Organo-Group IV compounds

A136. K. U. Ingold and B. P, Roberts, Free Radical Substitution Reactions Bimolecular Homolytic Substitutions (Sh2 Reactions) at Saturated Multivalent Atoms. Wiley (Interscience), New York, 1971. 245 pp. There is a section on Sa2 reactions in organo-group IV compounds,... 

Two-component systems are obtained by the interaction of transition metal compounds of groups IV-VIII of the periodic system with or-ganometallic compounds of groups I-III elements (Ziegler-Natta catalysts). An essential feature of the formation of the propagation centers in these catalysts is the alkylation of the transition metal ions by an organo-metallic cocatalyst. 

Keto Derivatives of Group IV Organometalloids, 7, 95 Lewis Base-Metal Carbonyl Complexes, 3, 181 Ligand Substitution in Transition Metal ir-Complexes, 10, 347 Literature of Organo-Transition Metal Chemistry 1950-1970, 10, 273 Literature of Organo-Transition Metal Chemistry 1971,11, 447 Literature of Organo-Transition Metal Chemistry 1972, 12, 379 Mass Spectra of Metallocenes and Related Compounds, 8, 211 Mass Spectra of Organometallic Compounds, 6, 273... 

In order to better understand bonding in main-group organo compounds and to obtain data on main-group species which can act as ligands in transition metal complexes, study of the negative ion states of various saturated and unsaturated Group IV, V, VI, and VII hydrocarbons was undertaken. One example of this work is the series of para-disubstituted benzenes ... 

Lukevits, E. Y. Voronkov, M. G. Organic Insertion Reactions of Group IV Elements" Consultants Bureau New York, 1966. Eabom, C. Bott, R. W. In Organo-metallic Compounds of the Group IV Elements, Vol. 1, Part I A. G. McDiarmid, Ed. Marcel Dekker New York, 1968. 

Gielen, M., and N. Sprecher, Organometallic Chem. Rev., 1966,1, 455 (adducts of organo compounds of Group IV). 

The present first volume of the series deals with symmetrical GeR4 compounds (Section 1.1.1) and a portion of the GeRgR compounds (Section 1.1.2), namely Ge(CH3)3R up to R = cycloalkyl. The literature has been covered to December 5, 1985 through the Chemical Abstracts on-line data retrieval service. A few papers where the original was unavailable and the abstract proved inadequate have not been included. The patent literature, far less numerous than for organo derivatives of the other Main Group IV elements, has been included in those cases where the abstract was adequate. 

Organometallic compounds (s. a. under individual metals. Group III element. . ., Group IV —. . ., Group V —. . ., Metal carbonyls. Metal complex compounds, organo-. Reagents, organometallic)... 

From 1971 to 1974 a group of Indian chemists published a series of papers in which the synthesis and the properties of more than 60 organo-Ce(IV) derivatives were described, including cyclopentadienyl, indenyl, fluorenyl, cycloheptatrienyl and cyclooctatetraenyl complexes (Table XLL). The structure of compounds was confirmed in the most cases by the data of elemental analysis (C, H, Ce), IR spectroscopy and chemical reactions. At the same time several attempts to repeat the described synthesis, which have been undertaken by other chemists, have failed, which gives the base for some doubts in reliability of the data of Kapur and coworkers. These reasons impelled us to collect all compounds of Ce(IV) described by the mentioned authors in a separate chapter. 

Various Ziegler-Natta and ROMP caalysts based on group IV-VIII transition metal salts showed to be very active and selective in the polymerization of both exo-and ew(7o-dicyclopentadiene [151-155]. Thus, binary Ziegler-Natta systems derived from chromium, molybdenum, and tungsten halides associated with organo-aluminum compounds form addition and ring-opened polymers [Eq. (94)]. 

The effect of substituents on the thermal stability of catenated derivatives is worth noting stability increases in the sequence halide < organo. Significantly, the substituents which stabilize catenated compounds are not those which form the strongest bonds to the Group IV elements, but those which release electrons most readily. It is likely that the M—M bond energy in a derivative pC(8-)]3M(8- -)-M(8-t-)pC(8-)]3 is sensitive to the size of the positive charge 8- - on M, and if, as seems likely in many cases, fission of the M—M bond is a key step in their decomposition, the stability sequence is readily understood. 

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