Iron complexes isocyanides

In a related reaction, isocyanides can be converted to aromatic aldimines by treatment with an iron complex followed by irradiation in benzene solution RNC -I- CftHe PhCH=NR. ... 

The well-known alkylation of ferrocyanide ion to form isocyanide iron complexes (48) can be explained by an insertion mechanism if the metal is alkylated initially, and then metal alkyl adds across a cyanide group. This mechanism also explains how external radioactive cyanide ion can enter the isocyanide ligands (48). 

C2H,N, Pyridine, 3,5-dimethyl-palladium complex, 26 210 CbHsNO, Benzoyl isocyanide chromium com-C HbO, Ethanone, 1-phenyl-manganese complex, 26 156-158 CBH, 02, Methyl benzoate chromium complex, 26 32 C H i, o-Xylylene magnesium complex, 26 147 ChH P, Phosphine, dimethylphenyl-iron complex, 26 61 ruthenium complex, 26 273 ChH12, 1,5-Cyclooctadiene iridium complex, 26 122 ruthenium complexes, 26 69-72, 253-256 ChH OjPS, 2-Butenedioic acid, 2-(dimethylphosphinothioyl)-dimethyl ester, manganese complex, 26 163... 

At the present time we have no certain knowledge of the state of the heme in these 450 nm species. We do not know if there are heme aggregates although they are unlikely. It is therefore reasonable to look at systems where the haem is aggregated as well as those where it is not in order to see how the absorption spectra can be mimic-ed. It seems reasonable to assume that the iron is low-spin in the carbon monoxide, isocyanide, and nitric oxide complexes as no high-spin iron complexes of this type are known. In the high-spin or low-spin state it may be that the thiol is weakly bound, if at all, for Fe(II) heme in models or in hemoglobin does not bind to thiols. In an attempt to understand these spectra we shall use a semi-empirical approach based on the theoretical discussion in the previous article (52) and elaborated in what follows immediately. Only Fe(II) complexes will be analysed as the Fe(III) proteins have been previously examined (52). 

Cyanotrimethylsilane, (CH3)3SiCN. This silane is present in solution in part as the isocyanide isomer, (CH3)3SiNC. And indeed it is more useful than NaCN for cyanation of the iron complex l2 to provide 2 and 3, intermediates in a projected synthesis of tridachione. 

Structures of Tetrakis(methyl isocyanide)iron Complexes... 

Insertion of isocyanide carbon atoms into the Cr—carbene bond of [(CO)5CrC(OMe)Me] gave aziridinylcarbene complexes (CIV), some reactions of which are summarized in Scheme 2 28, 198). Cyclic carbene groups (CV)-(CVIII), in which the carbene carbon atom is part of an aromatic six-electron Tr-system, have been reported to form pentacarbonyl chromium and tetracarbonyl iron complexes 383, 384). Related to carbene... 

Structures of Tctrakis(methyl isocyanide)iron Complexes Preparations of (Methyl isocyanide)iron Compounds... 

Pentacarbonyl iron is fairly inert to substitution reactions, and attempts to prepare Fe(CO)5- (CNR) (n = 1-5) by the direct reaction of Fe(CO)5 with isocyanides in Carius tubes has produced only the complexes Fe(CO)s (CNR) (n = 1 and 2). The products were obtained as mixtures that required separation. Other syntheses, including photochemical and trimethylamine N-oxide-promoted displacement of carbonyl groups, or other means, give the same products in variable yield. Procedures based on diiron nonacarbonyl and triiron dodecacarbonyl have produced similar results. The only zero-valent iron complex Fe(CO)5 (CNR) where n > 2 is the complex Fe(CNR)5 prepared either by metal vapor synthesis techniques or by sodium amalgam reduction of iron(II) bromide in the presence of isocyanide. ... 

It has been known from the 1970s that an iron complex can cleave the C-H bond of an arene [57, 58]. However, the exploitation of this reactivity for the development of a catalytic reaction has been largely neglected to date. An early attempt was described in 1987 [59], when Jones reported that an iron-isocyanide complex can insert the isocyanide group into the C-H bond of benzene upon irradiatirHi with light, and in the presence of added isonitrile and high dilution, the reaction was catalytic in iron, albeit the turnover was low (Eq. 23). 

The isocyanide ligand, CNR, is formally isolobal with a carbene ligand. Several studies have investigated iron(Ill) porphyrin isocyanide complexes which have the general formula [FeCPorKCNR) ]. However, these studies have mostly been concerned with spin state and spectroscopic properties rather than chemical transformations and will not be discussed in detail here. Crystallographic details are given for two of the complexes. " ... 

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