Total electron count, calculation

Number of electrons in ferrocene 1 can be counted in the following way. In ferrocene, Fe is Fe(II) and has six d-electrons. The cyclopentadienyl anion donates six electrons (2x2 from two double bonds and two electrons from the anion), and 6 + (4 x 2) + (2 x 2) = 18 electrons satisfy the rule. In another calculation Fe, regarded as Fe(0), offers eight electrons and the cycloptendienyl radical supplies one electron. Therefore, total electron count is 8 + (4 x 2) + (1 x 2) = 18. 

Another method for determining total electron count treats odd-electron donor ligands (alkyl, Cp, etc.) as anionic, even-electron donors. The number of electrons contributed by the metal is calculated from the metal s oxidation state. Both methods give the same answer for total electron count. 

The deprotonation of M-H to give M and H+ is one quite common dissociation reaction in which the pair of electrons of the bond goes to the metal. The metal doesn t change its total electron count, and its oxidation state decreases by 2. It s strange to think of a deprotonation as causing a reduction of the metal. The conundrum arises because of the oddities of the language that is used to describe metal complexes. The oxidation state of a complex with a M-H bond is calculated as if the bond were polarized toward H (i.e., M+ 11 ). Thus, when metal hydrides are deprotonated, it seems as if the metal is gaining electrons (from the hydride) that it did not have previously. 

The structure of MnP is a distorted variant of the NiAs type the metal atoms also have close contacts with each other in zigzag lines parallel to the a-b plane, which amounts to a total of four close metal atoms (Fig. 17.5). Simultaneously, the P atoms have moved up to a zigzag line this can be interpreted as a (P-) chain in the same manner as in Zintl phases. In NiP the distortion is different, allowing for the presence of P2 pairs (P ). These distortions are to be taken as Peierls distortions. Calculations of the electronic band structures can be summarized in short 9-10 valence electrons per metal atom favor the NiAs structure, 11-14 the MnP structure, and more than 14 the NiP structure (phosphorus contributes 5 valence electrons per metal atom) this is valid for phosphides. Arsenides and especially antimonides prefer the NiAs structure also for the larger electron counts. 

The ratio of total radioactivity between the growing and quiescent areas as estimated by scintillation counting (or electron flux calculated in part from counts per minute) was approximately 1.8 at 5 minutes, 2.3 at 1 hour, and 2.9 at 24 hours. 

The above calculation suggests that a singlet formation due to strong correlations with a triplet excited state should be found in appropriate molecules. The effect requires an even total number of valence electrons. In order to detect it one should search e.g. for molecules containing Ce, which are diamagnetic, but which show a f-electron count close to 1, when photoemission experiments are performed. 

Lauher, subsequently, performed Extended Hiickel calculations on a wide range of n-atom closo transition metal clusters and confirmed the presence of (2n - 1) high-lying inaccessible antibonding orbitals, leaving a total of (9n - (2n - 1) = (7n + 1) occupied cluster valence MO s and an electron count of (14 n + 2)85. Lauher s calculations were made on bare metal clusters and the introduction of ligands was considered to constitute only a small perturbation. Calculations on nido and arachno transition metal clusters showed them to be characterised by (14 n + 4) and (14 n + 6) valence electrons... 

Note that the total electron energy is not identical to the sum of the two orbital energies, because the latter doubly counts the electron-electron interactions. The total energy is calculated by adding the nucleus-nucleus repulsion energies to the total electron energy. 

The predictions of the improved model match the results obtained from ab initio calculation of the induced current density for the HC = CH-clamped benzene [22] and COT [23] (see Fig. 2a and 2b). The original benzene (1) diatropic ring current and the COT (2) paratropic current are completely quenched when HC = CH clamps are applied. Despite the formally antiaromatic TT-electron count of both clamped molecules, global paratropic current is not observed, the total r-current consisting of a set of diatropic vortices localised over the short bonds. 

The oxidation state of the metal is calculated as total charge over the complex minus charges over the ligands. The number of electrons contributed by metal is calculated as the group number minus its oxidation number. Finally, the electron count is completed as the total of electrons on the metal and the electrons contributed by the Ugands. 

One of the unique features of PEPICO is the ability to determine the collection efficiencies and thus the absolute total ionization rate, The ion and electron collection efficiencies (E- and E ) can be calculated from the coincidence count rates (N ) and the observed ion and electron count rates (N- and N ). They are given by... 

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