The reaction of 5-hydroxy-2-nitrosophenol (mnrH), 5-hydroxy-6-methyl-2-nitrosophenol (6-MemnrH). 2 4-dinitrosooresorcinol (dnrH2) and substituted dinitrosoresorcinols (X-dnrH2) with various metal salts gave monomeric, dimeric and polymeric metal complexes such as M(mnr)2 (M=Cu, Ni and Fe); Cu(OH)(mnr); M(dnr)(M=Ni or Cu). The complexes of type M(mnr)j , M(6-Memnr)2 and M(dnr) (M=Cu or Ni) form 1:2 adducts with pyridine. These complexes were investigated using spectroscopic, thermogravimetric and magnetochemical techniques, and where appropriate by Mossbauer spectroscopy. The complexing behaviour of 3-methyl-4-oxime-IH-pyrazol-4, 5-dione (poH) and 3-methyl-4-oxime-l-phenvl-lH-pyrazol-4,5-dione (PpoH) with nickel(II) and copper(II) has been reinvestigated. Three new iron(II) complexes derived from these ligands have been prepared either by the reaction of PpoH with iron(II) under aqueous conditions or by the reaction of poH with iron pentacarbonyl in anhydrous THF. The latter reaction also afforded a number of organic products, the formation of which has been rationalised in terms of nitrene intermediates. The complexes Fe(Ppo)2.H2O, Fe(Ppo)2 .2py and Fe(po)2.H2O were found to be high spin. This property contrasts the behaviour of iron(II) complexes derived from 2-nitrosophenols, which are low spin, and is rationalised in terms of conjugation effects and the bonding character of the pyrazol-4, 5-dione monooxime ligand. The interaction of Cu(mnr)2. 2py with triphenylphosphine gave several products including a phenoxazinone and a novel phenoxazinone phosphorus ylid whose structure was elucidated by X-ray crystallography. The complex Cu(6-Memnr)2. 2py behaved similarly towards triphenylphosphine. The synthetic significance of these reactions is discussed. Kinetic studies on the reaction between triphenylphosphine and Cu(mnr)2 .2py indicate that adduct formation takes place initially. It is suggested that subsequent deoxygenative decomposition of this adduct leads to the products. Attempts to clarify the proposed mechanism through the use of insoluble polymer supports were not fruitful.
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