Anion isoelectronic

The planar cyclic Pj anion isoelectronic with cyclopentadienyl anion has been prepared in the form of M Pj" salts (M = Li, Na) by Handler et al. [49], The penta-phosphole anion Pj" favors planar geometry [50] while the most stable structure of P/ is square-pyramidal [51], The negatively charged pentamers Sb and Bi are planar rings [52, 53],... 

Even more puzzling are the structures of anions isoelectronic with XeF. Human spectroscopy indicates that the IF anion, like XeF. has lower symmetry than... 

The NSCh anion, isoelectronic withOSCb, is prepared by the addition of [Pl PJCl or [Me4N]Cl to a solution of (NSC1)3 in CH2CI2. The NSCb anion in the [(Ph3PN)2SCl]+ salt has a slightly distorted C structure with a very short S-N bond (144 pm) and two loosely bound chlorine atoms [d(S-Cl) = 242 pm], The structure is best described by three resonance forms (see Scheme 5). 

Proton attack on [Fe(C0)4] gives the hydride FeHjfCO) ", a light-yellow substance (m.p. - 70°C), which decomposes rapidly at RT. The [Fe(CO)4] anion, isoelectronic with Ni(CO)4, has a distorted tetrahedral structure, depending on the countercation -. ... 

In contrast to the several anionic carbonyl derivatives of iron, only one anionic cobalt carbonyl is known which does not contain other ligands. This is the tetrahedral [Co(CO)4] anion, isoelectronic with the neutral Ni(CO)4 and with the [Fe(CO)4] anion. The [Co(CO)4] ion may be obtained by a variety of methods such as the following ... 

The hydrostannation of a diyne followed by transmetallation using a borane leads to the phenylboratabenzene anion, isoelectronic to biphenyl (the prefix borata means that a benzene CH group is replaced by the isoelectronic BH group). It is equivalent to the cyclopentadienyl anion and gives transition-metal sandwich complexes that are equivalent to metallocenes with a variety of metals (V, Cr, Fe, Co, Ru, Os). - ... 

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