Isolable Analogy

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* Isolable Analogy :-

Main group elements follow = 8 electron rule
Transition element follow =18 electron rule 
        
main group element.          Transition element

        8                                                      18

        7.                                                     17

        6                                                      16

        5                                                      15

        4                                                      14

eg.Fe(CO)5=8+2x5=18
      CH4  = 4+4  = 8...........both are isolobal..

eg. Mn(CO)5 is isolobal with CH3.

eg.B6H8 is isolobal with [Os(CO)8]2-
     (B6H8),                          [Os6(CO)18]2-
    (B6H6)2- = Closo          TEC=48+36+2=86
                                             PEC=86-722=14
                                              14/2=6= 6+1=7=closo

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