Compounds containing a planar-tetracoordinate carbon atom as analogues of planar methane

Abstract

Over the past years the number of examples of compounds containing a planar-tetracoordinate carbon atom has increased. However, the presence of a carbon atom with a 360°s um of angles does not imply that the species is a derivative of planar methane; there must be an appropriate electronic stabilization. In the case of complexes 21a and 21b the central carbon atom is indeed stabilized by s-donors and pacceptors, as required for planar methane.

Recent advances in planar tetracoordinate carbon chemistry

“…Inspired on Hoffmann's ideas, several groups have successfully suggested and experimentally characterized molecules containing ptCs. [12][13][14][15][16][17] It is not pretentious to say that the works around ptCs opened a new age of carbon chemistry.…”

Extending the Chemistry of [5.5.5.5]Fenestranes − Eightfold Peripheral Functionalization of Fenestrindanes

“…This motif is now of interest not only in organic but also in metalorganic [4] and inorganic chemistry, [5] and inspiration from theoretical chemistry may lead to further developments in the organic chemistry of flattened or planar tetracoordinate carbon. [6] However, the synthetic utility of fenestranes as building blocks in organic chemistry has not been exploited to any great extent, [7] and only the facile access to benzoannelated derivatives of [5.5.5.5]-and [5.5.5.6]fenestranes has opened promising routes to extended molecular frameworks bearing the three-dimensional fenestrane core.…”

“…Ϫ MS (DEI, 70 eV); m/z (%): 1129 (67) [M ϩ· ], 1114(24), 1074(33), 1059(12), 1020 (10), 986(7), 971(5), 564(8) [M 2ϩ ], 537 (3), 56 (100). Ϫ HRMS: calcd.…”

Stabilization of octacoordinate carbon center in metal-containing derivatives of orthocarbonic acid

“…In this respect, the best developed field is hypercarbon chemistry for which not only a vari ety of non classical hypercarbon compounds have been found but also efficient methods for the design and stabi lization of such systems were developed. [1][2][3][4][5][6][7][8][9] One of the most convenient and promising approaches to the design of systems with hypercoordinate centers is based on the "induced aromaticity" effect. 10 This meth odology involves the incorporation of counterions (usu ally, lithium cations) into originally unstable anionic non classical systems.…”