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The Theoretical Design of Neutral Planar Tetracoordinate Carbon Molecules with C(C)4 Substructures

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journal contribution
posted on 11.09.2002, 00:00 authored by Zhi-Xiang Wang, Paul von Ragué Schleyer
Using a new charge-compensation strategy, we designed neutral molecules with perfectly planar C(C)4-type tetracoordinate carbon arrangements (ptC) employing DFT computations. These designs, based on the planar preference of methane dications, replace two remote carbons in spiroalkaplanes by borons or two remote hydrogens by BH3 groups; the two formally anionic boron units which result compensate the formal double positive charge on the central ptC's. The LUMOs correspond to the “wasted” lone pair HOMOs of the alkaplanes. As compared to the latter, π occupancies on the central carbon are much smaller (less than 0.7e), and the IPs are much larger. The newly predicted compounds utilize all of the electrons more effectively. There are no lone pairs, and the ptC−C bond lengths are ca. 1.50 Å. The Wiberg bond index sums of the ptC's are near 3.2, and the boron sums are close to 4.