Mono-, di- and tetrarhenium Fischer carbene complexes with thienothiophene substituents. Issue 40 (4th October 2017)

• Record Type: Journal Article
• Authors: Lamprecht, Zandria; Radhakrishnan, Shankara G.; Hildebrandt, Alexander; Lang, Heinrich; Liles, David C.; Weststrate, Nora-ann; Lotz, Simon; Bezuidenhout, Daniela I.
• Is Part Of: Dalton transactions. Volume 46:Issue 40(2017)
• Page Start: 13983
• Page End: 13993
• Publication Date: 2017-10-04
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c7dt02969a
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : Syntheses, spectroelectrochemistry and molecular orbital analyses of mono- to multimetal Re(0) and Re(i ) Fischer carbene complexes with condensed thienothienyl substituents. Abstract : The oxidative cleaving of a rhenium–rhenium bond by bromine in binuclear Fischer carbene complexes proves to be an effective method to prepare mononuclear bromido-carbene complexes. The reaction of mono- and dilithiated thieno[2, 3- b ]thiophene (2, 3- b -TTH2 ) and thieno[3, 2- b ]thiophene (3, 2- b -TTH2 ) with [Re2 (CO)10 ] affords dirhenium nonacarbonyl ethoxycarbene complexes, [Re2 (CO)9 {C(OEt)2, 3- b -TTH}] (1a ) and [Re2 (CO)9 {C(OEt)3, 2- b -TTH}] (1b ), and the tetrarhenium bis(ethoxycarbene) complexes from the dilithiated thiophene substrates, [Re2 (CO)9 -μ-{C(OEt)-2, 3- b -TT-C(OEt)}Re2 (CO)9 ] (2a ) and [Re2 (CO)9 -μ-{C(OEt)-3, 2- b -TT-C(OEt)}Re2 (CO)9 ] (2b ) featuring bridging thiophene linkers. Rhenium–rhenium bond cleavage by bromine of the monocarbene complexes yielded the scarce class of monorhenium bromido-carbene complexes, cis -[Re(CO)4 {C(OEt)2, 3- b -TTH}Br] (3a ) and cis -[Re(CO)4 {C(OEt)3, 2- b -TTH}Br] (3b ), while the corresponding reaction of the biscarbene tetrarhenium carbonyl complex of thieno[2, 3- b ]thiophene afforded the cleaving of both metal–metal bonds to give the novel dirhenium biscarbene dibromido complex with a thienothiophene spacer, [Re(CO)4 Br-μ-{C(OEt)-2, 3- b -TT-C(OEt)}Re(CO)4 Br] (4a ). A new indirect aminolysis route is described to prepare the chlorido dimethylaminocarbene complex5a cis -[Re(CO)4 {C(NMe2 )2, 3- b -TTH}Cl], with unexpected cleavage of the Re–Re bond. Single crystal X-ray diffraction studies were performed on1a, 2a, 3a, 5a, 1b and3b . Spectroscopic and electrochemical methods are employed to investigate the electronic effect of the different conjugation pathways in the different thienothiophenyl carbene substituents, and the replacement of the rhenium pentacarbonyl fragment with a bromido ligand.