Carbonyls nitrosyl

Early e.d. studies of Fe(CO)2(NO)2 and Co(CO)3NO indicated a tetrahedral arrangement of the four ligands with 

The Ru and Os compounds of the type M3(CO)i o(NO)2 are interesting for they possess double NO bridges. The two shorter sides of the isosceles triangle correspond to normal metal-metal bonds (2-87 A) (a). 

Many carbonyls have been prepared containing atoms of two or more different elements, some with only CO ligands and others with ligands of various types. The special interest lies in the metal-metal bonds and in the stereochemistry of the metal atoms. We give in Table 22.9 a few simple examples of typical molecules  

The compound Fe5(CO)isC is produced in small quantity when Fe3(CO)j2 is heated in petroleum ether with methylphenylacetylene. It has the tetragonal pyramidal structure shown in Fig. 22.11(a), in which C is located just below the 

Compounds of metals containing hydrocarbon radicals or molecules are numerous. The simplest contain only metal and hydrocarbon radical (metal alkyls and aryls) or unsaturated hydrocarbon molecules (for example, Cr(C6H5)2), while in others there are also ligands such as halogens or CO. Because they are most closely related to the metal carbonyls we deal first with transition-metal compounds containing 

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Used industrially for the manufacture of nitric acid and nitrosyl carbonyls, in the bleaching of rayon, as a stabilizer for propylene and methyl ether, and as a medication. 

Consideration of the relative donor abilities of nitrosyl, carbonyl, and phosphine groups as measured by their ionization potentials, provides an explanation for variations in the molecular ionization potentials of these complexes (103, 194). As shown in Table III (Section IX) the ionization potentials decrease on introduction of the phosphine ligand, and parallel the corresponding decrease in ionization potentials of the phosphine ligands. Similar correlations were made for vco and vNO in the infrared spectra. 

An example of type 66b is the mononuclear nitrosyl (or it can be a nitrosyl-carbonyl) compound 67a. Examples of the bridge structures are binuclear compounds 67b [103a] and the complex pM2(NO)(CH3COO)2]2 CH2C12 with Pd NO coordination [103b] ... 

With respect to the derivatives of metal carbonyls, the substituted metal carbonyls of the VIB Group (e.g., Mo(CO)apya), the halogenocar-bonyls of iron, ruthenium, iridium, and platinum, the hydridocarbonyls H2Fe(CO)4 and HCo(CO)4 discovered in 1931 and 1934, and the nitrosyl carbonyls FelCOj NOjg and Co(CO)3NO were the most important (/). The known anionic CO complexes were limited to [HFe(CO)J and [Co(CO)J-. For studies of substitution reactions of metal carbonyls at this time, work was almost totally limited to reactions involving the classical N ligands such as NH3, en, py, bipy, and phen. 

Formation of Ni(CO)4 or Co(CO)4- by the cyanide method depends upon the stepwise substitution of the anion of the cyano complex by the iso-electronic carbon monoxide molecule. By treating Co2(CO)8 with potassium cyanide we obtained cyanocarbonyls of cobalt of low oxidation number (83). In reactions of the nitrosyl carbonyls of iron and cobalt, Behrens (86) substituted all the CO groups with CN to give K3[Co(NO)(CN)3] or... 

A rational method of preparation for the nitrosyl carbonyls of iron and cobalt was discovered by my former co-worker F. Seel (101) by acidic decomposition of the appropriate carbonylmetallate solution in the presence of nitrite. 

Dipole moment measurements, first carried out in our Munich Institute by E. Weiss (108), provided evidence of the very slight polar character of the metal-CO and metal-NO bonds. Similar measurements supplied information about stereochemistry for example, of cw-I2Fe(CO)4 (108), (Ph3P)3Fe(CO)2 (51), and [Fe(CO)3SEt]2 (90), as well as of the phosphine-containing nitrosyl carbonyl manganese compounds (105). 

An iron nitrosyl carbonyl cation is prepared by disproportionation of mercurybis(iron nitrosyl tricarbonyl) in the presence of tris(dimethyl-amino)phosphine (159). 

