Oxidative addition is the main route to metal boryl complexes.  Both B-H and B-B bonds add to low-valent metal complexes. For example, catecholborane oxidatively adds to Pt(0) to give the boryl hydride.
:CHOBH  +  Pt(PR) →  CHOB Pt(PR)H
Addition of diboron tetrafluoride to Vaska's complex gives the triboryl iridium(III) derivative:
:2BF  +  IrCl(CO)(PPh) →   Ir(BF)(CO)(PPh)  +  ClBF