Organic electroluminescent materials and devices

1. A compound comprising a ligand L A of Formula I

wherein:

ring A and ring B are each independently a 5-membered or 6-membered carbocyclic or heterocyclic ring;

Z 1 to Z 5 are each independently C or N;

X is BR 1 , BR 1 R 2 , AlR 1 , AlR 1 R 2 , GaR 1 , GaR 1 R 2 , InR 1 , InR 1 R 2 , CO, SO 2 , or POR 1 ;

Y is NR 3 , NR 3 R 4 , PR 3 , O, S, SO, SO 2 , CR 3 R 4 , SiR 3 R 4 , PR 3 R 4 , or GeR 3 R 4 ;

R A and R B each represent zero, mono, or up to a maximum allowed substitution to its associated ring;

each of R A , R B , R 1 , R 2 , R 3 , and R 4 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;

when X is BR 1 R 2 , Y is NR 3 , NR 3 R 4 , PR 3 , O, S, SO, SO 2 , SiR 3 R 4 , PR 3 R 4 , or GeR 3 R 4 ;

when X is BR 1 or POR 1 , Y is NR 3 or O, and ring A is a 5-membered heterocyclic ring, at least one of the following is true:

i) R 1 and R 3 join together to form a ring;

ii) R 1 joins with R A to form a ring;

iii) R 3 joins with R B to form a ring;

iv) at least one of Z 2 or Z 4 is N; and

any two substituents can be joined or fused together to form a ring,

wherein the ligand L A is coordinated to a metal M by the two indicated dash lines;

wherein the ligand L A can be joined with other ligands to form a tridentate, tetradentate, pentadentate, or hexadentate ligand;

wherein the ligand L A is selected from the group consisting of:

wherein R Z and R C have the same definition as R A or R B ; and R 7 , R 8 , R 9 , R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , and R 17 have the same definition as R 1 through R 4 ;

or

the ligand L A is selected from the group consisting of the structures defined below;

Ligand #

Structure of L Aa

R A1 —R A13 , L Q1 —L Q5

L Aa 1-X(i)(o)(p), wherein i, o, and p are each an integer from 1 to 86, wherein L Aa 1-x(1)(1)(1) to L Aa 1-X(86)(86)(86), having the structure

wherein R A1 = R A i, R A7 = R A o, and R A8 = R A p, wherein X = Al, Ga, or In,

L Aa 2-X(i)(s), wherein i is an integer from 1 to 86, and s is an integer from 1 to 14, wherein L Aa 2-X(1)(1) to L Aa 2-X(86)(14), having the structure

wherein R A1 = R A i, and L Q1 = L Q s, wherein X = Al, Ga, or In,

L Aa 3-(o)(p)(t), wherein o and p are integers from 1 to 86 and t is an integer from 89 to 184, wherein L Aa 3- (1)(1)(89) to L Aa 3-(86)(86)(184), having the structure

wherein R A7 = R A o, R A8 = R A p, and L Q2 = L Q t,

L Aa 4-(s)(t), wherein s is an integer from 1 to 14 and t is an integer from 89 to 184, wherein L Aa 4-(1)(89) to L Aa 4-(14)(184), having the structure

wherein L Q1 = L Q s, and L Q2 = L Q t,

L Aa 5-X(i)(o)(p), wherein i, o, and p are each an integer from 1 to 86, wherein L Aa 5-x(1)(1)(1) to L Aa 5-X(86)(86)(86), having the structure

wherein R A1 = R A i, R A7 = R A o, and R A8 = R A p, wherein X = B, Al, Ga, or In,

L Aa 6-X(i)(j)(k)(o)(p), wherein i, j, o, and p are each an integer from 1 to 86 and k is an integer from 1 to 77, wherein L Aa 6-X(1)(1)(1)(1)(1) to L Aa 6- X(86)(86)(77)(86)(86), having the structure

wherein R A1 = R A i, R A7 = R A j, R A3 = R A k, R A7 = R A o, and R A8 = R A p, wherein X = B, Al, Ga, or In,

L Aa 7-X(k)(m)(n)(p), wherein k, m, and n are each an integer from 1 to 77 and p is an integer from 1 to 86, wherein L Aa 7-X(1)(1)(1)(1) to L Aa 7-X(77)(7)(77)(86), having the structure

wherein R A3 = R A k, R A5 = R A m, R A6 = R A n, and R A8 = R A p, wherein X = B, Al, Ga, or In,

L Aa 8-X(k)(p)(w), wherein k is an integer from 1 to 77, p is an integer from 1 to 86, and w is an integer from 15 to 43, wherein L Aa 8-X(1)(1)(15) to L Aa 8- X(77)(86)(43), having the structure

wherein R A3 = R A k, R A8 = R A p, and L Q5 = L Q w, wherein X = B, Al, Ga, or In,

L Aa 9-X(k)(m)(n)(p), wherein k, m, and n are each an integer from 1 to 77 and p is an integer from 1 to 86, wherein L Aa 9-X(1)(1)(1)(1) to L Aa 9- X(77)(77)(77)(86), having the structure

wherein R A3 = R A k, R A5 = R A m, R A6 = R A n, and R A8 = R A p, wherein X = B, Al, Ga, or In,

