Formation of a Dirhenium Carbene Complex from Reaction of (η⁵-C₅H₄Li)Re(CO)₃with (η⁵-C₅H₅)Re(CO)₃

Abstract

The ring-metalated complex (η5-C5H4Li)Re(CO)3 generated by reaction of (η5-C5H5)Re(CO)3 with n-BuLi in THF at −78 °C reacted with additional (η5-C5H5)Re(CO)3 to produce the dirhenium acyl anion (η5-C5H5)(CO)2Re(CO)[(η5-C5H4)Re(CO)3]-Li+. Protonation of this acyl anion gave the dirhenium hydroxycarbene complex (η5-C5H5)(CO)2ReC(OH)[(η5-C5H4)Re(CO)3], while methylation gave the methoxycarbene complex (η5-C5H5)(CO)2ReC(OCH3)[(η5-C5H4)Re(CO)3], which was characterized by X-ray crystallography. The methoxycarbene complex reacted with n-BuLi to produce the butylcarbene complex (η5-C5H5)(CO)2ReC(CH2CH2CH2CH3)[(η5-C5H4)Re(CO)3].

Reaction of Organolithium Reagents with Tetracarbonyl[2-(phenyl-κC2‘),pyridine-κN]rhenium(I): Isolation and Structural Characterization of Acyl Rhenate Species

“…The 13 C resonances of the acyl carbonyl carbon atoms were detected at 276.1 and 278.9 ppm for PPN- 2a and PPN- 2b , respectively. Similar results for the 13 C resonance of the acyl carbon were reported recently by Casey and co-workers for Li + [(η 5 -C 5 H 5 )(CO) 2 Re(CO)(η 5 -C 5 H 4 )Re(CO) 3 ] - and Li + [(CO) 2 Re(CO)CH 2 CH 2 (η 5 -C 5 H 4 )] - . , Recrystallization of PPN- 2b from pure dichloromethane afforded yellow-orange monoclinic crystals suitable for X-ray diffraction analysis (Figure ).

1 ORTEP drawing and atom-numbering scheme of the molecular structure of 2b .

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Conformational preferences of heteronuclear Fischer carbene complexes of cymantrene and cyclopentadienyl rhenium tricarbonyl

“…The observation of these stretching frequencies are supported by literature [13,14]. NMR spectroscopy indicates downfield-shifted carbene carbon peaks between δ = 269.1 and 331.3 ppm.…”

“…Complexes where MnCp(CO) 3 and ReCp(CO) 3 constitute both the initial building synthons as well as the metallating agent have been studied and published by Fischer [13] and Casey [14] ( Figure 4). Their studies are restricted to either homonuclear carbene complexes or carbene complexes of group VI and according to our knowledge constitute the only other examples where the cymantrene and cyclopentadienyl rhenium substituents serve as both the initial deprotonated moiety and metallating agent.…”

Rhenium-Containing Phosphorus Donor Ligands for Palladium-Catalyzed Suzuki Cross-Coupling Reactions: A New Strategy for High-Activity Systems

“…We also sought reference compounds for 7 with somewhat different electronic properties. Accordingly, (η 5 -C 5 H 5 )Re(CO) 3 was similarly converted to the lithiocyclopentadienyl complex (η 5 -C 5 H 4 Li)Re(CO) 3 ( 9 ) . Subsequent additions of PR 2 Cl gave the target compounds (η 5 -C 5 H 4 PR 2 )Re(CO) 3 ( 10 ; R = a , Ph; b , t -Bu) in 98−30% yields.…”