The Odd Bit of Carbon

Planar Four‐Coordinate Boron: A Single, Flat Boron Atom as a Ligand for Four Metals

“…This concept has thus underpinned the discovery of compounds with planar four-coordinate carbon atoms (A-D, Figure 1). [6][7][8] While research into transitionmetal complexes featuring carbido ligands (a single carbon atom) has been sustained, [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] and in many cases compounds containing planar carbon involve a certain degree of metalation of the carbon atom, examples containing four metalcarbon bonds to the central atom are still exceedingly rare (for example, complex A, Figure 1). [6] Of the theoretical studies on planar tetracoordinate firstrow main-group elements, only Schleyer and co-workers considered boron analogues.…”

Ein planar vierfach koordiniertes Boratom als Ligand für vier Metalle

“…Au-Cl-Bindungen [40] und in ihrem Lewis-sauren Verhalten gegenüber der Metallbase [Pt(PCy 3 )] (unter Bildung von 2, Abbildung 2) zum Ausdruck kommt. [41] Überraschenderweise führt die Zugabe eines ¾quivalents [(ITol)AuCl] (ITol = N,N'-Bis(4methylphenyl)imidazol-2-yliden) zu einer Lçsung von 2 zu einer Tieffeldverschiebung des 11 242 ppm beobachtet, das den CO-Kohlenstoffatomen zugeordnet werden kann.…”

Borido complexes via intermetallic metalloborylene transfer

“…The carbido ligand, a single carbon atom bound to one or more transition metals, is the smallest possible organometallic building block and as such attracts a great deal of fundamental interest. [1][2][3][4][5] Surface carbido ligands appear as poorly-defined intermediates in heterogeneously catalysed processes 6,7 and a carbido complex has been isolated as a decomposition product of a Grubbs-type olefin metathesis catalyst. 8 Despite their apparent simplicity, successful syntheses of carbido complexes are rare.…”

“…Multimetallic, molecular carbido complexes have been constructed using a variety of synthetic strategies, including reduction of halocarbenes, C-O and C-C triple bond metathesis, nucleophilic attack at, and by, a metal-bound carbon atom, and other bridging ligand rearrangements. 5,[9][10][11][12][13][14][15][16][17][18] Similarly, transition metal complexes featuring a single boron atom (borido complexes) are rare, and in contrast to carbido chemistry, 15 no terminal (''naked'') boride complex has yet been synthesised. Dinuclear borido or metalloborylene complexes are available via a number of methods (Fig.…”

“…3). The tetranuclear complex [{(Z 5 Additionally, the Rh2-centre is linked via two bridging carbonyls to the {(Z 5 -C 5 Me 5 )Fe1}-and one bridging carbonyl to the {(Z 5 -C 5 Me 5 )Fe2}-fragments. The overall bonding situation of the central boron atom resembles that of metal base-stabilised metalloborylenes.…”