L Aa 10-X(k)(p)(w), wherein k is an integer from 1 to 77, p is an integer from 1 to 86, and w is an integer from 15-43, wherein L Aa 10-X(1)(1)(15) to L Aa 10- X(77)(86)(43), having the structure

wherein R A3 = R A k, R A8 = R A p, and L Q5 = L Q w, wherein X = B, Al, Ga, or In,

L Aa 11-X(k)(p), wherein is an integer from 1 to 77 and p is an integer from 1-86, wherein L Aa 11-X(1)(1) to L Aa 11-X(77)(86), having the structure

wherein R A3 = R A k, and R A8 = R A p, wherein X = B, Al, Ga, or In,

L Aa 12-X(i)(k)(o)(p), wherein i, o, and p are each an integer from 1 to 86 and k is an integer from 1 to 77, wherein L Aa 12-X(1)(1)(1)(1) to L Aa 12- X(86)(77)(86)(86), having the structure

wherein R A1 = R A i, R A3 = R A k, R A7 = R A o, and R A8 = R A p, wherein X = Al, Ga, or In,

L Aa 13-X(i)(j)(k)(l)(o)(p), wherein i, j, o, and p are each an integer from 1 to 86 and k and l are integers from 1 to 77, wherein L Aa 13-X(1)(1)(1)(1)(1)(1) to L Aa 13-X(86)(86)(77)(77)(86)(86), having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, R A4 = R A l, R A7 = R A o, and R A8 = R A p, wherein X = B, Al, Ga, or In,

L Aa 14-X(i)(k)(s), wherein i is an integer from 1 to 86, k is an integer from 1 to 77, and s is an integer from 1 to 14, wherein L Aa 14-X(1)(1)(1) to L Aa 14- X(86)(77)(14), having the structure

wherein R A1 = R A i, R A3 = R A k, and L Q1 = L Q s, wherein X = Al, Ga, or In,

L Aa 15-X(i)(j)(k)(l)(s), wherein i and j are each an integer from 1 to 86, k and l are each an integer from 1 to 77, and s is an integer from 1 to 14, wherein L Aa 15-X(1)(1)(1)(1)(1) to L Aa 15- X(86)(86)(77)(77)(14), having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, R A4 = R A l, and L Q1 = L Q s, wherein X = B, Al, Ga, or In,

L Aa 16-(k)(o)(p)(t), wherein k is an integer from 1 to 77, o and p are each an integer from 1 to 86, and t is an integer from 89 to 184, wherein L Aa 16- (1)(1)(1)(89) to L Aa 16-(77)(86)(86)(184), having the structure

wherein R A3 = R A k, R A7 = R A o, R A8 = R A p, and L Q2 = L Q t,

L Aa 17-(k)(l)(o)(p)(t), wherein k and l are each an integer from 1 to 77, o and p are each an integers from 1 to 86, and t is an integer from 15 to 88, wherein L Aa 17-(1)(1)(1)(1)(15) to L Aa 17- (77)(77)(86)(86)(88), having the structure

wherein R A3 = R A k, R A4 = R A l, R A7 = R A o, R A8 = R A p, and L Q2 = L Q t,

L Aa 18-X(i)(j)(o)(p)(u), wherein i, j, o, and p are each an integer from 1 to 86, and u is an integer from 15 to 24, wherein L Aa 18-X(1)(1)(1)(1)(15) to L Aa 18- X(86)(86)(86)(86)(24), having the structure

wherein R A1 = R A i, R A2 = R A j, R A7 = R A o, R A8 = R A p, and L Q3 = L Q u, wherein X = B, Al, Ga, or In,

L Aa 19-(o)(p)(t)(u), wherein o and p are each an integer from 1 to 86, t is an integer from 15 to 88, and u is an integer from 15 to 24, wherein L Aa 19- (1)(1)(15)(15) to L Aa 19-(86)(86)(88)(24), having the structure

wherein R A7 = R A o, R A8 = R A p, L Q2 = L Q t, and L Q3 = L Q u,

L Aa 20-(k)(s)(t), wherein k is an integer from 1 to 77, s is an integer from 1 to 14, and t is an integer from 89 to 184, wherein L Aa 20-(1)(1)(89) to L Aa 20- (77)(14)(184), having the structure

wherein R A3 = R A k, L Q1 = L Q s, and L Q2 = L Q t,

L Aa 21-(k)(l)(s)(t), wherein k and l are each an integer from 1 to 77, s is an integer from 1 to 14, and t is an integer from 15 to 88, wherein L Aa 21-(1)(1)(1)(15) to L Aa 21-(77)(77)(14)(88), having the structure

wherein R A3 = R A k, R A4 = R A l, L Q1 = L Q s, and L Q2 = L Q t,

L Aa 22-X(i)(j)(s)(u), wherein i and j are each an integer from 1 to 86, s is an integer from 1 to 14, and u is an integer from 15 to 24, wherein L Aa 22- X(1)(1)(1)(15) to L Aa 22-X(86)(86)(14)(24), having the structure

wherein R A1 = R A i, R A2 = R A j, L Q1 = L Q s, and L Q3 = L Q u, wherein X = B, Al, Ga, or In,

