Organometallic nomenclature

In the chemical nomenclature organometallic compounds contain direct metal-carbon bonds, while this is not necessarily the case for metal compounds with organic ligands. In the scope of this review, however, this distinction is not always important. Therefore, mostly the shorter term organometallic compounds is used in a more general meaning. 

Nomenclature of organometallic compounds of the transition elements (lUPAC recommendations) 99PAC1557. 

The second edition of the well-known Red Book, the definitive recommendations of the lUPAC Commission on Nomenclature of Inorganic Chemistry, appeared in Pure Appl. Chem., 28, 1-110 (1971). It is also available separately as a hard-bound reprint. In this edition, the rules for naming organometallic compounds have been completely revised and extended, with introduction of the rj nomenclature for organic ligands. 

Organometallic compounds are defined as compounds containing a direct link between a carbon atom and a metal. What constitutes a metal for nomenclature purposes is really rather vague. The practice in nomenclature is to consider any element other than C, H and the rare gases to be metals if this is useful. The names of such compounds reflect their constitution and are drawn both from organic nomenclature and from inorganic nomenclatures. The names of organometallic compounds demonstrate that nomenclatures must be unified and adaptable to any situation. 

Thus organometallic compounds can be named by an additive or a substitutive process. Additive nomenclature is applicable to all organometallic compounds, but substitutive nomenclature is arbitrarily restricted to names of derivatives of specific metals, the elements of Groups 14, 15, 16 and 17, and boron. 

An area of current development is the nomenclature of organometallic compounds. Organometallic compounds of Main Group elements can, to a first approximation, be considered to be derivatives of hydrides, and the methods of substitutive nomenclature can be applied. Even then, the accessibility of different oxidation states, as with phosphorus(iii) and phosphorus(v), introduces complications. Transition metal organometallic compounds are even more difficult to treat, and the development of a unified, self-consistent and accepted and applied nomenclature is not easy. Witness the different ways (k, t and italicised symbols) for denoting donor atoms in ligands. 

The Editor would draw attention to the unsatisfactory state of the nomenclature of organometallic compounds in general. The designations of compounds in Volume XI. are those used in the original memoirs, since any attempt to alter these in a work of that description would only complicate matters. 

The present discussion of isomerism in coordination compounds is not, nor was it intended to be, comprehensive and exhaustive. The examples considered are an eclectic selection, and many important systems may have been neglected through ignorance. An obvious omission is any detailed consideration of polynuclear complexes139,256"259 and it is, of course, a quite arbitrary decision not to include any consideration of organometallic species. Other neglected issues, such as the development of a truly comprehensive system of stereochemical nomenclature, are perhaps not yet capable of solution. Nevertheless, it is to be hoped that the principal factors to be considered... 

In all cases the nomenclature adhered to is that used in the original memoirs, any alteration of which must be undertaken by an International Committee. For an author to make such alterations would merely mean that another set of names had been added to those already in existence, and would tend to add to the present confusion. The author, as in Volume II., again appeals to Chemical Societies to secure some definite standard nomenclature for organometallic compounds in general. 

A modification of (1) called "sandwich" nomenclature for that class of organometallic compounds called "metallocenes" ... 

Structure and Classification of Alcohols 425 10-3 Nomenclature of Alcohols and Phenols 427 10-4 Physical Properties of Alcohols 430 10-5 Commercially Important Alcohols 433 10-6 Acidity of Alcohols and Phenols 435 10-7 Synthesis of Alcohols Introduction and Review 438 Summary Previous Alcohol Syntheses 438 10-8 Organometallic Reagents for Alcohol Synthesis 440 10-9 Addition of Organometallic Reagents to Carbonyl Compounds 443... 

Interaction of re-type CO orbitals with the s valence atomic orbitals is only possible in high coordination sites (in the organometallic nomenclature these are called bridging sites, denoted i, p.3, and p4 for sites involving 2, 3 and 4 metal atoms, respectively). As illustrated in Fig. 4.3 they can then interact with asymmetric group orbitals that are linear combinations of atomic s orbitals of the surface atoms. 

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