Syntheses, Structures, and Spectro-electrochemistry of {Cp*(PP)Ru}CCCC{Ru(PP)Cp*} (PP = dppm, dppe) and Their Mono- and Dications

M.I. Bruce, B.G. Ellis, P.J. Low, Brian Skelton, Allan White

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The complexes {Cp*(PP)Ru}2(μ-CCCC) (PP = dppm 5a, dppe 5b) have been synthesized from RuCl(PP)Cp* (1a/b) via the corresponding vinylidenes [Ru(CCH2)(PP)Cp*]+ (2a/b), deprotonation (KOBut) to the ethynyls Ru(CCH)(PP)Cp* (3a/b), oxidative coupling ([FeCp2][PF6]) to the bis(vinylidenes) [{Ru(PP)Cp*}2{μ-(CCHCHC)}]2+ (4a/b), and deprotonation [dbu (4a), KOBut (4b)]. Electrochemistry of 5a/b revealed the expected sequence of four 1e redox steps, which occurred at significantly lower E° values than found for the Ru(PPh3)2Cp analogue. Single-crystal X-ray structure determinations are reported for 1a/b, 2a/b, 3a/b, 4a/b, and 5a/b, together with the oxidized products [5b][PF6]n (n = 1, 2). In the monocation [5b][PF6] the Ru−C(1) [1.931(2) Å] and C−C distances [1.248−1.338(3) Å] are intermediate between those found in 5b and the dication [5b]2+. The short Ru−C [1.857(5) Å] and experimentally equal C−C distances [1.269−1.280(6) Å] in [5b][PF6]2confirm the anticipated dicarbene-cumulene structure for the RuCCCCRu bridge.
Original languageEnglish
Pages (from-to)3184-3198
Issue number16
Publication statusPublished - 2003


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