L Aa 23-(s)(t)(u), wherein s is an integer from 1 to 14, t is an integer from 15 to 88, and u is an integer from 15 to 24, wherein L Aa 23-(1)(15)(15) to L Aa 23- (14)(88)(24), having the structure

wherein L Q1 = L Q s, L Q2 = L Q t, and L Q3 = L Q u,

L Aa 24-X(o)(p)(v), wherein o and p are each an integer from 1 to 86, and v is an integer from 185 to 253, wherein L Aa 24-X(1)(1)(185) to L Aa 24- X(86)(86)(253), having the structure

wherein R A7 = R A o, R A8 = R A p, and L Q4 = L Q v, wherein X = B, Al, Ga, or In,

L Aa 25-X(s)(v), wherein s is an integer from 1 to 14, and v is an integer from 185 to 253, wherein L Aa 25- X(1)(185) to L Aa 25-X(14)(253), having the structure

wherein L Q1 = L Q s, and L Q4 = L Q v, wherein X = B, Al, Ga, or In,

L Aa 26-X(i)(o)(p)(q)(r), wherein i, o, and p are each an integer from 1 to 86, and q and r are each an integer from 1 to 77, wherein L Aa 26-X(1)(1)(1)(1)(1) to L Aa 26-X(86)(86)(86)(77)(77), having the structure

wherein R A1 = R A i, R A7 = R A o, R A8 = R A p, R A9 = R A q, and R A10 = R A r, wherein X = B, Al, Ga, or In,

LAa27-X(i)(q)(r)(s), wherein i is an integer from 1 to 86, q and r are each an integer from 1 to 77, and s is an integer from 1 to 14, wherein L Aa 27-X(1)(1)(1)(1) to L Aa 27-X(86)(77)(77)(14), having the structure

wherein R A1 = R A i, R A9 = R A q, R A10 = R A r, and L Q1 = L Q s, wherein X = B, Al, Ga, or In,

L Aa 28-(o)(p)(q)(r)(t), wherein o and p are each an integer from to 1 to 86, q and r are each an integer from 1 to 77, and t is an integer from 89 to 184, wherein L Aa 28-(1)(1)(1)(1)(89) to L Aa 28- (86)(86)(77)(77)(184), having the structure

wherein R A7 = R A o, R A8 = R A p, R A9 = R A q, R A10 = R A r, and L Q2 = L Q t,

L Aa 29-(q)(r)(s)(t), wherein q and r are each an integer from 1 to 77, s is an integer from 1 to 14, and t is an integer from 89 to 184, wherein L Aa 29-(1)(1)(1)(89) to L Aa 29-(77)(77)(14)(184), having the structure

wherein R A9 = R A q, R A10 = R A r, L Q1 = L Q s, and L Q2 = L Q t,

L Aa 30-X(i)(o)(p)(w), wherein i, o and p are each an integer from 1 to 86, and w is an integer from 15 to 43, wherein L Aa 30-X(1)(1)(1)(15) to L Aa 30- X(86)(86)(86)(43), having the structure

wherein R A1 = R A i, R A7 = R A o, R A8 = R A p, and L Q5 = L Q w, wherein X = B, Al, Ga, or In,

L Aa 31-X(i)(s)(w), wherein i is an integer from 1 to 86, s is an integer from 1 to 14, and w is an integer from 15 to 43, wherein L Aa 31-X(1)(1)(15) to L Aa 31- X(86)(14)(43), having the structure

wherein R A1 = R A i, L Q1 = L Q s, and L Q5 = L Q w, wherein X = B, Al, Ga, or In,

L Aa 32-(o)(p)(t)(w), wherein o and p are each an integer from 1 to 86, t is an integer from 89 to 184, and w is an integer from 15 to 43, wherein L Aa 32- (1)(1)(89)(15) to L Aa 32-(86)(86)(184)(43), having the structure

wherein R A7 = R A o, R A8 = R A p, L Q2 = L Q t, and L Q5 = L Q w,

L Aa 33-(s)(t)(w), wherein s is an integer from 1 to 14, t is an integer from 89 to 184, and w is an integer from 15 to 43, wherein L Aa 33-(1)(89)(15) to L Aa 33- (14)(184)(43), having the structure

wherein L Q1 = L Q s, L Q2 = L Q t, and L Q5 = L Q w,

L Aa 34-(m)(n)(p)(q)(r), wherein m, n, q and r are each an integer from 1 to 77, and p is an integer from 1 to 86, wherein L Aa 34-(1)(1)(1)(1)(1) to L Aa 34- (77)(77)(86)(77)(77), having the structure

wherein R A5 = R A m, R A6 = R A n, R A8 = R A p, R A9 = R A q, and R A10 = R A r,

L Aa 35-(m)(n)(p)(q)(r)(x), wherein m, n, q, r and x are each an integer from 1 to 77, and p is an integer from 1 to 86, wherein L Aa 35-(1)(1)(1)(1)(1)(1) to L Aa 35- (77)(77)(86)(77)(77)(77), having the structure

wherein R A5 = R A m, R A6 = R A n, R A8 = R A p, R A9 = R A q, R A10 = R A r, and R A11 = R A x,

