Heterolytic H-H Bond Activation

Question 1

Heterolytic H-H bond activation used for

Answer 1

ketone hydrogenation to give secondary alcohols

Question 2

catalyst used

Answer 2

ruthenium with at least one primary/secondary amine ligand, 2 phosphine ligands and a Cl

Question 3

why chiral ligands used

Answer 3

achieves high enantiometic excess

Question 4

chemoselectivity

Answer 4

hydrogenation with [Ru] catalyst only works due to CO polarity, proceeds via 6-membered TS

Question 5

stereoselectivity

Answer 5

minimise steric repulsion caused by bulky phosphine substituents

Question 6

H-H activation via s-bond metathesis requirements

Answer 6

d0 = e- deficient metal with lots of ionic character

Question 7

mechanism for H-H activation via s-bond metathesis

Answer 7

H-H approached parallel to MR bond giving polarisation of e- density, MR bond stretches, 2e- in MR bond become available, H+ transfer forms new RH bond, H- transfers to M