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The possible products include SiH 4 and/or higher molecules in the homologous series Si n H 2n+2, a polymeric silicon hydride, or a silicic acid. Hence, M II Si with their zigzag chains of Si 2− anions (containing two lone pairs of electrons on each Si anion that can accept protons) yield the polymeric hydride (SiH 2) x.
Although monosilane and disilane were already known, Stock and Somiesky discovered, beginning in 1916, the next four members of the Si n H 2n+2 series, up to n = 6. They also documented the formation of solid phase polymeric silicon hydrides. [3] One of their synthesis methods involved the hydrolysis of metal silicides.
[1] [2] It is also known as the Pimentel–Rundle three-center model after the work published by George C. Pimentel in 1951, [3] which built on concepts developed earlier by Robert E. Rundle for electron-deficient bonding. [4] [5] An extended version of this model is used to describe the whole class of hypervalent molecules such as phosphorus ...
Another example is O(SiH 3) 2 with an Si–O–Si angle of 144.1°, which compares to the angles in Cl 2 O (110.9°), (CH 3) 2 O (111.7°), and N(CH 3) 3 (110.9°). [24] Gillespie and Robinson rationalize the Si–O–Si bond angle based on the observed ability of a ligand's lone pair to most greatly repel other electron pairs when the ligand ...
Gilbert N. Lewis introduced the concepts of both the electron pair and the covalent bond in a landmark paper he published in 1916. [1] [2] MO diagrams depicting covalent (left) and polar covalent (right) bonding in a diatomic molecule. In both cases a bond is created by the formation of an electron pair.
This would result in the geometry of a regular tetrahedron with each bond angle equal to arccos(− 1 / 3 ) ≈ 109.5°. However, the three hydrogen atoms are repelled by the electron lone pair in a way that the geometry is distorted to a trigonal pyramid (regular 3-sided pyramid) with bond angles of 107°.
The geometry is prevalent for transition metal complexes with d 8 configuration, which includes Rh(I), Ir(I), Pd(II), Pt(II), and Au(III). Notable examples include the anticancer drugs cisplatin, [PtCl 2 (NH 3) 2], and carboplatin. Many homogeneous catalysts are square planar in their resting state, such as Wilkinson's catalyst and Crabtree's ...
6/n "[AlBr] n" → Al 2 Br 6 + 4 Al. This reaction is reversed at temperatures higher than 1000 °C. Aluminium monobromide has been crystallographically characterized in the form the tetrameric adduct Al 4 Br 4 (NEt 3) 4 (Et = C 2 H 5). This species is electronically related to cyclobutane.