L Aa 36-(k)(m)(n)(p)(q)(r), wherein k, m, n, q and r are each an integer from 1 to 77, and p is an integer from 1 to 86, wherein L Aa 36-(1)(1)(1)(1)(1)(1) to L Aa 36- (77)(77)(77)(86)(77)(77), having the structure

wherein R A3 = R A k, R A5 = R A m, R A6 = R A n, R A8 = R A p, R A9 = R A q, and R A10 = R A r,

L Aa 37-(k)(m)(n)(p)(q)(r)(x), wherein k, m, n, q, r and x are each an integer from 1 to 77, and p is an integer from 1 to 86, wherein L Aa 37-(1)(1)(1)(1)(1)(1)(1) to L Aa 37-(77)(77)(77)(86)(77)(77)(77), having the structure

wherein R A3 = R A k, R A5 = R A m, R A6 = R A n, R A8 = R A p, R A9 = R A q, R A10 = R A r, and R A11 = R A x,

L Aa 38-(m)(n)(p)(q)(r)(y)(z), wherein m, n, q, r, y and z are each an integer from 1 to 77, and p is an integer from 1 to 86, wherein L Aa 38-(1)(1)(1)(1)(1)(1)(1) to L Aa 38-(77)(77)(86)(77)(77)(77)(77), having the structure

wherein R A5 = R A m, R A6 = R A n, R A8 = R A p, R A9 = R A q, R A10 = R A r, R A12 = R A y, and R A13 = R A z,

L Aa 39-(k)(m)(n)(p)(q)(r)(y)(z), wherein k, m, n, q, r, y and z are each an integer from 1 to 77, and p is an integer from 1 to 86, wherein L Aa 39- (1)(1)(1)(1)(1)(1)(1)(1) to L Aa 39- (77)(77)(77)(86)(77)(77)(77)(77), having the structure

wherein R A3 = R A k, R A5 = R A m, R A6 = R A n, R A8 = R A p, R A9 = R A q, R A10 = R A r, R A12 = R A y, and R A13 = R A z,

L Aa 40-X(o)(p)(t), wherein o and p are each an integer from 1 to 86; wherein t is an integer from 89 to 184, 254 to 267; wherein L Aa 40-X(1)(1)(89) to L Aa 40- X(86)(86)(267), having the structure

wherein R A7 = R A o, R A8 = R A p, and L Q2 = L Q t, wherein X = Al, Ga, or In,

L Aa 41-X(s)(t), wherein s is an integer from 1 to 14 and t is an integer from 89 to 184, 254 to 267; wherein L Aa 41-X(1)(89) to L Aa 41-X(14)(267), having the structure

wherein L Q1 = L Q s, and L Q2 = L Q t, wherein X = Al, Ga, or In,

L Aa 42-X(k)(o)(p)(t), wherein k is an integer from 1 to 77, o and p are each an integer from 1 to 86; wherein t is an integer from 89 to 184, 254 to 267, wherein L Aa 42-X(1)(1)(1)(89) to L Aa 42-X(77)(86)(86)(267), having the structure

wherein R A3 = R A k, R A7 = R A o, R A8 = R A p, and L Q2 = L Q t, wherein X = Al, Ga, or In,

L Aa 43-X(k)(l)(o)(p)(t), wherein k and l are each an integer from 1 to 77, o and p are each an integer from 1 to 86; wherein t is an integer from 15 to 88, 268 to 345, wherein L Aa 43-X(1)(1)(1)(1)(15) to L Aa 43- X(77)(77)(86)(86)(345), having the structure

wherein R A3 = R A k, R A4 = R A l, R A7 = R A o, R A8 = R A p, and L Q2 = L Q t,; wherein X = Al, Ga, or In,

L Aa 44-X(o)(p)(t)(u), wherein o and p are each an integer from 1 to 86, and u is an integer from 15 to 24; wherein t is an integer from 15 to 88, 268 to 345, wherein L Aa 44-X(1)(1)(15)(15) to L Aa 44- X(86)(86)(345)(24), having the structure

wherein R A7 = R A o, R A8 = R A p, L Q2 = L Q t, and L Q3 = L Q u, wherein X = Al, Ga, or In,

L Aa 45-X(k)(s)(t), wherein k is an integer from 1 to 77, s is an integer from 1 to 14; wherein t is an integer from 89 to 184, 254 to 267; wherein L Aa 45- X(1)(1)(89) to L Aa 45-X(77)(14)(267), having the structure

wherein R A3 = R A k, L Q1 = L Q s, and L Q2 = L Q t, wherein X = Al, Ga, or In,

L Aa 46-X(k)(l)(s)(t), wherein k and l are each an integer from 1 to 77, s is an integer from 1 to 14; wherein t is an integer from 15 to 88, 268 to 345, wherein L Aa 46-X(1)(1)(1)(15) to L Aa 46- X(77)(77)(14)(345), having the structure

wherein R A3 = R A k, R A4 = R A l, L Q1 = L Q s, and L Q2 = L Q t, wherein X = Al, Ga, or In,

