Metal carbonyl nitrosyls

I remember with great satisfaction my collaboration with J. S. Anderson in the Heidelberg Institute. In 1932 he made the volatile, previously unrecognized as such, dinitrosyldicarbonyliron by the action of pure nitric oxide on a solution of Fe3(CO)12 in iron pentacarbonyl (98). The complex Fe(CO)2(NO)2 was a deep red liquid at room temperature. With this compound the isoelectronic series Ni(CO)4, Co(CO)3NO, Fe(CO)2(NO)2 arose, and in this manner the field of carbonyl nitrosyls was opened up. The next member of this isoelectronic series, Mn(CO)(NO)3, predicted by us in 1932, was discovered recently (99). A study of the chemical behavior of the carbonyl nitrosyls, namely the ready substitution of the CO but not of the NO groups, was essentially established by Anderson (100), with the isolation of the derivatives Fe(NO)2py2, Fe(NO)2(o-phen), Co(NO)(CO)(o-phen), and Co(NO)(CO)(PR3)2, etc. 

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. 

These results have been discussed by Seel in Structure and Valence Theory of Inorganic Nitric Oxide Complexes (102). In such complexes, nitric oxide is covalently bonded to the metal atom as the positive ion NO+, it being assumed that an electron is transferred to the metal. This allows the isoelectronic groups NO+, CO, CN to be considered together and permits understanding of such known series as [Fen(CN)5NO]2, [Fen(CN)5CO]3-, and [Fen(CN)5CN]4-. 

Together with H. Beutner we succeeded at last in discovering a quantitative synthesis of the anion [Fe(CO)3NO] from the system iron penta-carbonyl/nitrite/methylate (45), and thereby established the isoelectronic 

---

In this manner, the field of monohalide-metal nitric oxide complexes was developed, as well as the so-called nitroprussiates extensively studied by Nast and Proschel (104). Since these complexes do not contain CO groups as ligands a discussion of the noteworthy results falls outside the limits of this survey, although the field is closely related to the metal carbonyl nitrosyls. 

The substitution of a neutral ligand, including carbon monoxide, attached to a metal carbonyl complex by the nitrosyl cation, produces a cationic metal carbonyl nitrosyl. 

Metallocenes and related compounds for which mass spectral data have been reported are given in Tables I-XII, but in many cases only the molecular ion is reported. Metal carbonyls, nitrosyls and their derivatives, and fluorocarbon complexes are not discussed in this review, but Table XIX summarizes the compounds for which mass spectral data have been reported since Bruce s review (27). 

Scheme 4.5 T wo isoelectronic series of tetrahedral metal carbonyl and metal carbonyl nitrosyl compounds, prepared in the course of one century from 1890 to 1990 (with the names of the principal investigators and the date of discovery)...

Other useful methods involve displacement of CO by PF3 from mixed-metal carbonyl nitrosyl complexes (method C), passing C02 through a... 

The fact that in the formation of the MG bond in carbonyls the metal always donates an even number of electrons, and that in the nitrosyls the numlaer of electrons donated by the metal to the MN bond is always odd, is the reason for the formation of mono-metallic carbonyl-nitrosyl compounds, e.g. Go(GO)3NO. In addition to structure II for Go(GO)3NO, in which the nine electrons are employed in the formation of a and bonds,... 

Metal carbonyl halides are preferred for the noble metals because of their stability temperature range. Examples are Ru(CO)2l2, Os(CO)3Cl2, RhCl2, RhO(CO)3, IrCl2(CO)2, Pt(CO)Cl2, and Pt(CO)3Cl2. Metal carbonyl nitrosyls are also useful Cobalt is deposited from liquid CoNO(CO)3. 

The metal carbonyl nitrosyls never make much of an appearance in this report, so it was of some interest to see that Belkova and co-workers have made a detailed study of the structural and energetic aspects of hydrogen bonding and proton transfer to ReH2(CO)(NO)(PR3)2 and ReHCl(CO)(NO)(PMej)2 by combining IR and X-ray information. 

Carter, O. L., McPhail, A. T. Sim, G. A. (1967) Metal-carbonyl and metal-nitrosyl complexes. Part V. The crystal and molecular structure of the tricarbonylchromium derivative of methyl benzoate, J. Chem. Soc. A, 1619-1626. 

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. ... 

S. J. W. Price Decomposition of metal alkyls, aryls, carbonyls and nitrosyls, pp. 197-257 (156) see especially section 2, homogeneous decomposition of metal carbonyls, and section 3.1, homogeneous decomposition of metal alkyls and aryls (of Cu, Ag, Au). 

Nitrogen Groups in Metal Carbonyl and Related Complexes, 10, 115 Nitrosyls, 7, 211... 

The literature cited in this article covers references listed in chemical abstracts to the end of 1961 and in current chemical papers after that. A degree of selection has been exercised in omitting some references that are now of limited value. Although metal nitrosyls are included in the scope of this chapter, no kinetic data on their decomposition is available and they will not be considered further. The data on metal carbonyls is limited and will be dealt with in the first section. The decomposition of metal alkyls and aryls has been extensively investigated. These compounds will be discussed in groups based on the position of the central metal atom in the periodic table and, when warranted, a further subdivision will be made based on the attached organic radicals. 

Metal cluster compounds can be conveniently grouped into two classes (I) polynuclear carbonyls, nitrosyls. and related compounds and (II) halide and oxide complexes. The former group was included m Chapter 15. The second class will be discussed in this section.146... 

The first attempts to interpret Werner s views on an electronic basis were made in 1923 by Nevil Vincent Sidgwick (1873—1952) and Thomas Martin Lowry (1874—1936).103 Sidgwick s initial concern was to explain Werner s coordination number in terms of the sizes of the sub-groups of electrons in the Bohr atom.104 He soon developed the attempt to systematize coordination numbers into his concept of the effective atomic number (EAN).105 He considered ligands to be Lewis bases which donated electrons (usually one pair per ligand) to the metal ion, which thus behaves as a Lewis acid. Ions tend to add electrons by this process until the EAN (the sum of the electrons on the metal ion plus the electrons donated by the ligand) of the next noble gas is achieved. Today the EAN rule is of little theoretical importance. Although a number of elements obey it, there are many important stable exceptions. Nevertheless, it is extremely useful as a predictive rule in one area of coordination chemistry, that of metal carbonyls and nitrosyls. 

---