Isoelectronic species

You will meet all the following isoelectronic species in this text. Repeat the previous problem for these three structures. 

Isoelectronic Species in the Organophosphorus, Organosilicon, and Organoaluminum Series, 9, 259... 

C08-0117. Write the ground-state configurations for the isoelectronic species, La , and Ba. Are they the same What features of orbitai energies account for this ... 

Some attention is to be paid to the isoelectronic species too, the series PO ,... 

There are several important chemical species that consist of four atoms and have a total of 24 valence-shell electrons. Some of the most common isoelectronic species of this type are C032-, N03 , S03, and P() j (known as the metaphosphate ion). Because four atoms would require a total of 32 electrons for each to have an octet, we conclude that eight electrons must be shared in four bonds. With four bonds to the central atom, there can be no unshared pairs on that atom if the octet rule is to be obeyed. Therefore, we can draw the structure for CO, 2 showing one double C=0 bond and two single C-O bonds as... 

A. Reactions of Metal Atoms with H O and Isoelectronic Species... 

Isoelectronic species must have the same number of electrons, and each element has a different atomic number, atoms of different elements cannot be isoelectronic. Two different cations may be isoelectronic, as may two different anions, or an anion and a cation. An example would be two anions (or two cations, or an anion and a cation) that have the electron configuration of a nearby noble gas, such as 02 and F", Na+ and Mg2+, or F and Na+. 

Phosphonioacetylides, which can be formally described by the limit mesomeric structures M-0 (Fig. 13), are isoelectronic species with the well-known and widely employed isocyanide ligands [71]. However, in contrast to isocyanides, they are thermally unstable, e.g., triphenylphosphonioacetylide Ph3P C=C , generated by desilylation of [R3PC=CSiMe3][OTf] with [PhCH2NMe3] [F] at -90 °C, readily decomposes at temperatures above —40 °C [71]. 

In particular, iminoboranes (XBNR) are isoelectronic with alkynes (XCCR). Well-known comparable pairs of isoelectronic species are aminoboranes (X2BNR2) and alkenes (X2CCR2), amine-boranes (X3BNR3) and alkanes (X3CCR3), borazines [(XBNR)3] and benzenes [(XCCR)3], etc. The structure of aminoboranes, amine-boranes, and borazines is well known from many examples. It has turned out that these BN species are not only isoelectronic, but also have structures comparable with the corresponding CC species. In the case of borazines, the aromatic character was widely discussed on the basis of theoretical and experimental arguments. The structural and physical properties of... 

The polyhedra in Fig. 1 thus represent suitable shapes for cluster species with n skeletal atoms (each of which can furnish three AO s for use in skeletal bonding) and with (n + 1) skeletal bond pairs. Since it is the cluster symmetry that determines the number of bonding MO s, the same polyhedra can serve as the basis for the structures of a whole range of isoelectronic species, including neutral carboranes of formula C2B 2Hn, bismuth clusters, such as the trigonal-bipyramidal Bis " ",... 

TABLE 9. Isoelectronic species with 16 valence electrons ... 

The corrections are then made by supposing that for isoelectronic species (NaF — Ne for example) the repulsion coefficients B are simply in the ratio of the nearest-neighbour co-ordination number (6 for alkali halides, 12 for inert gases). The calculation is essentially that of Pauling (7). 

As a result of this electron-filling scheme for jellium clusters, the magic numbers for closed shell configurations in a jellium cluster are very different from those in free atoms. The first magic number of chemical significance in a jellium sphere is the 20 valence electron configuration of white phosphorus P4 and other isoelectronic species of the type E4 (E = As, Sb, Bi) and E4" (E = Si, Ge, Sn, Pb), which are shown by the NICS method to be highly aromatic systems [39, 79]. 

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