L Aa 47-X(s)(t)(u), wherein s is an integer from 1 to 14, u is an integer from 15 to 24; wherein t is an integer from 15 to 88, 268 to 345, wherein L Aa 47-(1)(15)(15) to L Aa 47-X(14)(345)(24), having the structure

wherein L Q1 = L Q s, L Q2 = L Q t, and L Q3 = L Q u, wherein X = Al, Ga, or In,

L Aa 48-X(o)(p)(q)(r)(t), wherein o and p are each an integer from 1 to 86, q and r are each an integer from 1 to 77; wherein t is an integer from 89 to 184, 254 to 267, wherein L Aa 48-X(1)(1)(1)(1)(89) to L Aa 48- X(86)(86)(77)(77)(267), having the structure

wherein R A7 = R A o, R A8 = R A p, R A9 = R A q, R A10 = R A r, and L Q2 = L Q t, wherein X = Al, Ga, or In,

L Aa 49-X(q)(r)(s)(t), wherein q and r are each an integer from 1 to 77, s is an integer from 1 to 14; wherein t is an integer from 89 to 184, 254 to 267, wherein L Aa 49-X(1)(1)(1)(89) to L Aa 49- X(77)(77)(14)(267), having the structure

wherein R A9 = R A q, R A10 = R A r, L Q1 = L Q s, and L Q2 = L Q t, wherein X = Al, Ga, or In,

L Aa 50-X(o)(p)(t)(w), wherein o and p are each an integer from 1 to 86, w is an integer from 15 to 43; wherein t is an integer from 89 to 184, 254 to 267, wherein L Aa 50-X(1)(1)(89)(15) to L Aa 50- X(86)(86)(267)(43), having the structure

wherein R A7 = R A o, R A8 = R A p, L Q2 = L Q t, and L Q5 = L Q w, wherein X = Al, Ga, or In,

L Aa 51-X(s)(t)(w), wherein s is an integer from 1 to 14, w is an integer from 15 to 43; wherein t is an integer from 89 to 184, 254 to 267, wherein L Aa 51- X(1)(89)(15) to L Aa 51-X(14)(267)(43), having the structure

wherein L Q1 = L Q s, L Q2 = L Q t, and L Q5 = L Q w, wherein X = Al, Ga, or In,

L Aa 52-X(i)(j)(k)(o)(p), wherein i, j, o, and p are each an integer from 1 to 86 and k is an integer from 1 to 77, wherein L Aa 52-X(1)(1)(1)(1)(1) to L Aa 52- X(86)(86)(77)(86)(86), having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, R A7 = R A o, and R A8 = R A p, wherein X = B, Al, Ga, or In,

L Aa 53-X(i)(o)(p), wherein i, o, and p are each an integer from 1 to 86, wherein L Aa 53-X(1)(1)(1) to L Aa 53-X(86)(86)(86), having the structure

wherein R A1 = R A i, R A7 = R A o, and R A8 = R A p, wherein X = B, Al, Ga, or In,

L Aa 54-X(i)(k)(o)(p), wherein i, o, and p are each an integer from 1 to 86 and k is an integer from 1 to 77, wherein L Aa 54-X(1)(1)(1)(1) to L Aa 54- X(86)(77)(86)(86), having the structure

wherein R A1 = R A i, R A3 = R A k, R A7 = R A o, and R A8 = R A p, wherein X = Al, Ga, or In,

L Aa 55-X(i)(j)(k)(l)(o)(p), wherein i, j, o, and p are each an integer from 1 to 86 and k and l are each an integer from 1 to 77, wherein L Aa 55- X(1)(1)(1)(1)(1)(1) to L Aa 55- X(86)(86)(77)(77)(86)(86), having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, R A4 = R A l, R A7 = R A o, and R A8 = R A p, wherein X = B, Al, Ga, or In,

L Aa 56-(i)(j)(k)(o)(p), wherein i, j, o, and p are each an integer from 1 to 86 and k is an integer from 1 to 77, wherein L Aa 56-(1)(1)(1)(1)(1) to L Aa 56- (86)(86)(77)(86)(86), having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, R A7 = R A o, and R A8 = R A p, wherein X = B, Al, Ga, or In,

L Aa 57-X(l)(k)(o)(p), wherein i, o, and p are each an integer from 1 to 86 and k is an integer from 1 to 77, wherein L Aa 57-X(1)(1)(1)(1) to L Aa 57- X(86)(77)(86)(86), having the structure

wherein R A1 = R A i, R A3 = R A k, R A7 = R A o, and R A8 = R A p, wherein X = Al, Ga, or In,

L Aa 58-(o)(p), wherein o and p are each an integer from 1 to 86, wherein L Aa 58-(1)(1) to L Aa 58-(86)(86), having the structure

wherein R A7 = R A o, and R A8 = R A p,

L Aa 59-(s), wherein s is an integer from 1 to 14, wherein L Aa 59-(1) to L Aa 59-(14), having the structure

wherein L Q1 = L Q s,.

