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In chemistry, an unpaired electron is an electron that occupies an orbital of an atom singly, rather than as part of an electron pair. Each atomic orbital of an atom (specified by the three quantum numbers n, l and m) has a capacity to contain two electrons ( electron pair ) with opposite spins .
All of the lanthanides form sesquioxides, Ln 2 O 3. The lighter (larger) lanthanides adopt a hexagonal 7-coordinate structure while the heavier/smaller ones adopt a cubic 6-coordinate "C-M 2 O 3" structure. [11] All of the sesquioxides are basic, and absorb water and carbon dioxide from air to form carbonates, hydroxides and hydroxycarbonates. [7]
Metal-carbon σ bonds are found in alkyls of the lanthanide elements such as [LnMe 6] 3− and Ln[CH(SiMe 3) 2] 3. [1] Methyllithium dissolved in THF reacts in stoichiometric ratio with LnCl 3 (Ln = Y, La) to yield Ln(CH 3) 3 probably contaminated with LiCl. Chemical structures of [LnMe6]3- and Ln[CH(SiMe3)2]3
Other than Ce(IV) and Eu(II), none of the lanthanides are stable in oxidation states other than +3 in aqueous solution. In terms of reduction potentials, the Ln 0/3+ couples are nearly the same for all lanthanides, ranging from −1.99 (for Eu) to −2.35 V (for Pr). Thus these metals are highly reducing, with reducing power similar to alkaline ...
Valence bond theory views bonds as weakly coupled orbitals (small overlap). Valence bond theory is typically easier to employ in ground state molecules. The core orbitals and electrons remain essentially unchanged during the formation of bonds. σ bond between two atoms: localization of electron density Two p-orbitals forming a π-bond.
where 1 J X-Y is the one-bond NMR spin-spin coupling constant between nuclei X and Y and χ S (α) is the s character of orbital α on carbon, expressed as a fraction of unity. As an application, the 13 C- 1 H coupling constants show that for the cycloalkanes , the amount of s character in the carbon hybrid orbital employed in the C-H bond ...
A representative example is the reaction of hydrogen with Vaska's complex, trans-IrCl(CO)[P(C 6 H 5) 3] 2. In this transformation, iridium changes its formal oxidation state from +1 to +3. The product is formally bound to three anions: one chloride and two hydride ligands. As shown below, the initial metal complex has 16 valence electrons and a ...
The rule is based on the fact that the valence orbitals in the electron configuration of transition metals consist of five (n−1)d orbitals, one ns orbital, and three np orbitals, where n is the principal quantum number. These orbitals can collectively accommodate 18 electrons as either bonding or non-bonding electron pairs.