In chemistry, a transition metal boryl complex is a molecular species with a formally anionic boron center coordinated to a transition metal. They have the formula LM-BR or LM-(BRLB) (L = ligand, R = H, organic substituent, LB = Lewis base).  One example is (CMe)Mn(CO)(BHPMe) (Me = methyl). Such compounds, especially those derived from catecholborane and the related pinacolborane, are intermediates in transition metal-catalyzed borylation reactions.