Reactivity of the polyhydride complexes [ReH5(PPh3)3], [ReH3(dppe)2](dppe = Ph2PCH2CH2PPh2), [ReH3(PPh3)3L], and [ReH4(PPh3)3L]PF6(L = MeCN or ButNC) towards electrophiles and nucleophiles

Abstract

Protonation of [ReH₅(PPh₃)₃] with HBF₄ in CH₂Cl₂ gives yellow [ReH₆(PPh₃)₃] BF₄, whereas its treatment with C₇H₇⁺PF₆^– in the presence of various ligands leads to formation of the compounds [ReH₄(PPh₃)₃L] PF₆ where L = MeCN, PPh₃, Bu^tNC, or 2,6-Me₂C₆H₃NC. Deprotonation of the complexes where L = MeCN or Bu^tNC was accomplished using NEt₃ to form the neutral trihydrides [ReH₃(PPh₃)₃(NCMe)] and [ReH₃(PPh₃)₃(CN Bu^t)]. Protonation of [ReH₃(PPh₃)₃(NCMe)] with HBF₄ in MeCN reforms [ReH₄(PPh₃)₃(NCMe)]⁺, whereas with C₇H₇⁺PF₆^– in MeCN the dihydride [ReH₂(PPh₃)₃(NCMe)₂] PF₆ is produced; a second equivalent of C₇H₇⁺ PF₆^–(in MeCN) results in the formation of [ReH (PPh₃)₃(NCMe)₃][PF₆]₂. The complex [ReH₃(PPh₃)₃(CNBu^t)] reacts with C₇H₇⁺ PF₆^– and MeCN in a similar fashion to [ReH₃(PPh₃)₃(NCMe)] to produce [ReH₂(PPh₃)₃(NCMe)(CNBu^t)] PF₆, but when it is treated with HBF₄ and MeCN the protonated isocyanide complex [ReH₂(PPh₃)₃{CN(H) Bu^t}(NCMe)][BF₄]₂ is isolated. Furthermore, [ReH₃(dppe)₂](dppe = Ph₂PCH₂CH₂PPh₂) reacts with C₇H₇⁺PF₆^– in the presence of MeCN, Bu^tNC, or 2,6-Me₂C₆H₃NC to produce complexes of the type [ReH₂(dppe)₂L] PF₆.