Structure and bonding in (R2SiX)2 molecules (X = O, NH, CH2, or S; R = H)

Jemmis, Eluvathingal D.; Kumar, Pavan; Kumar, Neha Rani

doi:10.1039/dt9870000271

Cited by 13 publications

(10 citation statements)

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“…If there is no σ bond, why is the Si‐Si distance not much elongated? Here comes a situation similar to what is seen in 1,3‐disila‐2,4‐dioxacyclobutane, Si 2 O 2 H 4 where short Si‐Si distance results from O‐O repulsion than Si−Si bonding [21] . The sum of atomic radii of B and N is 3.3 Å.…”

Section: Methodssupporting

confidence: 67%

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A Neutral Three‐Membered 2π Aromatic Disilaborirane and the Unique Conversion into a Four‐Membered BSi₂N‐Ring

et al. 2020

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We report the design, synthesis, structure, bonding, and reaction of a neutral 2p aromatic three-membered disilaborirane. The disilaborirane is synthesized by a facile one-pot reductive dehalogenation of amidinato-silylene chloride and dibromoarylborane with potassium graphite. Despite the tetravalent arrangement of atoms around silicon, the threemembered silicon-boron-silicon ring is aromatic, as evidenced by NMR spectroscopy, nucleus independent chemical shift calculations, first-principles electronic structure studies using density functional theory (DFT) and natural bond orbital (NBO) based bonding analysis. Trimethylsilylnitrene, generated in situ, inserts in the SiÀSi bond of disilaborirane to obtain a four-membered heterocycle 1-aza-2,3-disila-4-boretidine derivative. Both the heterocycles are fully characterized by X-ray crystallography. The synthesis of three-membered aromatic rings has been a fascinating topic for the chemical community during the last decades. Aromaticity and Hückel 4n + 2 rule continue its diversity with the smallest, largest, homo-, hetero-, Mçbius, all-carbon, organometallic-and so on, but most of these involve overlap of p, d and f orbitals. [1-3] A challenging question is it possible to generate a carbon-free neutral threemembered aromatic ring. The neutral three-membered aromatic compound with 2p electrons is one of the longest quests to inorganic, organic and theoretical chemists. [1, 4] Most of the reported small aromatic species are anionic or cationic. [4-11] Recent reports of the carbon-free aromatic systems all involve charged species: B 3 À (observed in gas phase), [6] Li 3 + (observed in gas phase), [7] [B 3 (CO) 3 ] + (observed in gas phase), [8] [B 3 (NCy 2) 3 ] 2À (characterized by X-ray), [9] [SiRSi 2 R' 2 (R = Si t Bu 3 , R' = SiMe t Bu 2)] + (characterized by X-ray), [10] [Ge 3 R 3 , R = Si t Bu 3 ] + (characterized by X-ray). [11] To develop carbon-free small neutral Hückel p systems with orbitals beyond p, d and f, unique design strategies must be assembled. Here, we present a novel approach where two of the three p orbitals are replaced by s* MOs to generate a neutral 2p aromatic three-membered disilaborirane. To synthesize carbon-free neutral three-membered 2p aromatic system, we replace one of the CH group of the classical cyclopropenyl cation by isoelectronic BR group and the remaining two CH groups by two amidinato-silylene groups to retain the 2p aromaticity, leading to the formation of a disilaborirane. [12] We envision that the extra electrons from the two amidinato-ligands will populate the stable delocalized p MO resulting from the 2p orbital of boron atom and the two s* MOs on silicon atoms in the neutral Si 2 B three-membered ring. 13 The two p electrons will conjugate in the field of the three nuclei of Si-B-Si. Accordingly, we design and synthesize the three-membered disilaborirane (Scheme 1). A 2:1:4 molar ratio of amidinato-silylene chloride [LSi-Cl; L = PhC(NtBu) 2 ], dibromo(2,4,6-triisopropylphenyl)borane and KC 8 is reacted in THF at À78 8C and...

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Section: Methodssupporting

confidence: 67%

“…Here comes a situation similar to what is seen in 1,3-disila-2,4-dioxacyclobutane, Si 2 O 2 H 4 where short Si-Si distance results from O-O repulsion than SiÀSi bonding. [21] The sum of atomic radii of B and N is 3.3 . The non-bonded B-N distance in 2 is shortened to 2.763 already.…”

Section: Angewandte Chemiementioning

confidence: 99%

A Neutral Three‐Membered 2π Aromatic Disilaborirane and the Unique Conversion into a Four‐Membered BSi₂N‐Ring

et al. 2020

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“…Molecules with Si−Si distances as short as a standard single bond without chemical bonding were earlier reported by West and co‐workers . Such a situation had theoretically been predicted by Jemmis …”

