Amphoteric Allenylidene Ruthenium Complexes and the First Dinuclear Ruthenium Species with a Bis-alkenyl Carbyne Bridging Ligand

Abstract

Cationic ruthenium(II) allenylidenes trans-[Cl(dppe)2RuCCC(CH3)R]BF4 (R = Ph, CH3) can be deprotonated to generate neutral alkenyl acetylide metal trans-[Cl(dppe)2Ru−C⋮C−C(CH2)R] or protonated with HBF4·Et2O to lead to dicationic ruthenium(II) carbynes trans-[Cl(dppe)2Ru⋮C−CHC(CH3)R](BF4)2. The latter reaction was applied to transform a conjugated bis-allenylidene bridged diruthenium complex, trans-[Cl(dppe)2RuCCC(CH3)-p-C6H4−(CH3)CCCRu(dppe)2Cl](BF4)2, into the first bis-alkenyl carbyne ruthenium species trans-[Cl(dppe)2Ru⋮C−CHC(CH3)-p-C6H4−(CH3)CHC−C⋮Ru(dppe)2Cl](BF4)4.

Metal Vinylidenes and Allenylidenes in Catalysis: Applications in Anti‐Markovnikov Additions to Terminal Alkynes and Alkene Metathesis

“…[217,[225][226][227] In contrast, Cb is nucleophilic and is readily protonated to give alkenyl carbyne metal complexes. [228,229] Only recently have metal allenylidene complexes or metal allenylidene intermediates, generated in situ by activation of propargyl alcohol derivatives, emerged as catalyst precursors or catalyst intermediates. [43] Significant advances were recently made in the direct propargylation of a variety of substrates by propargyl alcohols [230][231][232][233] and in alkene metathesis promoted by ruthenium allenylidene complexes.…”

Reaction of the RuTp(PR3)Cl fragment with alkynols: Formation of carbene, vinylidene, allenylidene, and carbyne complexes

“…The two Ru-N(Tp) bond lengths cis to the carbene moiety are significantly shorter (Ru-N(2) = 2.087(2) Å , Ru-N(4) = 2.107(2) Å ) than that trans to the carbene unit (Ru-N(6) = 2.233(2) Å ) due to the strong trans influence of the strong p-accepting carbene. The Ru-C(28) bond distance is 1.921 (2) While many allenylidene complexes, especially if they are cationic, add nucleophiles either at the C a or C c carbon atom, electron-rich allenylidene complexes, particularly neutral ones, are capable of adding electrophiles at the C b carbon atom thereby forming vinylcarbyne complxes [16]. Accordingly, we investigated the reaction of the allenylidene complexes 3a-c with CF 3 COOH.…”

Charge localization on a redox-active single-molecule junction and its influence on coherent electron transport

“…We chose this particular system because it was used in previous conductance measurements 22,23 as a monomer of chains -albeit with different anchor groups -where it was found that depending on the chain length either coherent transport or electron hopping is observed 22 . In addition spectroscopic and quantum chemical studies on similar Ru complexes [24][25][26][27][28] suggest that this molecular species offers the possibility to easily link two carbon-rich chains to each other for the formation of reversible redox systems [29][30][31] with distinct optical transition properties 32,33 , thereby serving as a starting point for the investigation of chains with multiple redox active centers 27 . In contrast to Ref.…”