Pentaatomic Tetracoordinate Planar Carbon, [CAl4]2−: A New Structural Unit and Its Salt Complexes

Abstract

The novel charge‐transfer salt Na+[CAl42−] was produced and characterized in the gas phase. The CAl42− dianion contains a tetracoordinate planar carbon center (see picture), and the Na+ ion is coordinated to an edge of the dianion. The four‐center peripheral ligand–ligand bond that is responsible for the planarity of CAl42− is retained in the presence of the countercation; this provides the opportunity to design new bulk ionic materials with CAl42− as a novel structural unit.

Origin of the Formation of Nanoislands on Cobalt Catalysts during Fischer–Tropsch Synthesis

“…Chemical bonding in metal clusters containing square-planar carbon is wellunderstood, and the hunt for clusters containing square-planar C, N, and Si is indeed very active. [33][34][35][36][37] Here we demonstrate that the stability of this unusual square-planar carbon also plays a crucial role in the structure and activity of industrial catalysts.…”

“…Its 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 stability and bonding pattern furthermore suggests that this unique role is not limited to cobalt and should also be explored, e.g., for Ni, Fe, Rh, and Pd. [33][34][35][36][37] The Co 2p binding energy at the C/CO-covered step sites, 779.6 eV, is typical for oxidized Co species and could be a fingerprint for the predicted structures. The eventual shape and size of the nano-islands also depends on the stability and coverage of corner sites, and is likely a strong function of the reaction conditions.…”

Be2C Monolayer with Quasi‐Planar Hexacoordinate Carbons: A Global Minimum Structure

“…Ever since ptC chemistry has been a subject of intensive studies 5. Numerous stable ptC‐containing molecules have been designed theoretically,6 and some global minima, such as CAl 4 − ,7 CAl 4 2− ,8 and CAl 3 Si −[9] have been detected experimentally. More interestingly, at the beginning of this century, Schleyer et al.…”

Nonorthogonal Dilithium-1,3-biborataallenes Containing Planar-Tetracoordinate Carbon Atoms

“…The central carbon atoms of all four contact‐ion triples 2 a – d ⋅2 Li⋅2 Et 2 O are surrounded by two boron atoms and two lithium ions in a planar arrangement. With Li‐C‐B angles close to 90°, they are—like Al 4 C anions11—rare examples of species in which planar‐tetracoordinate carbon atoms form angles of comparable size with all their neighbors.…”