The correct increasing order of trans-effect of the following species is

Options

A. `d^(9)`
B. `d^(7)`
C. `d^(8)`
D. `d^(4)`

Answer

C

Explanation

Trans effect : The intensity of trans effect depend on increase in rate of substitution of the trans ligand. `F^(-) lt NH_(3) lt CI^(-) lt Br^(-) lt Ph^(-) lt CH_(3)^(-) lt CN^(-)`. Trans effect in certain ligands increase the rate of ligand substitution when positioned trans to the departing ligand.
Strong trans effect `="strong "sigma "sigma " donor + strong "pi " donor (Weak)"`
`F^(-), OH^(-), H_(2)O, NH_(3), Py lt Cl^(-) lt Br^(-) lt I^(-) lt SCN^(-) lt NO_(2)^(-)`
`Ph^(-) lt SO_(3)^(2-) lt PR_(3) lt CH_(3)^(-) lt H^(-), NO, CO, CN^(-), C_(2)H_(4)`