1,8-Naphthyridine metal complexes

Naphthylamine, 1-phcnylazo-metal complexes structure, 6,44 1,8-Naphthyridine metal complexes, 2, 92, 93 Neel temperature, 1, 258 Neocupferron... 

A detailed study of the infrared spectra of a number of 1,8-naphthyridine-metal complexes has established that the M—N stretching vibrations decrease consistently when the complexes containing a four-membered ring are compared with similar complexes in which the ligand is a,a -bipyridine. Thus, this technique lends itself admirably to the structure determination of these complexes.104,111... 

Naphthoic acid, 3-hydroxy-7-sulfonato-metal complexes structure, 482 1,8-Naphthyridine metal complexes, 92,93 Neoeupferron metd complexes, 509-512 Neptunium complexes cupferron, 510 Neutron diffraction hydrates... 

The chemistry of naphthyridines was last reviewed in this series in 1970. Since that time a veritable explosion of publications has occurred emphasizing the chemistry of the naphthyridine metal complexes, their medicinal... 

Naphthyridine will form complexes of the type ML2 with Cu(II), Co(II) and Ni(II) but not with Cd(II), Pd(II), Ba(II) or Zn(II) (66MI21101). 1,5-Naphthyridine 1,5-dioxide forms coordination compounds with Cu(II) salts (76IC2916), and metal complexes of l,7-naphthyridin-8-ones with Cu(II), Ni(II), Fe(II) and Fe(III) have also been prepared (54JCS505). A more detailed account of metal ion-naphthyridine complex formation is given in a recent review (83AHC(33)147). 

Metal complexes, analogous to 8-hydroxyquinoline,54,151 of 4-hydroxy-1,5-naphthyridine,54 8-hydroxy-1,6-naphthyridine,54 151 and 8-hydroxy-1,7-naphthyridine54 with Cu(II), Ni(II), Fe(II), and Fe(III) have been prepared. The hydroxynaphthyridines chelate less readily than 8-hydroxyquinoline since they are weaker bases.151... 

A, whereas the N2—Hg distance is 2.03 A. The Hg—Hg bond in this compound is extremely short. The 1,8-naphthyridine nickel complex, [Ni2(l,8-naphthyridine)4Br2]+ PF , also has a very short metal metal bond length. However, all four of the naphthyridines are bridge-bonded and each metal atom is coordinated in a square-planar array by four nitrogen atoms.108... 

Note Typical metallic complexes are those of l,8-naphthyridine-2,7-dicar-boxylic acid with Ni,368 Rh,498 and Ru 498 and of 2,7-bis[jV, (V-di(carbox-ymethyl)aminomethyl]-l,8-naphthyridine (14) with Eu and Tb (for luminescence analysis).714... 

Because of structural uncertainties and confusing nomenclature, much of the early literature is, frankly, of little more than historical interest. However, after 1930, when most authors adopted the present Chemical Abstracts naming (see Note on Nomenclature that follows), a reliable body of literature gradually accumulated on all six systems, albeit at very different rates. For example, data on the 1,8-naphthyridines greatly outnumbered those on the other systems, probably as a result of the discovery of significant antimicrobial properties associated with nalidixic acid as well as the intrinsic suitability of the 1,8-system for metal complexation. 

The naphthyridines and their derivatives exhibit various types of biological activity, and the organic chemistry has been frequently reviewed.1-6 The preparation of the ligands can be found in the references to their metal complexes. 

Finally, the structural characteristics of the 1,8-naphthyridines favour their behavior as bidentate and dinucleating ligands, thus leading to short metal-metal separations in late transition-metal complexes,24"26 and to the stabilization of mixed-valence complexes.27,28 The dinuclear ruthenium complex [ Ru(napy)(H20)2 (/i-Cl)(/i-0H)](C104)2 is a stable and active catalyst for the oxidation of alcohols and the epoxidation of alkenes, while its mononuclear precursor is much less active.29... 

Wang and Wong prepared the quinoline and 1,8-naphthyridine analogues, 518 and 519 of 74. The barriers in 518 and 519 are 109 and 108 kj mol, respectively. All barriers are suitable for separation of enantiomers by chiral HPLC (95T6941). Several transition metals complexes of 74, 518, and 519 were reported as well as their X-ray data. 

Molecular orbital studies on fluxional behavior of metal complexes containing monodentate diimines are of obvious relevance to one-end-off mechanisms for dissociation, as in the classic case of [Fe(bipy)3]. In this approach the behavior of the monodentate diimines is treated alongside that of such diaza-ligands as pyridazine (10), phthalazine (11), and naphthyridine (12)/ ... 

Several chelating or metal-complexing polymers were reported in Volume 1 of the series (p. 362). There is still considerable activity in this area and polystyrene remains one of the most widely-used supports. Selective chelate-forming ion-exchange resins were prepared from polystyrene by nitration followed by reduction, diazotization then coupling with aromatic amines and derivatives of phenol. Poly(styryl-l,8-naphthyridine) (7) also functions as a chelating agent with Cu ,... 

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