Complex diamagnetic

Six-coordinate organoiron porphyrin nitrosyl complexes, Fe(Por)(R)(NO), were prepared from Fe(Por)R (Por = OEP or TPP R = Me, n-Bu, aryl) with NO gas. The NMR chemical shifts were typical of diamagnetic complexes, and the oxidation state of iron was assigned as iron(ll). ... 

A ruthenium porphyrin hydride complex was lirst prepared by protonation of the dianion, [Ru(TTP) in THF using benzoic acid or water as the proton source. The diamagnetic complex, formulated as the anionic Ru(If) hydride Ru(TTP)(H )(THF)l , showed by H NMR spectroscopy that the two faces of the porphyrin were not equivalent, and the hydride resonance appeared dramatically shifted upheld to —57.04 ppm. The hydride ligand in the osmium analogue resonates at —66.06 ppm. Reaction of [Ru(TTP)(H)(THF)j with excess benzoic-acid led to loss of the hydride ligand and formation of Ru(TTP)(THF)2. 

A dark red, amido-bridged complex is prepared from Na/Hg reduction of [cp Ir (/u2-NH)2-C10H6-1,8 (/i2- Br) I rep ] Br yielding (276), a diamagnetic complex with an Ir11—Ir11 metal bond... 

The NMR spectra [27] of [Fe(HB(pz)3)2] exhibit shifted resonances as would be expected for a paramagnetic complex, but the shifts are intermediate between those observed for fully diamagnetic complexes and the comparable resonances in the fully high-spin [Fe(HB(3,5-(CH3)2pz)3)2] complex. In contrast to the increasing chemical shifts, either in the positive or negative direction, that follow the Curie law, observed at lower temperatures for [Fe(HB(3,5-(CH3)2pz)3)2] and [Fe(HB(3,4,5-(CH3)3pz)3)2], the chemical shifts of [Fe(HB(pz)3)2] decrease as the temperature is decreased, as would be expected for an increase in the percentage of the low-spin complex. 

The first indication that such O-coordinated (phenoxyl)metal complexes are stable and amenable to investigation by spectroscopy was obtained when the electrochemistry of the colorless, diamagnetic complexes [Mm(LBu2)], [Mm(LBuMet)] (M = Ga, Sc) containing three coordinated phenolates in the cis-position relative to each other was investigated in acetonitrile solutions (142). A representative structure of [Scm(LBuMet)] is shown in Fig. 12. 

Given the redox non-innocent character of the quinoidal ligand, the present diamagnetic complex can in principle be formulated either as Cr(0)-(quinone)3, or as Cr(VI)-(catechol)3, or as Cr(III)-(semiquinone)3. As a matter of fact, based also on the C-O distance, it has been preferentially assigned as [Crni(3,5-di-Bu sq)3].54... 

Rate parameters for only a few substituted ethylenediamine chelates have been reported and, until recently, none for ethylenediamine chelates because the chemical shifts between the two forms in diamagnetic complexes (on which the analysis depends) are small and because of the extreme lability of the system. For the interconversion of the 5 and X, forms of... 

The diamagnetic complex is not reduced further by the cyclooctatetraene dianion. This prevents the conversion of the azoxybenzene anion-radicals into azodianions. Potassium cation plays an important role in this limitation of the reduction process, which, generally, proceeds readily (the... 

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