Organic electroluminescent materials and devices

A compound represented by formula (2):

• wherein M21 represents iridium;
• each of A21 to A23 independently represents a carbon atom;
• Z21 comprises an aromatic 6-membered nitrogen-containing heterocyclic ring, which can be further substituted, wherein Z21 is coordinated to M21;
• Z22 is selected from the group consisting of a benzene ring and a naphthalene ring, either of which can be further substituted;
• Z22 can form a condensed ring with other rings;
• L22-E21-L23 represents an acetylacetone bidentate ligand, which can be further substituted;
• k represents an integer of 2;
• l represents an integer of 1;
• each of S21 and S22 independently represents a neopentyl group;
• and
• each of n and m represents an integer of 0 to 4, n+m is an integer of 1 to 4.

An organic electroluminescence device comprising a substrate;

• a pair of electrodes on the substrate;
• and at least one organic layer between the electrodes, wherein the organic layer comprises a compound of formula (1):
• wherein M11 represents a metal belonging to Groups 8 to 11 in the periodic table of elements;
• A11 represents a nitrogen atom or a carbon atom;
• X11 represents an oxygen atom, a sulfur atom, a substituted or unsubstituted nitrogen atom or a single bond;
• Y11 represents a linking group or a single bond;
• L11 represents a partial structure having an atom bonded to X11;
• Z11 comprises an aromatic 6-membered nitrogen-containing heterocyclic ring, which can be further substituted, coordinated to M11;
• each of L12 and L13 represents a carbon atom, a nitrogen atom, an oxygen atom or a phosphorus atom;
• E11 represents an atomic group for forming a bidentate ligand together with L12 and L13;
• k represents an integer of 1 to 3;
• l represents an integer of 0 to 2, k+l is 2 or 3;
• S11 is a substituent for substituting on at least either one of L11 and Z11 and represents a neopentyl group;
• and
• n represents an integer of 1 to 4.