Synthesis, characterization, solid-state molecular structures, and deprotonation reactions of cationic alcohol complexes of osmium nitrosyl porphyrins

New alkoxide (OEP)Os(NO)(OR) (OEP = 2,3,7,8,12,13,17,18-octaethylporphyrinato dianion; R = ethyl, isopropyl, hexyl, cyclohexyl) compounds and alcohol (OEP)Os(NO)(HOR)]+ complexes (R = methyl, ethyl, isopropyl, hexyl, cyclohexyl) have been prepared in high yields and have been fully characterized by IR, 1H NMR, and UV-vis spectroscopy, and by elemental analyses. The (OEP)Os(NO)(OEt) compound was characterized by single-crystal X-ray crystallography. The cationic aqua and alcohol (OEP)Os(NO)(HOR)]+ complexes (R = ethyl, isopropyl, hexyl) complexes were also characterized by single-crystal X-ray crystallography, and the latter represent the first osmium alcohol structures to be reported. The electrophilic (OEP)Os(NO)]+ cation in the (OEP)Os(NO)(HOR)]+ complexes renders the coordinated alcohol ligands susceptible to deprotonation by pyridine to produce the corresponding alkoxide (OEP)Os(NO)(OR) derivatives. A one-pot reaction sequence for the preparation of new (OEP)Os(NO)(OR) complexes from (OEP)Os(NO)(OEt) was developed, which was based on (i) initial protonation of the ethoxide compound to give (OEP)Os(NO)(HOEt)]+, (ii) alcohol substitution by ROH to give (OEP)Os(NO)(HOR)]+, and (iii) deprotonation of the latter by pyridine to give (OEP)Os(NO)(OR).