NOVELTY - Metal complexes (I) of bipolar, non-macrocyclic, tetradentate chelating ligands are new. Also new are polymers (A) containing (I); and several classes of ligands.    USE - (I) are useful as electron transport materials, hole blocking agents, electroluminescence matrix materials or singlet or triplet emitters, and are useful as functional materials in opto-electronic components. Electronic components containing (I) (specifically organic light-emitting diodes, integrated circuits, field effect transistors, thin film transistors, solar cells or laser diodes) are claimed.    ADVANTAGE - (I) are thermal stable, non-hygroscopic and resistant to hydrolysis and aggregation, and can be easily purified, stored, transported and utilized. The opto-electronic functions of (I) are readily controlled by suitable choice of metals and ligands. (I) show high efficiency when used as electron transport materials or hole blocking agents in electroluminescence apparatus; have narrow emission bands and pure emission colors; and are readily soluble in organic solvents. (I) can be prepared simply, efficiently and reproducibly in high purity; (I) having a purity of more than 99% (determined by 1H-NMR and/or HPLC) are claimed.    DETAILED DESCRIPTION - New, preferably neutral, metal complexes are of formula (I), and comprise a metal complexed with a tetradentate ligand (Lig) of formula L1-V-L2.    Met = metal;    V = bridging group containing 1-40 Group III - VI non-transition element atoms;    L1, L2 = same or different (preferably the same) partial ligands, covalently bonded to each other and of formula Cy1-Cy2;    Cy1, Cy2 = optionally substituted, saturated, unsaturated homocyclic or heterocyclic ring, each bonded (via a ring atom or an atom bonded to the ring) to a the metal by an ionic, covalent or coordination bond);    L3 = mono- or bidentate, neutral or monoanionic ligand; and    a = 0-2.    INDEPENDENT CLAIMS are also included for:    (a) the preparation of (I);    (b) new conjugated, partially conjugated and/or non-conjugated polymers (A) containing at least one compound (I) (preferably bonded via a substituent R on V); and    (c) 30 classes of new ligands (Lig) (II), e.g. the tetracyclic compounds of formulae (IIA) - (IIH) and various asymmetric analogs, the compounds bis-(6-phenyl-2-pyridyl)-methane, bis-(6-phenyl-2-pyridyl)-ketone, bis-(6-(1-hydroxy (sic)-3,5-di-tert. butyl)-phenyl)-phenyl-2-pyridyl)-methanol, 2,2'-thio-bis-(3-cyano-2,4-diphenyl)-pyridine and bis-(6-(3-phenyl)phenyl-2-pyridyl)-methane being excluded.    L = C, N or P;    Q = N, O, S, Se or Te;    T = N or P;    X = CR, N or P;    Y = NR1, O, S, Se, Te, SO, SeO, TeO, SO2, SeO2 or TeO2;    c = 0 or 1;    Z = BR1, (CR2)B(CR2), O-R1B-O. O-(R1O)B-O; CR2O-R1B-OCR2, (CR2CR2)R1B(CR2CR2). C=O, C=NR1, C=S, CR2, CR(OH), CR(OR1), C(NR1)2, (CR2)R2C(CR2), (CR2CR2)R2C(CR2CR2), (SiR2)R2C(SiR2), (SiR2CR2)R2C(CR2SiR2), (CR2SiR2)R2C(SiR2CR2), (SiR2SiR2)R2C(SiR2SiR2), cis-RC=CR, o- or m-C6H4, SiR2, Si(OH)2, Si(OR1)2, (CR2)R2Si(CR2), (CR2CR2)R2Si(CR2CR2), (SiR2)R2Si(SiR2), (SiR2CR2)R2Si(CR2SiR2), (CR2SiR2)R2Si(SiR2CR2), (SiR2SiR2)R2Si(SiR2SiR2), R1N, (CR2)R1N(CR2), (CR2CR2)R1N(CR2CR2), FP, FPO, R1P, R1As, R1Sb, R1Bi, R1PO, R1AsO, R1SbO, R1BiO, R1PSe, R1AsSe, R1SbSe, R1BiSe, R1PTe, R1AsTe, R1SbTe, R1BiTe, O-R1PO-O, O-(R1O)PO-O, CR2O-R1PO-OCR2, OCR2-R1PO-CR2O, O, S, Se, (CR2)O(CR2). (CR2)S(CR2), (CR2)(O)S(CR2) or (CR2)(O)2S(CR2) (or asymmetric analogs);    R = H, F, Cl, Br, NO2 or CN; linear, branched or cyclic alkyl or alkoxy of 1-20C (optionally substituted by one or more F and optionally having one or more non-adjacent CH2 replaced by CR1=CR1, Ctriple bondC, Si(R1)2, Ge(R1)2, Sn(R1)2, CO, CS, CSe, C=NR1, O, S, NR1 or CONR1); or aryl, heteroaryl, aryloxy or arylamino of 4-14C (optionally substituted by one or more non-aromatic groups R); or multiple R groups (on same or different rings) may together complete an expanded mono- or polycyclic, aliphatic or aromatic ring system; and    R1, R2 = H or 1-20C aliphatic or aromatic hydrocarbyl.