Organic electroluminescent materials and devices

A compound of

• wherein:
• M is Pd or Pt;
• Z1-Z2 are each independently C or N with one being N and the other C;
• Z3-Z4 are each independently C or N with one being N and the other C;
• X is C or N;
• each of X1—X6, and X12—X13 is independently C or N;
• at least two of adjacent X1—X4 are C, and are fused to a structure of
• each of K1, K2, K3, and K4 is independently a direct bond, O, or S, with at least two of K1, K2, K3, and K4 being direct bonds;
• Y is selected from the group consisting of O, S, Se, BR, NR, CRR′, and SiRR′;
• L is absent, a direct bond, or a linker selected from the group consisting of
• and combinations thereof;
• L1 is selected from the group consisting of O, S, NR, CRR′, and SiRR′;
• and
• L2 is selected from the group consisting of a direct bond, O, S, NR, CRR′, and SiRR′;
• ring B, ring E, and ring F are each independently 5-membered or 6-membered aromatic rings;
• each of RA, RB, RC, RD, RE, and RF independently represents zero, mono, or up to the maximum allowed number of substitutions to its associated ring;
• each of R, R′, RA, RB, RC, RD, RE, and RF is independently a hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, boryl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof, and
• any two adjacent R, R′, RA, RB, RC, RD, RE, or RF can be joined or fused together to form a ring.

An organic light emitting device (OLED) comprising:

• an anode;
• a cathode;
• and
• an organic layer disposed between the anode and the cathode, wherein the organic layer comprises a compound comprising a ligand LA of
• wherein:
• ligand LA is coordinated to a metal M selected from the group consisting of Ru, Os, Ir, Pd, Pt, Cu, Ag, and Au;
• Z1-Z2 are each independently C or N with one being N and the other C;
• ring B is a 5-membered or 6-membered aromatic ring;
• X is C or N;
• each of X1—X7 is independently C or N;
• if metal M is Ir, Os, or Ru, then at least two of adjacent X1—X3 are C, and are fused to a structure of Formula II
• if metal M is Pt, Pd, Cu, Ag, or Au, then at least two of adjacent X1—X4 are C, and are fused to a structure of Formula II;
• each of K1 and K2 is independently a direct bond, O, or S;
• Y is selected from the group consisting of O, S, Se, BR, NR, CRR′, and SiRR′;
• L1 is selected from the group consisting of O, S, NR, CRR′, and SiRR′;
• each of RA, RB, RC, RD, RE, and RF independently represents zero, mono, or up to the maximum allowed number of substitutions to its associated ring;
• each of R, R′, RA, RB, RC, RD, RE, RF, and RX is independently a hydrogen or a substituent selected from the group consisting of deuterium, halogen, alkyl, cycloalkyl, heteroalkyl, heterocycloalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, boryl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carboxylic acid, ether, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof;
• any two adjacent R, R′, RA, RB, RC, RD, RE, RF, or RX can be joined or fused together to form a ring;
• wherein the ligand LA can be joined with other ligands to form a tridentate, tetradentate, pentadentate, or hexadentate ligand;
• and
• wherein, if the compound has a structure of
• where no two RE are joined or fused to form a ring, then at least one of the following is true:
• (i) RX comprises at least three aromatic moieties that are not fused to each other and at least one of the aromatic moieties is substituted, or (ii) RX comprises at least 5 aromatic rings and two are heteroaromatic rings, or (iii) RX comprises silyl and at least three aromatic moieties that are not fused to each other.