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The 18-electron rule is a chemical rule of thumb used primarily for predicting and rationalizing formulas for stable transition metal complexes, especially organometallic compounds. [1] 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 n s orbital ...
Tolman's rule states that, in a certain chemical reaction, the steps involve exclusively intermediates of 18- and 16 electron configuration. The rule is an extension of the 18-electron rule . This rule was proposed by American chemist Chadwick A. Tolman . [ 1 ]
Quantum chemical calculations using density functional theory confirm that Ca, Sr, and Ba can indeed utilize their (n-1)d in bonding to satisfy the 18-electron rule. [1] [6] These computational results support the hypothesis that alkaline earth octacarbonyl complexes follow the 18-electron rule and are comparable to carbonyl transition metal ...
From the perspective of the 18-electron rule, the four ligands each provides two electrons, for a total of 16-electrons. As such the compound is coordinatively unsaturated , i.e. susceptible to binding substrates (alkenes and H 2 ).
In organometallic chemistry, (η 6-C 6 H 6) piano stool compounds are half-sandwich compounds with (η 6-C 6 H 6)ML 3 structure (M = Cr, Mo, W, Mn(I), Re(I) and L = typically CO). (η 6-C 6 H 6) piano stool complexes are stable 18-electron coordination compounds with a variety of chemical and material applications.
In 1972, he proposed the 16 and 18 electron rule, extending Irving Langmuir's 18-Electron rule to include the many examples of stable 16 electron square planar d 8 complexes. [4] Later work focused on the activation of C-H bonds by transition metal complexes [ 5 ] [ 6 ] and free radical oxidation of cyclohexane for the production of adipic acid ...
The 18-electron rule is the equivalent of the octet rule in main group chemistry and provides a useful guide for predicting the stability of organometallic compounds. [34] It predicts that organometallic species "in which the sum of the metal valence electrons plus the electrons donated by the ligand groups total 18 are likely to be stable."
The Fe-NO bonds are linear indicating NO is acting as a three electron donor. [3] The diamagnetic compound obeys the 18-electron rule . The dark red colour of the complex is attributed to a number of charge-transfer interactions between the iron core and nitrosyl ligands.