Intramolecular Hypervalent Interaction in the Conjugate Five-Membered Rings

The intramolecular hypervalent interaction between the electron abundant atomic centers X and Y belonging to the IV–VI groups and second and fourth periods has been computationally studied on a model quasi-cyclic conjugate five-membered ring system <b>9</b> using the CCSD/6-311+G** and DFT B3LYP/6-311+G** methods. Electronic and structural factors affecting the strength and geometrical characteristics of the hypervalent X←Y interaction were analyzed based on the quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses. The donor–acceptor <i>n</i>_Y→σ*_XR interaction has been shown to be the central factor correlating all important properties of the studied hypervalently bonded compounds <b>9</b>

Group 14 element cationic pentagonal–pyramidal complexes E^a[<i>η</i>⁵-E^b₅(SiMe₃)₅]⁺ (E^a = Si–Pb, E^b = Si, Ge): A quantum-chemical study

<p>Heavy 14 group element cationic half-sandwich complexes E^a[η⁵-E^b₅(SiMe₃)₅]⁺ (E^a = Si–Pb, E^b = Si, Ge) have been studied at the B3LYP/Def2TZVP level of theory. Structures of the neutral complexes {Si[Si₅(SiMe₃)₅]}⁺Cl⁻ and {Si[Si₅(SiMe₃)₅]}⁺[AlCl₄]⁻ are also discussed.</p

Supertetrahedral Aluminum – A New Allotropic Ultralight Crystalline Form of Aluminum

A new metastable ultralight crystalline form of aluminum has been computationally designed using density functional calculations with imposing periodic boundary conditions. The geometric and electronic structures of the predicted new allotrope were calculated on the basis of a diamond lattice in which all carbon atoms are replaced by aluminum Al₄ tetrahedra. The new form of crystalline aluminum has an extremely low density of 0.61 g/cm³ and would float in water. The new aluminum form is a semimetal and shows high plasticity

From Borapyramidane to Borole Dianion

Nonclassical pyramidanes with their inverted tetrahedral configuration of the apical atom are among the most challenging synthetic targets in cluster chemistry. In this Communication, we report on the synthesis and structure of the first representative of pyramidal compounds with the group 13 element at the apex, namely, chloroborapyramidane <b>2</b>. Reduction of <b>2</b> with excess of lithium metal unexpectedly produced the cage-opening product, borole dianion derivative <b>{3</b>^<b>2–</b><b>·[Li­(thf)</b>^<b>+</b><b>]</b>_<b>2</b><b>}</b>, a 6π-electron aromatic system

From Borapyramidane to Borole Dianion

Nonclassical pyramidanes with their inverted tetrahedral configuration of the apical atom are among the most challenging synthetic targets in cluster chemistry. In this Communication, we report on the synthesis and structure of the first representative of pyramidal compounds with the group 13 element at the apex, namely, chloroborapyramidane <b>2</b>. Reduction of <b>2</b> with excess of lithium metal unexpectedly produced the cage-opening product, borole dianion derivative <b>{3</b>^<b>2–</b><b>·[Li­(thf)</b>^<b>+</b><b>]</b>_<b>2</b><b>}</b>, a 6π-electron aromatic system

From Borapyramidane to Borole Dianion

Nonclassical pyramidanes with their inverted tetrahedral configuration of the apical atom are among the most challenging synthetic targets in cluster chemistry. In this Communication, we report on the synthesis and structure of the first representative of pyramidal compounds with the group 13 element at the apex, namely, chloroborapyramidane <b>2</b>. Reduction of <b>2</b> with excess of lithium metal unexpectedly produced the cage-opening product, borole dianion derivative <b>{3</b>^<b>2–</b><b>·[Li­(thf)</b>^<b>+</b><b>]</b>_<b>2</b><b>}</b>, a 6π-electron aromatic system

From Borapyramidane to Borole Dianion

Nonclassical pyramidanes with their inverted tetrahedral configuration of the apical atom are among the most challenging synthetic targets in cluster chemistry. In this Communication, we report on the synthesis and structure of the first representative of pyramidal compounds with the group 13 element at the apex, namely, chloroborapyramidane <b>2</b>. Reduction of <b>2</b> with excess of lithium metal unexpectedly produced the cage-opening product, borole dianion derivative <b>{3</b>^<b>2–</b><b>·[Li­(thf)</b>^<b>+</b><b>]</b>_<b>2</b><b>}</b>, a 6π-electron aromatic system

Bis(stibahousene)

Strained hydrocarbons constitute one of the most prominent classes of organic compounds. Among them, bicyclo[2.1.0]­pentene (“housene”) derivatives represent a highly challenging and very attractive class. Although organic housenes have been known for more than five decades, there are still very few of them containing heavier main group elements. In this paper, we report on the two housene-type structures, novel monomeric stibahousene and dimeric bis­(stibahousene). The bonding natures of both compounds were approached from both experimental and computational directions to reveal their peculiar structural features

Pyramidanes: The Covalent Form of the Ionic Compounds

Pyramidane and its derivatives are among the most desirable synthetic chemistry targets, whose appealing square-pyramidal design, fascinating nonclassical structure, and unusual bonding features have attracted the permanently growing interest of organic chemists for decades. Although they have been comprehensively approached on theoretical grounds, no member of the pyramidane family was experimentally realized until very recently, thus remaining one of the biggest synthetic challenges for experimental pursuits. In this paper, we report on a series of stable hybrid pyramidanes of group 14 elements, featuring germanium, tin, or lead at the apex of the square pyramid, capping the four-membered-ring base made of carbon, silicon, or germanium atoms. On the basis of the experimental results (X-ray diffraction and NMR and Mössbauer spectroscopy) and computational studies at the B3LYP/Def2TZVP level of theory (MO, NBO, NRT, and AIM), an extraordinarily high degree of ionicity of the pyramidal apex-to-base bonds was attributed to the overall structure of these nonclassical covalent compounds