H2 Activation and Direct Access to Terminal Nitride and cyclo-P3 Complexes by an Acceptor-Free Rhenium(II) β-Diketiminate

Trevor D Lohrey; Guodong Rao; R David Britt; Robert G Bergman; John Arnold

doi:10.1021/acs.inorgchem.9b02556

H₂ Activation and Direct Access to Terminal Nitride and cyclo-P₃ Complexes by an Acceptor-Free Rhenium(II) β-Diketiminate

Inorg Chem. 2019 Oct 7;58(19):13492-13501. doi: 10.1021/acs.inorgchem.9b02556. Epub 2019 Sep 24.

Authors

Trevor D Lohrey^{1

2}, Guodong Rao³, R David Britt³, Robert G Bergman¹, John Arnold^{1

2}

Affiliations

¹ Department of Chemistry , University of California , Berkeley , California 94720 , United States.
² Chemical Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States.
³ Department of Chemistry , University of California , Davis , California 95616 , United States.

PMID: 31550147
DOI: 10.1021/acs.inorgchem.9b02556

Abstract

The rhenium(II) complex Re(η⁵-Cp)(BDI) (B; BDI = N,N'-bis(2,6-diisopropylphenyl)-3,5-dimethyl-β-diketiminate; Cp = cyclopentadienyl) was subjected to a number of reactivity studies that highlight its unique combination of oxidation state and acceptor-free coordination environment. In the reactions under study we found that this low-valent paramagnetic species yields diamagnetic rhenium(III) or rhenium(V) products, indicating a combination of reducing power and radical character are the primary variables that control its reactivity. Namely, B has been found to promote the cleavage of dihydrogen to yield the rhenium(III) hydride Re(H)(η⁵-Cp)(BDI) (C), as well as the three-electron reduction of organic azides to yield a rhenium(V) terminal nitride complex NRe(η³-Cp)(BDI) (3), which features a low-hapticity Cp ligand. Additionally, we found that B readily activates white phosphorus (P₄) to form the rhenium(V) cyclo-P₃ complex (cyclo-P₃)Re(η⁵-Cp)(BDI) (4). One-electron oxidation of 4 gave the paramagnetic rhenium(VI) salt [(cyclo-P₃)Re(η⁵-Cp)(BDI)][OTf] (5-OTf), which was characterized by electron paramagnetic resonance and electron-nuclear double resonance spectroscopy spectroscopies. Density functional theory calculations and X-ray crystallography also provided a useful basis for understanding the reactivity and electronic structure of B and its derivatives.