Constraint of a ruthenium-carbon triple bond to a five-membered ring

Abstract

The first incorporation of a second-row transition metal carbyne unit into a ring is realized by virtue of aromaticity.

Rhodapentalenes: Pincer Complexes with Internal Aromaticity

“…The five occupied π-MOs (highest occupied molecular orbital [HOMO]-1, HOMO-2, HOMO-5, HOMO-10, and HOMO-12) are derived mainly from the orbital interactions between the d -orbitals of the Rh atom (5 d xz and 5 d yz ) and the p zπ orbitals of the C 7 H 5 unit, indicating the involvement of the d -orbitals of the metal center in the π-delocalization along the perimeter of the pincer skeleton. These results are similar to those computed for the osmapentalenes (Zhu et al., 2014) and ruthenapentalenes (Zhuo et al., 2018). However, π-overlaps between the d -orbitals on metal centers and the p -orbital on the carbon atoms of rhodapentalene 2′ are less effective when compared with osmapentalenes (see Figures S9 and S10) and ruthenapentalenes (see Figures S11 and S12).…”

“…More interestingly, dearomatization/aromatization reactions can also be realized in rhodapentalene system. In this context, previous reported metallapentalynes (Zhu et al., 2013, Zhu and Xia, 2018, Zhuo et al., 2018), metallapentalenes (Zhu et al., 2014), and other bridge-headed fused metalla-aromatic compounds (Frogley et al., 2018, Frogley and Wright, 2014, Frogley and Wright, 2017, Wang et al., 2012, Wang et al., 2013) could also be regarded as pincer complexes with internal aromaticity. We believe that these conceptually new pincer complexes, which combine the structural features of both aromatic compounds and rigid pincer complexes would provide new opportunities for pincer chemistry.…”

“…We have recently reported metallapentalenes and metallapentalynes with group 8 metal centers. However, in these complexes the metal-carbon multiple bonds are rather robust (Zhu et al., 2013, Zhu and Xia, 2018, Zhuo et al., 2018). In the case of rhodapentalenes 2 , the metallapentalene chemistry has been extended for the first time from group 8 to group 9 elements.…”

Diphenylamine‐Substituted Osmanaphthalyne Complexes: Structural, Bonding, and Redox Properties of Unusual Donor–Bridge–Acceptor Systems

“…Several types of third‐row late‐transition‐metal heteroaromatic compounds, which includes metallabenzene, metallafuran, metallabenzyne, metallapyridine, metallanaphthalene, metallanaphthalyne, metallapentalynes, metallapentalenes, and their derivatives, have been successfully isolated and characterized in the past decades. A unique cyclic second‐row transition metal carbyne complex (ruthenapentalyne with a very bent Ru≡C−C moiety) has recently been reported by Xia and co‐workers . Displaying both the aromaticity of fused organic heterocyclic compounds and the characteristics of organometallic species, these compounds have attracted the attention of an increasing number of researchers.…”

Access to tetracyclic aromatics with bridgehead metals via metalla-click reactions

“…We thus envisaged that constraining transition metal carbynes into small rings would lead to the activation of the M≡C bond and offer access to the 1,3-dipolar cycloadditions with azides. On the basis of our previous investigation of metallapentalynes (25)(26)(27)(28)(29), the synthesis of the activated M≡C bond within the tricyclic ring system was then targeted, in the hope of obtaining suitable starting material to generate desired tetracyclic aromatic motifs through metalla-click reactions. We reacted complex 1 (27) with K 2 CO 3 (5 eq) at 40°C for 2 days, which afforded a green solution, from which complex 2 was isolated in 84% yield ( Fig.…”