Reactions Of TM Complexes In Solution

Question 1

Classes of ligand substitution reactions

Answer 1

Dissociative or associative
Most lie in between = interchange (I)

Question 2

Intermediate

Answer 2

Minima on reaction profile with increasing(A)/decreasing(D) coordination number

Question 3

Interchange reactions

Answer 3

Concerted addition of Y/loss of X

Question 4

Types of interchange reactions

Answer 4

Dissociative interchange (Id) = bond breaking dominates, rate independent of Y/[Y]
Associative interchange (Ia) = bond formation dominates, rate proportional to Y/[Y]

Question 5

Square planar complexes

Answer 5

Seen for d8, evidence = A/Ia = dependence of Y/independent of charge for displacement of same ligand from different complexes

Question 6

Stereochemistry of Pt(II) substitution

Answer 6

Stereoretentive

Question 7

Trans effect

Answer 7

Trans influence = weakening of trans Pt-X bond due to competition for electron density in trans bonds
Kinetic trans effect = stabilisation of structure due to coplanar sharing of electron density

Question 8

Sequence of ability to direct trans substituents

Answer 8

H2O = OH- = NH3 = py < Cl- < Br- < I- = NO2- < Ph- < Me- < PR3 = H- &laquo_space;CO = CN-

Question 9

Nucleophility parameter, npt

Answer 9

Determined from relative rate constants of different nucleophiles with same complex
Npt = log(k2/k2’)

Question 10

Rate law for reactions with different complexes

Answer 10

Log(k2) = Snpt + log(k2’)
S = nucleophilicity discrimination factor
Smaller S = less discrimination between entering ligands