Isolobal analogy, extensions

The fifth of these isolobal analogy extensions is sophisticated and deserves further explanation. We will consider two examples, the parallels between (octahedral)... 

The fifth of these extensions of the isolobal analogy is less obvious than the oth- ... 

CH3 is isolobal with 17-electron ZnCrj -CsMes) (extension 4 of the analogy). 

CH2 is isolobal with 16-electron Ir(PPh3)2(CS)Cl (start with 16-electron [Ir(CO)4]+ from the parent octahedron, and substitute PPh3, Cr, and CS, respectively, for CO, extension 2 of the analogy). 

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