Section: Figurementioning

confidence: 59%

“…[26] Such as ituationh ad theoretically been predicted by Jemmis. [27] In summary,w eh ave presentedt he synthesis, spectroscopic identification, and quantum chemicalc alculations of the noble gas complexes NgÀBe 2 O 2 ÀNg' (Ng, Ng' = Ne,A r, Kr,X e), which possess very short BeÀBe distances withoutab ond. This is the first observation of am olecule in ac ondensed phase where the interatomic distance between two atoms is shorter than as tandard double bond without chemical bonding.…”

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confidence: 99%

A Very Short Be–Be Distance but No Bond: Synthesis and Bonding Analysis of Ng–Be₂O₂–Ng′ (Ng, Ng′=Ne, Ar, Kr, Xe)

Zhang

Zhao

et al. 2017

Chemistry A European J

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Short interatomic distances below standard values for a single bond are usually identified with double or triple bonds. The synthesis and spectroscopic characterization of a molecule is reported where the distance between two beryllium atoms is shorter than a standard double bond but there is no bond. The cyclic diberyllium dioxide Be O molecule, which is coordinated by two noble gas atoms in Ng-Be O -Ng' (Ng, Ng'=Ne, Ar, Kr, Xe) was isolated and spectroscopically identified in low-temperature matrices. The complexes possess very short Be-Be distances, but the analysis of the electronic structure reveals that there is no chemical bond.

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“…Assuming planar square geometries for (RzSiX)2 ring systems, the Si..Si distance directly depends on the Si-X bond length. If the Si-O bonds have normal lengths, the corresponding Si..Si contact necessarily has to be unusually small (Jemmis et al 1987;Masamune et al 1989;Schmidt et al 1991). A similar suggestion has been made to estimate non-bonded Si..Si distances in several ring systems (Kabe et al 1990).…”

Section: Models For Interpreting Phantom Bondsmentioning

confidence: 67%

Factors contributing to phantom bonds in inorganic molecules: Interpretations and predictions

Rathna

Chandrasekhar

1994

Proc. Indian Acad. Sci. (Chem. Sci.)

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The validity of various qualitative proposals for interpreting and predicting the existence of short contacts between formally non-bonded atoms, as in cyclodisiloxane and related inorganic ring systems, is critically evaluated. The models range from simple considerations of geometric constraints, lone pair repulsions and n-complex formation to proprsals such as the unsupported 7t-bond model and the a-bridged-~ bond concept. It is pointed out that a unified description based on a combination of closed and open 3-centre 2-electron bonds is possible. The role of hybridisation is emphasized in the short phantom bond computed in an earlier model system. These insights are used to predict structures with exceptionally short Si..Si and B..B phantom bonds. The proposals are confirmed by ab initio calculations.

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Structure and bonding in (R2SiX)2 molecules (X = O, NH, CH2, or S; R = H)

Cited by 13 publications

References 1 publication

A Neutral Three‐Membered 2π Aromatic Disilaborirane and the Unique Conversion into a Four‐Membered BSi₂N‐Ring

A Neutral Three‐Membered 2π Aromatic Disilaborirane and the Unique Conversion into a Four‐Membered BSi₂N‐Ring

A Very Short Be–Be Distance but No Bond: Synthesis and Bonding Analysis of Ng–Be₂O₂–Ng′ (Ng, Ng′=Ne, Ar, Kr, Xe)

Factors contributing to phantom bonds in inorganic molecules: Interpretations and predictions

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Structure and bonding in (R2SiX)2 molecules (X = O, NH, CH2, or S; R = H)

Cited by 13 publications

References 1 publication

A Neutral Three‐Membered 2π Aromatic Disilaborirane and the Unique Conversion into a Four‐Membered BSi2N‐Ring

A Neutral Three‐Membered 2π Aromatic Disilaborirane and the Unique Conversion into a Four‐Membered BSi2N‐Ring

A Very Short Be–Be Distance but No Bond: Synthesis and Bonding Analysis of Ng–Be2O2–Ng′ (Ng, Ng′=Ne, Ar, Kr, Xe)

Factors contributing to phantom bonds in inorganic molecules: Interpretations and predictions

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A Neutral Three‐Membered 2π Aromatic Disilaborirane and the Unique Conversion into a Four‐Membered BSi₂N‐Ring

A Neutral Three‐Membered 2π Aromatic Disilaborirane and the Unique Conversion into a Four‐Membered BSi₂N‐Ring

A Very Short Be–Be Distance but No Bond: Synthesis and Bonding Analysis of Ng–Be₂O₂–Ng′ (Ng, Ng′=Ne, Ar, Kr, Xe)