This potassium salt, K4Ni2(CN)6, may be further reduced by potassium in liquid ammonia to yield a yellow substance, K4Ni(CN)4. This has nickel in the zero-valent state and is thus comparable to the metal carbonyls, Fe(CO)5 and Ni(CO)4 (p. 157), to cobalt nitrosyl carbonyl Co(CO)4NO, and to the metal ammoniates Ca(NH3)6 and Pt(NH3)2. However, K4Ni(CN)4, and the closely related acetylene derivative, K4Ni(C=CH)4, are especially unusual, for in them, the zero-valent metal has been incorporated into an anion, whereas in the carbonyls and metal ammoniates, the zerovalent metals are present as uncharged species. 

More recently Behrens and co-workers15 were able to prepare the series of monocyano nitrosyl carbonyls by reactions such as equation (1). The Mn° compounds obtained in this work are listed in Table 6. Na[Mn(CN)(CO)3(NO)] dissolves readily in polar solvents such as water, ethanol, acetone or THF, but the solutions, even in the absence of light and air, are unstable. Crystalline salts, which are air stable, were obtained by adding such a solution to an excess of the appropriate cation. The related isonitrile species were prepared by alkylation of the cyano anions with R304. ... 

Octaethylporphyrin (OEP) affords three osmium nitrosyl complexes Os(NO)(OMe)(OEP), made from Os(CO)py(OEP), methanol and NO 232 with HF this yields Os(NO)F(OEP)232 and with HC104 it gives 0s(N0)(0C103)(0EP).2SS The nitrosyl carbonyl complex [Os(NO)(CO)Cl2(PPh3)2]BF4 is made by reaction of Os(NO)(CO)Cl(PPh3)2 with HBF4.223... 

The nitrosonium cation [NO]+ is isoelectronic with CO and accordingly many mixed nitrosyl-carbonyl complexes are known. For electron counting purposes, the neutral molecule is considered to act as a 3 (or occasionally 1) VE donor. Thus various series of isoelectronic complexes can be envisaged (Table 3.5). The majority of synthetic routes to nitrosyl-carbonyl complexes involve (i) photochemical CO substitution or metal-metal bond cleavage by NO (ii) electrophilic attack by nitrosonium salts, e.g. [NO]BF4 or nitrosyl halides (e.g. C1NO) upon electron-... 

At this point in time NO has been the most successful reagent for the synthesis of nitrosyl carbonyl clusters. It is usually used as the Bp4 or PFe salt, which should be sublimed prior to use, and in all successful uses... 

PPN(N02) [PPN = bis(triphenylphosphine)nitrogen(l+)] has been found to be particularly successful as a mild reagent for converting metal carbonyls into nitrosyl carbonyl complexes (32-37). Equations (16) and... 

The most unambiguous approach to the assignment of C or N is the use of neutron diffraction. The neutron scattering power of C and N differs enough that even in disordered compounds the occupancies of C and N can be assigned. The only report of this technique for nitrosyl carbonyl complexes is for HW2(CO)9(NO) (58). 

Ru3(CO)i2, which suggests that the bridging nitrosyl ligands do not act as electron wells in the same fashion proposed for mononuclear nitrosyl carbonyl complexes. 

Nitrosyl complexes are of considerable structural and chemical interest. Direct syntheses from the corresponding carbonyls are reported here for two nitrosyl-carbonyl clusters containing double nitrosyl bridges. ( Caution. Considerable amounts of toxic nitric oxide are used in these reactions, which should therefore be carried out in an efficient hood.)... 

Nitric oxide loses an electron rather easily to formaiiitrusoniumcaiior yci its tendency lu undergo reduction oUcn causes difficullies when it is used as a reagent for synthesis of nitrosyl carbonyl complexes. How can you rationalize the ease of oxidation of NO with its case of reduction ... 

Tetrahedral carbonyls and nitrosyl-carbonyls. Lecture lOICCC... 

The nitrosyl carbonyl has not been identified, but crude products contain infrared absorption bands which have been attributed to such a compound. 

The nitrosyl carbonyls such as Co (NO) (CO)3 are much more stable than the nitrosyls themselves. Nitrosyl hahdes, Fe(NO)gX, Co(NO)2X and Ni(NO)X are known their stability falls from Fe to Ni and from I to Cl. Fluorides are... 

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