Metal carbonyl cyanides

Interpretation of potential constants application to study of bonding forces in metal cyanide complexes and metal carbonyls, L. H. Jones and B. I. Swanson, Acc. Chem. Res., 1976,9,128-134 (27). 

Carbonyl Nitric Oxides. Another group of metal-carbonyl complexes, worthy of investigation as CVD precursors, consists of the carbonyl nitric oxides. In these complexes, one (or more) CO group is replaced by NO. An example is cobalt nitrosyl tricarbonyl, CoNO(CO)3, which is a preferred precursor for the CVD of cobalt. It is a liquid with a boiling point of 78.6°C which decomposes at 66°C. It is prepared by passing NO through an aqueous solution of cobalt nitrate and potassium cyanide and potassium hydroxide. ... 

The interpretation of potential constants obtained from vibrational analyses of metal carbonyls (and cyanides)... 

Metalated aminomethyl cyanides are widely used as reagents for nucleophilic acylation64. There are few reports of the stereoselective alkylation of these reagents because upon hydrolysis, which is carried out to give the carbonyl compound, the stereocenter previously created is destroyed. A stereoselective alkylation would be valuable, of course, if in the following step the cyano group was modified or replaced in a stereoselective manner by another group. Examples of both processes have been reported. 

It is important to establish the main similarities and differences in the electronic spectra of isoelectronic metal carbonyls and cyanides and to relate these spectral comparisons to the nature of the M-CN and M—CO bonds. In this paper the electronic spectra of d6 metal carbonyls and cyanides are assigned on the basis of a derived molecular orbital energy level scheme. The differences in the energies erf the single electron molecular orbitals for representative metal hexa-carbonyls and hexacyanides are obtained and a general discussion erf electronic structure is presented. 

There will always be 36 electrons (6 from each ligand) to place in the molecular orbitals for the complex. In addition, the metal may furnish as many as 6 valence electrons for an octahedral metal carbonyl or cyanide complex. The ground state for a d6 metsl hexacarbonyl or hexacyanide is therefore... 

The d-d transitions in most of the d6 metal carbonyls and cyanides are hard to locate with certainty, since the large A-values mean that metal-to-ligand charge transfer may occur at about the same energy as the two bands due to the tagf -) - eg(cr ) transition. For the complexes in which the metal furnishes fewer than 6 valence electrons (such as the d6 Fe(CN)e3 ), additional charge-transfer bands due to ligand-to-metal transitions further obscure the weak d-d bands.8 Nevertheless, in many cases reliable values for A are available for M(CO) and M(CN)6n complexes. These A-vahies are summarized in Tahle III. 

The cyanocarbonylchromates(O) [Cr(CO)5CN]- and cis-[CifCOMCN) ] -, which are formed by the oxidation of [Cr l,(CO)s]2-with aqueous solutions of KCN or with (CN)2 or ICN have been discussed earlier (55, 56). Further studies have shown that the reaction of metal carbonyls or their derivatives with solutions of KCN in liquid NH3 is a most advantageous method for the synthesis of new cyanocarbonyl metalates of transition metals, since, in liquid NH3, alkali cyanides are not subject to solvolysis, and also since the broad temperature range of -78 to +120°C may be employed. Thus, we have been able to obtain quantitative yields of the tricyano-tricarbonyl metalates (0)/ac-[M(CO)3(CN)3]3 (M = Cr, Mo, W) by direct reaction of the hexacarbonyls (21) ... 

Carbides Transition Metal Solid-state Chemistry Carbon FuUerenes Carbonyl Complexes of the Transition Metals Carbonylation Processes by Homogeneons Catalysis Cyanide Complexes of the Transition Metals Intercalation Chemistry. 

Together with Ni(CO)4 andFe(CO)5, dicobaltoctacarbonyl, Co2(CO)g (1), was among the earliest metal carbonyls (see Metal Carbonyls) to be detected and characterized by Mond and coworkers." It was prepared from frnely divided metal (or by hydrogen reduction of the oxide, CoO) in a Cu-lined autoclave made from Ni steel at 150 °C and a CO pressure of 30-40 bar. Other preparations employ reductive carbonylation of cobalt salts, mainly Co(OAc)2, or the carbonylation of an alkaline cobalt cyanide solution. The acetate salt is also the common precursor for Co2(CO)g or Co(CO)4H in the Cocatalyzed hydroformylation (see Hydroformylation) process (Section HCo(CO)4 in Hydroformylation Reactions ). 

Certain classical coordination complexes (see Coordination Complexes) of iron (e.g. Prussian blue) will be dealt with in other articles (see Iron Inorganic Coordination Chemistry and Cyanide Complexes of the Transition Metals), as will much of the chemistries of iron carbonyls (see Metal Carbonyls) and iron hydrides (see Hydrides) (see Carbonyl Complexes of the Transition Metals Transition Metal Carbonyls Infrared Spectra, and Hydride Complexes of the Transition Metals). The use of organoiron complexes as catalysts (see Catalysis) in organic transformations will be mentioned but will primarily be covered elsewhere (see Asymmetric Synthesis by Homogeneous Catalysis, and Organic Synthesis using Transition Metal Carbonyl Complexes). 

---