Substitution In Octahedral Complexes

Question 1

Eigen-Wilkins Mechanism

Answer 1

see notes
ML6 + Y -> {ML6,Y} = weakly associated complex -> products
Overall rate = k2[{ML6,Y}]
Do rapid pre-equilibrium of {ML6,Y}

Question 2

Associative of dissociative?

Answer 2

K2 varies little with nature of Y so Id

Question 3

Evidence of Eigen-Wilkins/Id

Answer 3

At low [Y] =second order
At high [Y] = first order
Dependence on leaving group = weaker M-X bond = more labile and k proportional to 1/MX bond energy