L Aa 60-(k)(o)(p), wherein o and p are each an integer from 1 to 86 and k is an integer from 1 to 77, wherein L Aa 60-(1)(1)(1) to L Aa 60-(77)(86)(86), having the structure

wherein R A3 = R A k, R A7 = R A o, and R A8 = R A p,

L Aa 61-(k)(s), wherein k is an integer from 1 to 77 and s is an integer from 1 to 14, wherein L Aa 61-(1)(1) to L Aa 61-(77)(14), having the structure

wherein R A3 = R A k, and L Q1 = L Q s,

L Aa 62-(o)(p), wherein o and p are each an integer from 1 to 86, wherein L Aa 62-(1)(1) to L Aa 62-(86)(86), having the structure

wherein R A7 = R A o, and R A8 = R A p,

L Aa 63-(s), wherein s is an integer from 1 to 14, wherein L Aa 63-(1) to L Aa 63-(14), having the structure

wherein L Q1 = L Q s,

L Aa 64-(k)(o)(p), wherein o and p are each an integer from 1 to 86 and k is an integer from 1 to 77, wherein L Aa 64-(1)(1)(1) to L Aa 64-(77)(86)(86), having the structure

wherein R A3 = R A k, R A7 = R A o, and R A8 = R A p,

L Aa 65-(k)(s), wherein k is an integer from 1 to 77 and s is an integer from 1 to 14, wherein L Aa 65-(1)(1) to L Aa 65-(77)(14), having the structure

wherein R A3 = R A k, and L Q1 = L Q s,

L Aa 70-(i)(k)(o), wherein i and o are each an integer from 1 to 86, and k is an integer from 1 to 77, wherein L Aa 70-(1)(1)(1) to L Aa 70-(86)(77)(86), having the structure

wherein R A1 = R A i, R A3 = R A k, and R A7 = R A o,

L Aa 71-(i)(j)(k)(o), wherein i, j, and o are each an integer from 1 to 86, and k is an integer from 1 to 77, wherein L Aa 71-(1)(1)(1)(1) to L Aa 71-(86)(86)(77)(86), having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, and R A7 = R A o,

L Aa 72-(i)(j)(k)(l)(o), wherein i, j, and o are each an integer from 1 to 86, and k and l are each an integer from 1 to 77, wherein L Aa 72-(1)(1)(1)(1)(1) to L Aa 72- (86)(86)(77)(77)(86), having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, R A4 = R A l, and R A7 = R A o,

L Aa 73-(i)(k)(o), wherein i and o are each an integer from 1 to 86, and k is an integer from 1 to 77, wherein L Aa 73-(1)(1)(1) to L Aa 73-(86)(77)(86), having the structure

wherein R A1 = R A i, R A3 = R A k, and R A7 = R A o,

L Aa 74-(i)(j)(k)(o), wherein i, j, and o are each an integer from 1 to 86, and k is an integer from 1 to 77, wherein L Aa 74-(1)(1)(1)(1) to L Aa 74-(86)(86)(77)(86), having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, and R A7 = R A o,

L Aa 75-(i)(j)(k)(l)(o), wherein i, j, and o are each an integer from 1 to 86, and k and l are each an integer from 1 to 77, wherein L Aa 75-(1)(1)(1)(1)(1) to L Aa 75- (86)(86)(77)(77)(86), having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, R A4 = R A l, and R A7 = R A o,

L Aa 76-X(i)(j)(k)(o)(p), wherein i, j, k, o, and p are each an integer from 1 to 86 and k is an integer from 1 to 77, wherein L Aa 76-X(1)(1)(1)(1)(1) to L Aa 76- X(86)(86)(77)(86)(86), having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, R A7 = R A o, and R A8 = R A p, wherein X = B, Al, Ga, or In,

wherein R A i, R A j, R A k, R A l, R A m, R A n, R A o, R A p, R A q, R A r, R A x, R A y, and R A z have the following structures:

and

wherein L Q s, L Q t, L Q u, L Q v, and L Q w have the following structures:

2. The compound of claim 1 , wherein the compound has a formula of M(L A )x(L B )y(L C )z wherein L B and L C are each a bidentate ligand; and wherein x is 1, 2, or 3; y is 0, 1, or 2; z is 0, 1, or 2; and x+y+z is the oxidation state of the metal M.

3. The compound of claim 2 , wherein L B and L C are each independently selected from the group consisting of:

wherein

each of Y 1 to Y 13 is independently selected from the group consisting of carbon and nitrogen;

wherein Y′ is selected from the group consisting of B R e , N R e , P R e , O, S, Se, C═O, S═O, SO 2 , CR e R f , SiR e R f , and GeR e R f ; wherein R e and R f can be fused or joined to form a ring;

each of R a , R b , R e , and R d independently represents zero, mono, or up to a maximum allowed substitution to its associated ring;

each of R a , R b , R e , R d , R e and R f is independently a hydrogen or a substituent selected from the group consisting of deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, boryl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; and

any two adjacent substituents of R a , R b , R e , and R d can be fused or joined to form a ring or form a multidentate ligand.

