Nitric Oxide Dioxygenation by O Adducts of Manganese Porphyrins.

We describe here nitric oxide dioxygenation (NOD) by the dioxygen manganese porphyrin adducts Mn(Por)(η-O) (Por = the -tetra-phenyl or -tetra--tolylporphyrinato dianions, TPP and TTP). The Mn(Por)(η-O) was assembled by adding O to sublimed layers of Mn(Por). When NO was introduced and the temperature was slowly raised from 80 to 120 K, new IR bands with correlated intensities grew concomitant with depletion of the υ(O) band.

Six-Coordinate Nitrato Complexes of Iron Porphyrins with Trans S-Donor Ligands.

The reaction of dimethyl sulfide (DMS) and tetrahydrothiophene (THT) with thin, amorphous layers of the nitrato complexes Fe(Por)(η-ONO) (Por = meso-tetraphenylporphyrinato dianion or meso-tetra- p-tolylporphyrinato dianion) at low temperature leads to formation of the corresponding six-coordinate complexes Fe(Por)(L)(η-ONO) (L = DMS, THT) as characterized by Fourier transform infrared and optical spectroscopy measurements. Adduct formation was accompanied by bidentate-to-monodentate linkage isomerization of the nitrato ligand, with the Fe center remaining in a high-spin electronic state. These adducts are thermally unstable; warming to room temperature restores the initial Fe(Por)(η-ONO) species.

Six-Coordinate Ferrous Nitrosyl Complex Fe(TTP)(PMe)(NO) (TTP = meso-Tetra-p-tolylporphyrinato Dianion).

Low-temperature in situ Fourier transform infrared and UV-vis measurements show that trimethylphosphine (PMe) reacts with microporous layers of Fe(TTP)(NO) (TTP = meso-tetra-p-tolylporphyrinato dianion; NO = nitric oxide) to form the previously unknown six-coordinate complex Fe(TTP)(PMe)(NO). Upon warming this compound to room temperature in the presence of excess phosphine, the NO ligand is completely replaced by phosphine, resulting in formation of the bis(trimethylphosphine) complex Fe(TTP)(PMe). Simultaneously, the NO released oxidizes free PMe to the corresponding phosphine oxide (OPMe) with concomitant formation of nitrous oxide (NO).

Six-coordinate nitrito and nitrato complexes of manganese porphyrin.

Reaction of small increments of NO2 gas with sublimed amorphous layers of Mn(II)(TPP) (TPP = meso-tetra-phenylporphyrinato dianion) in a vacuum cryostat leads to formation of the 5-coordinate monodentate nitrato complex Mn(III)(TPP)(η(1)-ONO2) (II). This transformation proceeds through the two distinct steps with initial formation of the five coordinate O-nitrito complex Mn(III)(TPP)(η(1)-ONO) (I) as demonstrated by the electronic absorption spectra and by FTIR spectra using differently labeled nitrogen dioxide. A plausible mechanism for the second stage of reaction is offered based on the spectral changes observed upon subsequent interaction of (15)NO2 and NO2 with the layered Mn(TPP).

Nitric oxide interaction with oxy-coboglobin models containing trans-pyridine ligand: two reaction pathways.

The oxy-cobolglobin models of the general formula (Py)Co(Por)(O2) (Por = meso-tetraphenyl- and meso-tetra-p-tolylporphyrinato dianions) were constructed by sequential low-temperature interaction of Py and dioxygen with microporous layers of Co-porphyrins. At cryogenic temperatures small increments of NO were introduced into the cryostat and the following reactions were monitored by the FTIR and UV-visible spectroscopy during slow warming. Similar to the recently studied (NH3)Co(Por)(O2) system (Kurtikyan et al.