Complexes of alkyl and aryl cyanides.  9.  Reactions of cis-tetrachlorobis(acetonitrile)rhenium with bidentate phosphorus and arsenic donors:  cis-trans isomerization in complexes of the type ReCl4L2

Myers, R. E.; Walton, Richard A.

doi:10.1021/ic50166a027

Cited by 13 publications

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“…The new reduction feature observed at −0.4 V is consistent w i t h a p r e v i o u s r e p o r t o f c i s -[ R e C l 4 ( d p p e ) ] (E 1/2 ([ReCl 4 (dppe)] 0/− ) = −0.45 V vs Fc +/0 in DCM). 36 Addition of PPh 3 after reaction with chloride does not reverse this ligand substitution (Figure S35). However, the addition of PPh 3 before the addition of Cl − helps to reduce the displacement of PPh 3 indicated by reduction of the peak currents for the [ReCl 4 (dppe)] 0/− couple at −0.4 V (Figure S37).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…We assigned these two cathodic features to the [ReCl 4 (dppe)] 0/− and [Re-Cl 4 (dppe)] −/2− couples, respectively, as they are consistent with the redox features reported for [ReCl 4 (dppe)] − . 36 The formation of [ReCl 4 (dppe)] − under bulk electrolysis conditions is not surprising, as the reduction of ReCl 3 (dppe)(PPh 3 ) (1dppe) liberates chloride anions, which will readily react with the unreduced amount of ReCl 3 (dppe)(PPh 3 ) to form [Re-Cl 4 (dppe)] − . This self-inhibition pathway helps rationalize the lower yields of ReClCp(H)(2-dppe) formation (∼68%) when either a weaker reductant is used or less cathodic potential is applied (−1.4 V).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…We assign this new species to the rhenium tetrachloride complex [ReCl 4 (dppe)] − (Scheme ). The new reduction feature observed at −0.4 V is consistent with a previous report of cis -[ReCl 4 (dppe)] ( E 1/2 ([ReCl 4 (dppe)] 0/– ) = −0.45 V vs Fc +/0 in DCM) . Addition of PPh 3 after reaction with chloride does not reverse this ligand substitution (Figure S35).…”

Section: Resultsmentioning

confidence: 99%

“…Two additional redox features were also observed in the voltammograms of the bulk electrolysis solution after electrolysis at −1.4 V, with anodic peak potentials at −0.4 and −1.7 V. When a subsequent electrolysis was performed on the same solution at −1.9 V in the presence of CpH, these features were diminished. We assigned these two cathodic features to the [ReCl 4 (dppe)] 0/– and [ReCl 4 (dppe)] −/2– couples, respectively, as they are consistent with the redox features reported for [ReCl 4 (dppe)] − . The formation of [ReCl 4 (dppe)] − under bulk electrolysis conditions is not surprising, as the reduction of ReCl 3 (dppe)(PPh 3 ) ( 1-dppe ) liberates chloride anions, which will readily react with the unreduced amount of ReCl 3 (dppe)(PPh 3 ) to form [ReCl 4 (dppe)] − .…”

Section: Resultsmentioning

confidence: 99%

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Electrosynthetic Route to Cyclopentadienyl Rhenium Hydride Complexes Enabled by Electrochemical Investigations of their Redox-Induced Formation

et al. 2020

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As the utility of electroanalytical methods to study reaction mechanisms continues to develop, a wider scope of chemical reactions will fall under the scrutiny of electrochemical investigation. We report herein thermochemical and electrosynthetic routes to stable rhenium hydride complexes ReClCp(H)(dppx) (dppx = 1,1-bis(diphenylphosphino)methane (dpp m), 1,2-b is(diph enylp hosph ino)eth an e ( dppe ), 1,3-b is-(diphenylphosphino)propane (dppp), Cp = cyclopentadienyl). These complexes are accessed via reduction of the corresponding ReCl 3 (dppx)(PPh 3 ) in the presence of cyclopentadiene, which was initially achieved by a traditional chemical route. Complementary chemical and electrochemical methods were used to elucidate the mechanism by which the rhenium hydride complexes form. Notably, reduction of the Re(III) precursor proceeds via an ECE mechanism, liberating chloride ions that can detrimentally react with unreduced precursor. Further, a pair of key Re(I) intermediates (one with and one without coordinated N 2 ) were isolated and characterized and shown to have dramatic differences in reactivity with CpH. Guided by mechanistic insight, an efficient electrochemical synthesis route was designed through which the rhenium hydride complex is accessed in 96% yield with 90% Faradaic efficiency. While many organometallic complexes have only been accessed with traditional chemical reductants, this work highlights that a detailed mechanistic understanding enables the robust translation of these processes to electrosynthetic reactions.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Electrosynthetic Route to Cyclopentadienyl Rhenium Hydride Complexes Enabled by Electrochemical Investigations of their Redox-Induced Formation

et al. 2020

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Technetium & Rhenium: Inorganic & Coordination Chemistry

Pombeiro¹,

Silva²,

Crabtree

2005

Encyclopedia of Inorganic Chemistry

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The inorganic and coordination chemistry of both rhenium and technetium is described in a condensed way with presentation of significant and typical compounds and reactions and applications in nuclear medicine and catalysis. After an Introduction, with properties of those elements and their sources, a description of binary compounds (for example oxides, sulfides, halides, and nitrides), their syntheses, structures, and selected reactions are given. This is followed by a treatment of the coordination chemistry of those metals, comprising hydrides, metal–metal bonded species and complexes with ligands coordinated by donor‐atoms mainly of the following periodic groups: 15 (commonly nitrogen and phosphorus, including dinitrogen, nitrile, nitric oxide and related ligands, hydrazides, diazenides, nitride, imides, pyrazolylborates, and phosphine ligands), 16 (mainly oxo, thio, and other O‐ or S‐ligands), and 17 (halide ligands); the metal–carbon (group 14) bond complexes are usually not covered since they are dealt with separately. Preparative methods, structures, and reactivities are illustrated for those types of complexes. Selected complexes of 99 m Tc and 186 Re (or 188 Re) are described and their applications in nuclear medicine illustrated, as radiopharmaceuticals normally for clinical diagnosis. The application of inorganic rhenium complexes in catalysis constitutes a currently expanding area of high potential and their use as catalysts for the following reactions is reviewed: oxygen atom transfer (OAT) and related reactions; isomerization or etherification of allylic or propargylic alcohols; Beckmann rearrangement of oximes; dehydration of primary amides and aldoximes; dehydrogenation of alkanes, unconventional reduction of aldehydes and ketones; aldol‐type reactions; and photo‐ and electrocatalytic reduction of carbon dioxide. A few catalytic applications of technetium compounds are also indicated.

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