In:
Canadian Journal of Chemistry, Canadian Science Publishing, Vol. 81, No. 7 ( 2003-07-01), p. 872-881
Abstract:
The Os(P)(NO)(ONO) compounds (P = TTP, TMP, OEP, TmTP; TTP = 5,10,15,20-tetra-p-tolylporphyrinato dianion, TMP = 5,10,15,20-tetramesitylporphyrinato dianion, OEP = octaethylporphyrinato dianion, TmTP = tetra(m-tolyl)porphyrinato dianion) have been prepared from the reaction of the precursor carbonyl complexes Os(P)(CO) with excess nitric oxide. Nitrous oxide was detected as a by-product of the reaction. The IR spectra of the Os(P)(NO)(ONO) compounds (as KBr pellets) reveal bands in the 17901804 cm 1 range that are assigned to υ NO . The IR spectra also reveal two new bands for each complex in the 14951531 and 913962 cm 1 ranges indicative of O-bound nitrito ligands. The linearity of the bound NO groups and the O-binding of the trans nitrito ligands in the Os(P)(NO)(ONO) complexes are evident in the single-crystal X-ray crystal structures of the TTP and TMP derivatives. The kinetics of the reaction were studied by stopped-flow mixing techniques. Spectroscopic analysis of rapidly mixed solutions of Os(P)CO and NO in toluene showed a biphasic approach to the Os(P)(NO)(ONO) and N 2 O products, owing to the starting material Os(P)CO scavenging CO formed during the reaction to give Os(P)(CO) 2 (K CO = 10 6 M 1 ). The dicarbonyl was the only transient species observed. It is proposed that the rate-determining step of the reaction leading to Os(P)(NO)(ONO) is NO displacement of CO from Os(P)(CO) via initial formation of an unstable 19 electron Os(P)(NO)(CO) intermediate.Key words: osmium, nitric oxide, X-ray, nitrosyl, porphyrin, kinetics.
Type of Medium:
Online Resource
ISSN:
0008-4042
,
1480-3291
Language:
English
Publisher:
Canadian Science Publishing
Publication Date:
2003
detail.hit.zdb_id:
1482256-8
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