Abstract:It's plain to see: A monomeric dilithio methandiide features a distorted trans‐planar four‐coordinate carbon atom. The nature of this compound as established by an X‐ray diffraction study (see picture: C black, N blue, P magenta, Li red) and supported by calculations.
“…[173] Cblack, Pblue, Ni ght blue, Li red, (Reprinted with permission from Ref. [173] [179] and Al 4 Oin1991. [180] ptO in ab ulk solid structure was predicted in 2008.…”
Section: Experimental Realization Of Planar Motifsmentioning
The idea of planar tetracoordinate carbon (ptC) was considered implausible for a hundred years after 1874. Examples of ptC were then predicted computationally and realized experimentally. Both electronic and mechanical (e.g., small rings and cages) effects stabilize these unusual bonding arrangements. Concepts based on the bonding motifs of planar methane and the planar methane dication can be extended to give planar hypercoordinate structures of other chemical elements. Numerous planar configurations of various central atoms (main-group and transition-metal elements) with coordination numbers up to ten are discussed herein. The evolution of such planar configurations from small molecules to clusters, to nanospecies and to bulk solids is delineated. Some experimentally fabricated planar materials have been shown to possess unusual electrical and magnetic properties. A fundamental understanding of planar hypercoordinate chemistry and its potential will help guide its future development.
“…[173] Cblack, Pblue, Ni ght blue, Li red, (Reprinted with permission from Ref. [173] [179] and Al 4 Oin1991. [180] ptO in ab ulk solid structure was predicted in 2008.…”
Section: Experimental Realization Of Planar Motifsmentioning
The idea of planar tetracoordinate carbon (ptC) was considered implausible for a hundred years after 1874. Examples of ptC were then predicted computationally and realized experimentally. Both electronic and mechanical (e.g., small rings and cages) effects stabilize these unusual bonding arrangements. Concepts based on the bonding motifs of planar methane and the planar methane dication can be extended to give planar hypercoordinate structures of other chemical elements. Numerous planar configurations of various central atoms (main-group and transition-metal elements) with coordination numbers up to ten are discussed herein. The evolution of such planar configurations from small molecules to clusters, to nanospecies and to bulk solids is delineated. Some experimentally fabricated planar materials have been shown to possess unusual electrical and magnetic properties. A fundamental understanding of planar hypercoordinate chemistry and its potential will help guide its future development.
“…[12] The 1 H NMR spectrum of 5 spans the range d =+ 0.4 to + 7.5 ppm and exhibits eight sharp resonances consistent with C s symmetry on the NMR timescale. The carbene center, located definitively by a 13 C-31 P 2D NMR correlation experiment, appears in the 13 C NMR spectrum as a triplet at d = 324.6 ppm (J PC = 148.7 Hz). The carbene nature is thus confirmed by this downfield chemical shift, which is well within the 200-400 ppm range of covalent transition-metal carbenes [14] and at much higher frequency than ionic yttrium-(III) analogues (d = 10-40 ppm).…”
mentioning
confidence: 99%
“…We began [12] [12,13] With 4 in hand, we reasoned that the electron-rich "ate" formulation would promote straightforward removal of the 4f-electron, thereby avoiding the unpredictable sidereactions of neutral cerium(III)-compound oxidations. [8] Treatment of 4 with one equivalent of AgBPh 4 resulted in elimination of Ag 0 and KBPh 4 to give, after work-up and recrystallization, dark purple crystals of the cerium(IV) carbene bis(aryloxide) [Ce(BIPM TMS )(ODipp) 2 ] (5, 28% yield).…”
Straightforward access to a cerium(IV)-carbene complex was provided by one-electron oxidation of an anionic "ate" cerium(III)-carbene precursor, thereby avoiding decomposition reactions that plague oxidations of neutral cerium(III) compounds. The cerium(IV)-carbene complex is the first lanthanide(IV)-element multiple bond and involves a twofold bonding interaction of two electron pairs between cerium and carbon.
“…This contrasts with the reactivity of the anion Sm[C(Ph 2 P S) 2 ] 2 − which already at room temperature gave full metathesis to Ph 2 C C(Ph 2 P S) 2 and samarium oxide [59]. Reaction of 29 with adamantylcyanide (which possesses a more accessible two-coordinate C center) only led to isolation of an adduct (37). Due to the much smaller spatial demand of the needle-like cyanide, two substrate molecules can coordinate to the dimer.…”
Section: Reactivity Of Alkaline-earth Metal Carbene Complexesmentioning
confidence: 90%
“…Very recently, however, the first monomeric structure has been reported [37]. This unusual complex was obtained by use of a bulky imino-substituent (DIPP) and a chelating co-solvent (TMEDA = N,N,N ,Ntetramethylethylenediamine), both factors which disfavour the dimerization reaction.…”
Section: A Monomeric Dilithio Bis(iminiphosphorane)methandiide Complexmentioning
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