Synthesis and Reactions of Rhenium(V) Oxo−Hydride Complexes

Abstract

Tp*ReO(H)Cl, TpRe(O)H(Cl), and Tp*ReO(H)2 have been prepared by alkoxide-for-hydride metathesis using BH3·THF. The triflate derivative Tp*Re(O)H(OTf) inserts olefins and is oxidized by oxygen-atom transfer reagents to give HOTf and Tp*ReO3, likely by a pathway involving hydride migration to an oxo ligand (Tp* = hydrotris(3,5-dimethyl-1-pyrazolyl)borate; triflate = OTf = OSO2CF3).

Electrophile-promoted Fe-to-N2hydride migration in highly reduced Fe(N2)(H) complexes

“…Well-studied examples of this reactivity pattern are scarce, with early detailed studies from the Mayer group reporting the migration of a variety of R groups (R = alkyl, aryl, H) to electrophilic Re( O). 25 Perhaps more closely related to the present system, Wolczanski, Cundari, and coworkers very recently reported a four-coordinate Fe( iv ) imido complex that formally inserts into an Fe–R bond (R = neo Pe, 1-nor) to generate a new, three-coordinate Fe( ii ) amido complex ( Scheme 4 ). 26 …”

Synthesis and Reactivity of Aryl- and Alkyl-Rhenium(V) Imido−Triflate Compounds: An Unusual Mechanism for Triflate Substitution

“…The ethylene protons appear as an ABCD pattern (confirmed by decoupling experiments), indicating that ethylene rotation is slow on the NMR time scale at 25 °C. There is a 3 Hz coupling between one of the ethylene protons and the hydride signal at δ = 9.40 ppm, a reasonable chemical shift for a Re(V) hydride ligand . Treatment of 18 with HCl(g) gives TpRe(NTol)Cl 2 , free ethylene, and H 2 , although not quantitatively.…”

“…Apparently the alkyl complexes are more stable than their alkene−hydride tautomers, and alkene dissociation is not facile. Alkene insertion into Tp*Re(O)H(OTf) has been reported …”

Rhenium(V) Dioxo Complexes with Dihydrobis(pyrazolyl)borates: Synthesis and Reactivity toward Electrophilic Substrates

“…With hydrotris- and tetrakis(pyrazolyl)borates a rich and versatile chemistry has been developed for Re(V), Re(VI), and Re(VII). − Some recent examples are the Re(V) and Re(VI) dioxo complexes trans -[ReO 2 {η 2 -RB(pz) 3 }(py) 2 ] (R = H, pz) 24 and cis -[ReO 2 X{η 3 -HB(pz) 3 }] (X = Cl, Br, I) . In contrast, with dihydrobis(pyrazolyl)borates ([H 2 B(pz*) 2 ] - , pz* = pz or substituted pz) the chemistry of rhenium remains rather unexplored.…”