Novel transition metal complexes and use thereof in organic light-emitting diodes v

A metal complex, comprising a ligand of formula (I):

• wherein:
• Y5 is CD, CR1, CH, or N;
• D is deuterium;
• X1 is N
• X2, X3, Y1, Y2, and Y3 are each independently N or C;
• X4 is CD, CR1, CH, N, NR1, S or O;
• X5 is CD,
• Y4 and Y6 are each independently CD, CR1, CH, N, NR1, S, or O;
• Z1, Z2, and Z3 are each independently CD, CR1, CH, N, S, O, or NR1;
• R1 is independently an unsubstituted or substituted alkyl, unsubstituted or substituted cycloalkyl, unsubstituted or substituted heterocycloalkyl, unsubstituted or substituted aryl, unsubstituted or substituted heteroaryl, unsubstituted or substituted alkenyl, unsubstituted or substituted cycloalkenyl, unsubstituted or substituted alkynyl, SiR23, halogen, a substituent with donor or acceptor action, whereby, in the case that R1 is bonded to a nitrogen atom, R1 is independently an unsubstituted or substituted alkyl, unsubstituted or substituted aryl, or unsubstituted or substituted heteroaryl, whereby any two R1 radicals together may additionally form an alkylene or arylene bridge;
• R2 is independently an unsubstituted or substituted alkyl, unsubstituted or substituted aryl, or unsubstituted or substituted heteroaryl;
• m is 1;
• n is 0;
• Z4 and is absent;
• and
• the metal complex comprises a deuterium atom.