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Alkali metal hydridotriphenylborates [(L1)M][HBPh3] (L1=Me6TREN; 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 Me4TACD (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. [ABSTRACT FROM AUTHOR]