Ligand Influence on Carbonyl Hydroboration Catalysis by Alkali Metal Hydridotriphenylborates [(L)M][HBPh3 ] (M=Li, Na, K).

Alkali metal hydridotriphenylborates [(L1 )M][HBPh3 ] (L1 =Me6 TREN; M=Li, Na, K) chemoselectively catalyze the hydroboration of carbonyls and CO2 , with lithium being the most active system. A new series of complexes [(L2 )M][HBPh3 ] [M=Li (1), Na (2), K (3)] featuring the cyclen-derived macrocyclic polyamine Me4 TACD (L2 ) were synthesized in a "one-pot" fashion and fully characterized including X-ray crystallography. In the crystal, 1-3 exhibit wide variation in metal coordination of the [HBPh3 ]- anion from lithium to potassium. The structures differ from those in [(L1 )M][HBPh3 ]. Effects of coordination of L1 , L2 , and other N- and O-donor multidentate ligands on [Li(HBPh3 )] were used to rationalize the catalytic activity in carbonyl hydroboration.