Identifying the Hydrogenated Planar Tetracoordinate Carbon: A Combined Experimental and Theoretical Study of CAl₄H and CAl₄H^–

Abstract

The chemical curiosity “planar tetracoordinate carbon” (ptC) has greatly broadened one’s knowledge of molecular bonding motifs apart from the traditional, tetrahedral, van’t Hoff and LeBel’s concept. Synthesized ptC examples have been reported either in the solid state or in the gas phase, where the ptC core is usually metalized or organometallized. Surprisingly, there has been no experimental report on hydrogenated ptC to date. A possible answer to this situation could be the “promiscuity” of hydrogen when binding to other elements, which frustrates the formation of stable ptC that is in competition with other structures. In this Letter, we for the first time identified two hydrogenated ptC species, CAl4H and CAl4H–, based on a photoelectron spectroscopic and quantum chemical study. The favorable site-selectivity of hydrogen was shown to be the bridge of the Al–Al bond rather than the terminus of Al, manifesting the thermodynamic preference of the 17e/18e counting rule over the 15e/16e rule.

CLiAl2E and CLi2AlE (E = P, As, Sb, Bi): Planar Tetracoordinate Carbon Clusters with 16 and 14 Valence Electrons

“…3 Since then, considerable and continuous efforts have been devoted to design, prediction, and production of planar tetra-, penta-, hexa-, and heptacoordinate carbon (ptC, ppC, phC, and p7C) species 4−9 for decades, due to their unusual structures, peculiar bonding properties, and potential application prospect. Several ptC clusters including NaAl 4 C – , CAl 3 Si – , CAl 3 Ge – , and CAl 4 H – have been observed in the gas photoelectron spectroscopy (PES) experiments, 10−12 which are isoelectronic with previously reported cis -CSi 2 Al 2 and trans -CSi 2 Al 2 by Schleyer and Boldyrev.…”

Global Isomeric Survey of Elusive Cyclopropanetrione: Unknown but Viable Isomers

“…The connection of each transition state was determined by the intrinsic reaction coordinate (IRC) (Fukui, 1981) calculations. The effectiveness of such isomeric and TS search strategies has been confirmed in study of various small to medium-sized systems (Cui et al, 2011; Gao and Ding, 2012; Tang et al, 2012; Guo et al, 2013a,b, 2014; Zhang and Ding, 2014, 2015; He and Ding, 2016; Xu et al, 2017; Bo et al, 2019).…”

Stabilization of beryllium-containing planar pentacoordinate carbon species through attaching hydrogen atoms

“…CAl 4 H and CAl 4 H À . 16 For ppC species, the most studied seed structure should be CBe 5 4À , 8 which is even not an eligible minimum. 17 Nevertheless, through attaching the auxiliary atoms, like alkali metals, hydrogen, halogens, and even transition metal gold, a family of ppC species can be designed, including CBe 5 Li n nÀ4 (n ¼ 1-5), 17a CBe 5 H n nÀ4 (n ¼ 2, 3, 5), 17b…”