4. The compound of claim 1 , wherein the compound is selected from the group consisting of:

5. The compound of claim 1 , wherein the compound is of the formula

wherein:

M is Pd or Pt;

rings C and D are each independently a 5-membered or 6-membered carbocyclic or heterocyclic ring;

M 1 and M 2 are each independently C or N;

A 1 -A 3 are each independently C or N;

K 1 and K 2 are each independently selected from the group consisting of a direct bond, O, and S;

L 1 -L 3 are each independently selected from the group consisting of a direct bond, O, S, CR′R″, SiR′R″, BR′, and NR′;

R′ and R″ are each independently selected from the group consisting of hydrogen or a substituent selected from the group consisting of deuterium, fluorine, alkyl, cycloalkyl, heteroalkyl, alkoxy, aryloxy, amino, silyl, boryl, alkenyl, cycloalkenyl, heteroalkenyl, aryl, heteroaryl, nitrile, isonitrile, sulfanyl, and combinations thereof;

m, n, and o are each independently 0 or 1;

m+n+o=2 or 3;

R C and R D each have the same definition as R A or R B ;

the remaining variables are the same as previously defined; and

any two substituents can be joined or fused together to form a ring.

6. An organic light emitting device (OLD) comprising:

an anode;

a cathode; and

an organic layer disposed between the anode and the cathode, wherein the organic layer comprises the compound of claim 1 .

7. A consumer product comprising an organic light-emitting device comprising:

an anode;

a cathode; and

an organic layer disposed between the anode and the cathode, wherein the organic layer comprises the compound of claim 1 .

8. A compound comprising a ligand L A of

wherein:

ring A and ring B are each independently a 5-membered or 6-membered carbocyclic or heterocyclic ring;

Z 1 to Z 5 are each independently C or N;

Y is NR 3 , NR 3 R 4 , PR 3 , O, S, SO, SO 2 , CR 3 R 4 , SiR 3 R 4 , PR 3 R 4 , or GeR 3 R 4 ;

R A and R B each represent zero, mono, or up to a maximum allowed substitution to its associated ring;

each of R A , R B , R 3 and R 4 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;

X is BR 1 , and R 1 has the formula

wherein:

ring C is a 5-membered or 6-membered carbocyclic or heterocyclic ring;

Z 6 , Z 7 , and Z 8 are each independently C or N;

R X has the same definition as R A or R B ;

R 5 and R 6 are each independently selected from the group consisting of hydrogen, alkyl, cycloalkyl, aryl, heteroaryl, and combinations thereof;

at least one of R 5 and R 6 is not hydrogen;

when Y is NR 3 or O, and ring A is a 5-membered heterocyclic ring, at least one of the following is true;

i) R 1 and R 3 join together to form a ring;

ii) R 1 joins with R A to form a ring;

iii) R 3 joins with R B to form a ring:

iv) at least one of Z 2 or Z 4 is N:

v) both Z 1 and Z 5 are C or N; and

any two substituents can be joined or fused together to form a ring,

wherein the ligand L A is coordinated to a metal M by the two indicated dash lines;

wherein M is selected from the group consisting of Os, Ir, Pd, Pt, Cu, Ag, and Au; and

wherein the ligand L A can be joined with other ligands to form a tridentate, tetradentate, pentadentate, or hexadentate ligand.

9. The compound of claim 8 , wherein Y is NR 3 .

10. The compound of claim 8 , wherein ring A is a 5-membered heterocyclic ring or ring B is a 6-membered carbocyclic or heterocyclic ring.

11. An organic light emitting device comprising:

an anode;

a cathode; and

an organic layer disposed between the anode and the cathode, wherein the organic layer comprises the compound of claim 8 .

12. A consumer product comprising an organic light-emitting device comprising:

an anode;

a cathode; and

an organic layer disposed between the anode and the cathode, wherein the organic layer comprises the compound of claim 8 .

13. A compound comprising a ligand L Ab of

wherein:

ring B is a 5-membered or 6-membered carbocyclic or heterocyclic ring;

X 1 , X 2 , and X 3 are each independently C or N, with at least two of them being C;

one of Z 1 and Z 5 is C and the other is N;

X is BR 1 , BR 1 R 2 , AlR 1 , AlR 1 R 2 , GaR 1 , GaR 1 R 2 , InR 1 , InR 1 R 2 , CO, SO 2 , or POR 1 ;

Y is NR 3 , NR 3 R 4 , PR 3 , O, S, SO, SO 2 , CR 3 R 4 , SiR 3 R 4 , PR 3 R 4 , or GeR 3 R 4 ;

R A and R B each represent zero, mono, or up to a maximum allowed substitution to its associated ring;

each of R A , R B , R 1 , R 2 , R 3 , and R 4 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;

the ligand L Ab is coordinated to a metal M;

M is selected from the group consisting of Ru, Os, Ir, Pd, Pt, Cu, Ag, and Au;

M can be coordinated to other ligands;

any two substituents can be joined or fused to form a ring; and

the ligand L Ab can be joined with other ligands to form a tridentate, tetradentate, pentadentate, or hexadentate ligand.

