SEARCH Articles Figures Tables M - B distances for r 2 - BH4 second-row transition metal complexes. In grey, complexes with one r 2-BH4 , in black, complexes with two r 2 -BH4 and in black with white lines, complexes combining x 2 and r 3 ligands. Squared bands show the average values of a data group [Publishers Imprint]