NOVELTY - Metal complex compounds (I) are new.    USE - (I) or the oligomers, polymers or the dendrimers are useful in at least one layer of electronic devices, preferably organic electroluminescent devices (preferred), organic integrated circuits, organic field-effect transistors, organic thin-film transistors, organic light-emitting transistors, organic solar cells, organic optical detectors, organic photoreceptors, organic field-quench devices, light-emitting electrochemical cells and organic laser diodes (all claimed).    ADVANTAGE - The organic electroluminescent device exhibits good service life and excellent efficiency.    DETAILED DESCRIPTION - Metal complex compounds of formula (M(L)n(L1)m) (I) are new.    either L = heterocyclyl moieties of formula (IIa) or (IIb); and    L1 = coligand; or    several L, L+L1 (bonded by single bond or by di- or trivalent bridge) = tridentate-, tetradentate-, pentadentate- or hexadentate ligand system;    M = transition metal;    X = CR or N;    Y1 = C(R1)2, Si(R1)2, PR1, P(=O)R1 or BR1;    Z = NR1, O or C(R1)2;    D1 = C or N, where at least one group D1 = N;    E = C or N, where at least one of the groups E and D1 in five-membered ring is N; either    R, R1 = 1-20C alkyl or 1-20C (thio)alkoxy (both linear) or 3-20C alkyl or 3-20C (thio)alkoxy (both branched or cyclic) or 2-20C alkenyl or 2-20C alkynyl (in all groups at least one non-adjacent CH2 group is optionally replaced by R2C=CR2, CC, Si(R2)2, C=O, NR2, O, S or CONR2, and at least one H is optionally replaced by D, F, Cl, Br, I or CN), (hetero)aromatic ring with 5-60 aromatic ring atoms, (hetero)aryloxy with 5-40 aromatic ring atoms, (hetero)aralkyl with 5-40 aromatic ring atoms, diarylamino with 10-40 aromatic ring atoms, diheteroarylamino with 10-40 aromatic ring atoms or arylheteroarylamino with 10-40 aromatic ring atoms (all optionally substituted by at least one group R2), H, D, F, Cl, Br, I, N(R2)2, CN, NO2, OH, COOH, C(=O)N(R2)2, Si(R2)3, B(OR2)2, C(=O)R2, P(=O)(R2)2, S(=O)R2, S(=O)2R2 or OSO2R2, where 1 group R is optionally and additionally coordinated to the metal; and    R2 = 1-20C alkyl or 1-20C (thio)alkoxy (both linear) or 3-20C alkyl or 3-20C (thio)alkoxy (both branched or cyclic) or 2-20C alkenyl or 2-20C alkynyl (in all groups at least one non-adjacent CH2 group is optionally replaced by R3C=CR3, CC, Si(R3)2, C=O, NR3, O, S or CONR3, and at least one H is optionally replaced by D, F, Cl, Br, I, CN or NO2), (hetero)aromatic ring with 5-60 aromatic ring atoms, (hetero)aryloxy with 5-40 aromatic ring atoms, (hetero)aralkyl with 5-40 aromatic ring atoms, diarylamino with 10-40 aromatic ring atoms, diheteroarylamino with 10-40 aromatic ring atoms or arylheteroarylamino with 10-40 aromatic ring atoms (all optionally substituted by at least one group R3), H, D, F, Cl, Br, I, N(R3)2, CN, NO2, Si(R3)3, B(OR3)2, C(=O)R3, P(=O)(R3)2, S(=O)R3, S(=O)2R3 or OSO2R3; or    2 adjacent R, 2 adjacent R1, R+R1, at least 2 adjacent R2, R2+R, R2+R1 = mono- or polycyclic and aliphatic or (hetero)aromatic ring; either    R3 = aliphatic and/or (hetero)aromatic 1-20C hydrocarbyl (in which at least one H is optionally replaced by F), H, D or F; or    at least 2 R3 = mono- or polycyclic and aliphatic ring;    n = 1-3; and    m = 0-4.    INDEPENDENT CLAIMS are also included for:    (1) preparing (I);    (2) an oligomer, polymer or dendrimer comprising (I) having at least one bond to the polymer, oligomer or the dendrimer; and    (3) a formulation comprising (I), the oligomer, polymer or dendrimer, and at least one further compound, preferably a solvent and/or a further organic or inorganic compound which is used in electronic device.