Consanguineous Families of Coordinated Carbon: A ReC4Re Assembly That Is Isolable in Three Oxidation States, Including Crystallographically Characterized ReC 详细信息    查看全文

• 作者：Monika Brady ; Weiqing Weng ; Yuanlin Zhou ; Jeffery W. Seyler ; Angelo J. Amoroso ; Atta M. Arif ; Marlis Bö ; hme ; Gernot Frenking ; and J. A. Gladysz
• 刊名：Journal of the American Chemical Society
• 出版年：1997
• 出版时间：January 29, 1997
• 年：1997
• 卷：119
• 期：4
• 页码：775 - 788
• 全文大小：571K
• 年卷期：v.119,no.4(January 29, 1997)
• ISSN：1520-5126

文摘

Reaction of(⁵-C₅Me₅)Re(NO)(PPh₃)(CCH)and Cu(OAc)₂ (1.5 equiv, 80 C, pyridine) gives theorange-brown ReC₄Re complex(⁵-C₅Me₅)Re(NO)(PPh₃)(CCCC)(Ph₃P)(ON)Re(⁵-C₅Me₅)(2, 88%) as a 50:50diastereomer mixture. Crystallization affords(SS,RR)-2·2CH₂Cl₂and solutions enriched in (SR,RS)-2(meso). Additionof Ag⁺PF₆^- (2 equiv)yields deep blue (SS,RR)- and(SR,RS)-2²⁺2PF₆^-(86%), which give two geometric isomers(62:38, 89:11; CD₂Cl₂, -93 C) aboutthe ⁺Re=C=C=C=C=Re⁺linkages. Crystal structures of(SS,RR)-2·2CH₂Cl₂ and(SS,RR)-2²⁺2PF₆^-show ReC₄Re units with bond angles (169-178˚) andlengths (CC, 1.202(7); C-C1.398(5); C=C 1.260-1.305(10) Å) near those of butadiyneor cumulenes. Natural bond order analysis andtopologicalelectron density calculations confirm the valence formulations.Reactions of (SS,RR)-2 with(SS,RR)-2²⁺2PF₆^-orAg⁺PF₆^- (1 equiv) give agreen radical cation(SS,RR)-2⁺PF₆^-( = 1.74 _B; Faraday method). Edata yield a K_cvalue of 1.1 × 10⁹ (CH₂Cl₂,22.5 C) for the comproportionation. ESR spectra show undecetswith A_iso,Re values(98 G) half those of related monorhenium radical cations, indicatingspin delocalization over two rheniums (I =5/2). Accordingly, IR spectra give only one _NOband, positioned between those of 2 and2²⁺2PF₆^-(CH₂Cl₂, 1665vs 1623/1719 cm^-1). Near IR spectra showunique solvent-independent bands (883, 1000, 1200 nm; 15000,9400,3200 M^-1 cm^-1).Sodium naphthalenide reduces (SS,RR)- or(SR,RS)-2⁺PF₆^-to (SS,RR)- or (SR,RS)-2, establishingconfigurational stability. These and related data are analyzed indetail.