14. The compound of claim 13 , wherein X is BR 1 R 2 .

15. The compound of claim 13 , wherein Y is NR 3 or O.

16. The compound of claim 13 , wherein ring B is a 6-membered aromatic ring.

17. The compound of claim 13 , wherein L Ab is selected from the group consisting of:

wherein Y 1 is selected from the group consisting of O, S, NR 3 , PR 3 , CR 3 R 4 , and SiR 3 R 4 .

18. The compound of claim 13 , wherein L Ab is selected from the group consisting of the following structures,

L Abx

Structure of L Abx

R A1 , R A2 , R A3

x

L Ab1 to L Ab8000 having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, wherein i, j, and k are each an integer from 1 to 20,

wherein x = 20[20(i − 1) + (j − 1)] + k

L Ab8001 to L Ab16000 having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, wherein i, j, and k are each an integer from 1 to 20,

wherein x = 20[20(i − 1) + (j − 1)] + k + 8000

L Ab16001 to L Ab24000 having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, wherein i, j, and k are each an integer from 1 to 20,

wherein x = 20[20(i − 1) + (j − 1)] + k + 16000

L Ab24001 to L Ab32000 having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, wherein i, j, and k are each an integer from 1 to 20,

wherein x = 20[20(i − 1) + (j − 1)] + k + 24000

L Ab32001 to L Ab40000 having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, wherein i, j, and k are each an integer from 1 to 20,

wherein x = 20[20(i − 1) + (j − 1)] + k + 32000

L Ab40001 to L Ab48000 having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, wherein i, j, and k are each an integer from 1 to 20,

wherein x = 20[20(i − 1) + (j − 1)] + k + 40000

L Ab48001 to L Ab56000 having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, wherein i, j, and k are each an integer from 1 to 20,

wherein x = 20[20(i − 1) + (j − 1)] + k + 48000

L Ab56001 to L Ab64000 having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, wherein i, j, and k are each an integer from 1 to 20,

wherein x = 20[20(i − 1) + (j − 1)] + k + 56000

L Ab64001 to L Ab72000 having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, wherein i, j, and k are each an integer from 1 to 20,

wherein x = 20[20(i − 1) + (j − 1)] + k + 64000

L Ab72001 to L Ab80000 having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, wherein i, j, and k are each an integer from 1 to 20,

wherein x = 20[20(i − 1) + (j − 1)] + k + 72000

L Ab80001 to L Ab88000 having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, wherein i, j, and k are each an integer from 1 to 20,

wherein x = 20[20(i − 1) + (j − 1)] + k + 80000

L Ab88001 to L Ab96000 having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, wherein i, j, and k are each an integer from 1 to 20,

wherein x = 20[20(i − 1) + (j − 1)] + k + 88000

L Ab96001 to L Ab96400 having the structure

wherein R A1 = R A i, R A2 = R A j, wherein i and j are each an integer from 1 to 20,

wherein x = 20(i − 1) + j + 96000

L Ab96401 to L Ab96800 having the structure

wherein R A1 = R A i, R A2 = R A j, wherein i and j are each an integer from 1 to 20,

wherein x = 20(i − 1) + j + 96400

L Ab96801 to L Ab97200 having the structure

wherein R A1 = R A i, R A2 = R A j, wherein i and j are each an integer from 1 to 20,

wherein x = 20(i − 1) + j + 96800

L Ab97201 to L Ab97600 having the structure

wherein R A1 = R A i, R A2 = R A j, wherein i and j are each an integer from 1 to 20,

wherein x = 20(i − 1) + j + 97200

L Ab97601 to L Ab98000 having the structure

wherein R A1 = R A i, R A2 = R A j, wherein i and j are each an integer from 1 to 20,

wherein x = 20(i − 1) + j + 97600

L Ab98001 to L Ab10600 having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, wherein i, j, and k are each an integer from 1 to 20,

wherein x = 20[20(i − 1) + (j − 1)] + k + 98000

L Ab106001 to L Ab114000 having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, wherein i, j, and k are each an integer from 1 to 20,

wherein x = 20[20(i − 1) + (j − 1)] + k + 106000

L Ab114001 to L Ab122000 having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, wherein i, j, and k are each an integer from 1 to 20,

wherein x = 20[20(i − 1) + (j − 1)] + k + 114000

L Ab122001 to L Ab130000 having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, wherein i, j, and k are each an integer from 1 to 20,

wherein x = 20[20(i − 1) + (j − 1)] + k + 122000

L Ab130001 to L Ab138000 having the structure

wherein R A1 = R A i, R A2 = R A j, R A3 = R A k, wherein i, j, and k are each an integer from 1 to 20,

wherein x = 20[20(i − 1) + (j − 1)] + k + 130000

wherein R A i, R A j, and R A k have structures defined as follows:

19. An organic light emitting device comprising:

an anode;

a cathode; and

an organic layer disposed between the anode and the cathode, wherein the organic layer comprises the compound of claim 13 .

20. A consumer product comprising an organic light-emitting device comprising:

an anode;

a cathode; and

an organic layer disposed between the anode and the cathode, wherein the organic layer comprises the compound of claim 13 .