A New Approach to the Design of Neutral 10‐C‐5 Trigonal‐Bipyramidal Carbon Compounds: A “π‐Electron Cap” Effect

Abstract

DFT (B3LYP, M06-2X) and MP2 methods are applied to the design of a wide series of the potentially 10-C-5 neutral compounds based on 6-azabicyclotetradecanes: XC(1)(YCH2CH2CH2)3N 1-3, XC(1)(YC6H4CH2)3N 4-6, XC(1)[Y(tBuC6 H3)CH2]3N 7-9 and carbatranophanes C6H3[XC(1)(YC6H3CH2)3N] 10-25 (X = Me, F, Cl; Y = O, NH, CH2, SiH2; Z = O, CH2, (CH2)2, (CH2)3). Carbatranophanes 10-25 are characterized by a sterical compression of their axial 3c-4e XC(1)←N fragment with respect to that in the parent molecules 4-6. A magnitude of the revealed effect depends on a valence surrounding of the central carbon atom C(1), the size and the nature of the side chains (Z) that link the "π-electron cap" with a tetradecane backbone. This circumstance allowed us to obtain 10-C-5 structures with the configuration of the bonds around the C(1) atom, which corresponds to practically an ideal trigonal bipyramid. In these compounds, the values of the covalence ratio χ (C1←N) of approximately 0.6 for the coordination C(1)←N contacts with a covalent contribution (atoms in molecules (AIM) and natural bond orbital (NBO)) are record in magnitude. These values lie close to a low limit of the interval of the χ(Si←D) change (0.6-0.9) being characteristic of the dative and ionic-covalent (by nature) Si←D bond (D = N, O) in the known 10-Si-5 silicon compounds.

Theoretical study of the geometrical, energetic and NMR properties of atranes

“…Phukan and Guha theoretically studied the nature of the where the attractive C ) N interactions are weak; however, putting a cap over the X atom (a benzene ring: carbatranophanes) they obtained structures with an almost ideal trigonal bipyramid (<XeCeO ¼ 90 , < OeCeO ¼ 120 ) [28].…”

Electrochemical Oxidation and Radical Cations of Structurally Non‐rigid Hypervalent Silatranes: Theoretical and Experimental Studies

“…All remaining calculations were carried out with Gaussian 09 [52] program package. The AIM [53] (Atoms In Molecules) estimation of the energy [54] of the N!Si dative contact (E SiN )w as carried out using the well-approved [55] relationship: E SiN = ÀV(r c )/2;w here V(r c )i st he potential energy density at the bond critical point, bcp(SiN). For this estimation we used the MP2(full)/6-311 ++G(d,p) electron distribution 1(r)o fm olecules XSi(OCH 2 CH 2 ) 3 No btained with the MORPHY 1.0 [56] program.…”

Assignment of photoelectron spectra of silatranes: first ionization energies and the nature of the dative Si←N contact

“…50,51 program was involved. The AIM estimation of the energy 52 of the dative Si'N contact (E SiN ) was performed using the well-approved 12,[53][54][55] relationship: E SiN = ÀV(r c )/2; where V(r c ) is the potential energy density in the bond critical point, bcp (SiN).…”