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

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

Pyramidanes

Pyramidane is an elusive but highly desirable target for synthetic chemists that has attracted a great deal of attention because of its nonclassical structure and unusual bonding features. Although well studied on theoretical grounds, neither the parent all-carbon pyramidane nor its derivatives containing heavier group 14 elements have ever been isolated and characterized. In this Communication, we report on the synthesis and structural elucidation of the first stable representatives of this class of highly strained polyhedral compounds: germa- and stannapyramidanes Ge[C₄(SiMe₃)₄] and Sn­[C₄(SiMe₃)₄]. The peculiar structural and bonding features of these compounds are verified by combined experimental and computational analyses, showing these derivatives to be nonclassical neutral compounds with a very large contribution of ionic character

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

Pyramidanes

Pyramidane is an elusive but highly desirable target for synthetic chemists that has attracted a great deal of attention because of its nonclassical structure and unusual bonding features. Although well studied on theoretical grounds, neither the parent all-carbon pyramidane nor its derivatives containing heavier group 14 elements have ever been isolated and characterized. In this Communication, we report on the synthesis and structural elucidation of the first stable representatives of this class of highly strained polyhedral compounds: germa- and stannapyramidanes Ge[C₄(SiMe₃)₄] and Sn­[C₄(SiMe₃)₄]. The peculiar structural and bonding features of these compounds are verified by combined experimental and computational analyses, showing these derivatives to be nonclassical neutral compounds with a very large contribution of ionic character

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