Organic nitroso compounds bind to metals in several ways, but most commonly as monodentate N-bonded ligands. Also known are O-bonded, η2-N,O-bonded. Dimers of organic nitroso compounds also bind in a κ2--O,O bidentate manner. Illustrative are Ru(acac) 2(C 6H 5NO) 2, where a pair nitrosobenzenes are monodentate, and [Ru(acac) 2(μ–C 6H 5NO)] 2 where two nitrosobenzenes bridge.[2]
Arylnitroso compounds with a flanking hydroxy group are a well-developed, e.g. 1-nitroso-2-naphthol. They are precursors to anionic N,O chelating ligands. Chelating dinitrosoarenes are uncommon but have been investigated.[3]
Synthesis
Organic nitroso complexes can be prepared from preformed organic nitroso precursors. These precursors usually exist as N-N bonded dimers, but the dimer dissociates readily. This direct method is used to give W(CO)5(tert-BuNO) (where tert-Bu is (CH 3) 3C).[4] The Fe-porphyrin complex depicted below is prepared by this route. More complicated but more biorelevant routes involve degradation of precursors such as nitrobenzene and phenylhydroxylamine.[5]
Ni(PEt 3) 4 + i–PrNO 2 → Ni(PEt 3) 2(η2−i–PrNO) + PEt 3 + OPEt 3 (Et = C2H5, i-Pr = (CH3)2CH)
The coupling of organic ligands and nitric oxide is yet another route.[1]
Connection to methemoglobinemia
Structure of Fe(octaethylporphyrin)(C6H5NO)(imidazole). This synthetic complex is thought to resemble heme inhibited by nitroso benzene. Color code: red = O, blue = N, Fe, gray = C, white = H.
Methemoglobinemia is a disorder where a large fraction of hemoglobin in one's blood has converted to inactive forms, generically called methemoglobin. Since methemoglobin is not an oxygen-carrier, methemoglobinemia is a serious disorder, sometimes fatal. Exposure to nitrobenzene, aniline, and their derivatives cause this disorder, which is attributed to their conversion to nitrosobenzene (and derivatives), which inactivate hemoglobin by forming a complex with the Fe center, precluding binding of O2.[6]
Related compounds
As indicated by the applications in dyeing, chelating aryl nitroso compounds often form deeply colored complexes
Cupferron, C6H5N(O-)NO, an anionic O-O chelating proligand was once a popular reagent for the analysis of metal ions.
Millon's reagent, which involves nitroso-based ligands, was once a test for proteins
References
↑ 1.01.1Lee, Jonghyuk; Chen, Li; West, Ann H.; Richter-Addo, George B. (2002). "Interactions of Organic Nitroso Compounds with Metals". Chemical Reviews102 (4): 1019–1066. doi:10.1021/cr0000731. PMID11942786.
↑Dey, Sanchaita; Panda, Sanjib; Ghosh, Prabir; Lahiri, Goutam Kumar (2019). "Electronically Triggered Switchable Binding Modes of the C -Organonitroso (ArNO) Moiety on the {Ru(acac)2} Platform". Inorganic Chemistry58 (2): 1627–1637. doi:10.1021/acs.inorgchem.8b03191. PMID30615436.
↑Chan, Siu-Chung; England, Jason; Wieghardt, Karl; Wong, Chun-Yuen (2014). "Trapping of the putative 1,2-dinitrosoarene intermediate of benzofuroxan tautomerization by coordination at ruthenium and exploration of its redox non-innocence". Chem. Sci.5 (10): 3883–3887. doi:10.1039/C4SC01185F.
↑Pilato, R. S.; McGettigan, C.; Geoffroy, G. L.; Rheingold, A. L.; Geib, S. J. (1990). "tert-Butylnitroso Complexes. Structural Characterization of W(CO)5(N(O)Bu-tert) and [CpFe(CO)(PPh3)(N(O)Bu-tert)]+". Organometallics9 (2): 312–17. doi:10.1021/om00116a004.
↑Berman, R. S.; Kochi, J. K. (1980). "Kinetics and Mechanism of Oxygen Atom Transfer from Nitro Compounds Mediated by Nickel(0) Complexes". Inorganic Chemistry19: 248–254. doi:10.1021/ic50203a050.
↑Godbout, Nathalie; Sanders, Lori K.; Salzmann, Renzo; Havlin, Robert H.; Wojdelski, Mark; Oldfield, Eric (1999). "Solid-State NMR, Mössbauer, Crystallographic, and Density Functional Theory Investigation of Fe−O2and Fe−O2Analogue Metalloporphyrins and Metalloproteins". Journal of the American Chemical Society121 (16): 3829–3844. doi:10.1021/ja9832820.
