reactive dinitrogen-bridged complex [{Cp*Ru(L)}2(μ-N2)][BPh4]2 ([1][BPh4]2).[7]
We remarked upon the fact that this compound reacts with chlorinated solvents such as dichloromethane and chloroform at room temperature, yielding dark red solutions which display complex NMR spectra

Summary

Introduction

Dichloromethane is known to react with coordinatively unsaturated metal centers via oxidative addition of the C−Cl bond to yield chloromethyl complexes.[1−3] There are cases of double C−Cl oxidative addition leading to a variety of possible reaction products.[4]. Spectra of this compound led to the conclusion that this compound is the result of the activation of a dichloromethane molecule by the coordinatively unsaturated complex [Cp*Ru(L)]+ generated in situ by dinitrogen loss from [1][BPh4]2.

Results

Conclusion