Group IVB organometallics

Lappert, M. F., Simpson, J., Spalting, T. R., A Mass Spectrometric Study of Some Group IVB Organometallic Compounds Containing Metal-Metal Bonds, in George, W. O., Spectroscopic Methods in Organometallic Chemistry, Butterworths, London 1970, pp. 197/8. 

Compared with the other Group IVB organometallic halides, knowledge of organolead halides is somewhat sparse. 25,26,202. The types RsPbX and R2PbX2 are well characterized, but compounds of formula RPbXs are practically unknown. 

The fundamental Ziegler-Natta recipe consists of two components the halide or some other compound of a transition metal from among the group IVB to VIIIB elements and an organometallic compound of a representative metal from groups lA to IIIA. Some of the transition metal compounds that have been... 

Organometallic complexes containing Group IIIB and Group IVB ligands 115a... 

T. R. Crompton, Chemical Analysis of Organometallic Compounds. Volume 3. Elements of Group IVB, Academic Press, London, 1974, pp. 1-12. 

In general, a ZNC is a combination of a transition metal compound from Group IVB (4) to VIIIB (10) and an organometallic compound of a metal from Group lA (1) to IIIA (13) in the... 

A major limitation of such Group IVB metallocene catalysts is that they are air- and moisture-sensitive and not tolerant to heteroatom-containing monomers. In the case of heteroatom-containing monomers the unbonded electron pairs on the heteroatom, such as oxygen, preferentially coordinate to the Lewis acid metal center in place of the carbon-carbon double bond. Some so-called middle and late transition metal organometallics are more tolerant to the presence of such heteroatoms and can be used as effective cocatalysts. These include some palladium, iron, cobalt, and nickel initiators. 

The number of compounds and combinations of compounds that fit into the category of Ziegler-Natta catalysts are far too numerous to describe here. However, a Ziegler-Natta catalyst may be simply defined as a combination of two components (1) a transition metal compound of an element from groups IVB to VIIIB, and (2) an organometallic compound of a metal from groups I to III of the periodic table. The transition metal compound is referred to as the catalyst and the organometallic compound as the cocatalyst. A combination of the catalyst and the cocatalyst is often referred to simply as the catalyst. 

Organometallic polyethers are formed utilizing low T condensation and addition systems " . Group-IVA and -B polymetalethers are synthesized utilizing nonaqueous interfacial systems and group-IVB polymetalethers are synthesized employing classical and inverse interfacial systems and aqueous solution systems ... 

Recently, groups experienced in Group IVB chemistry started research programs with the objective to study Group IIIB organometallic chemistry in relation both to early transition metals and f-elements. Thompson and Bercaw recently published their results on Cp ScR compounds [33]. Our work on Cp YR chemistry will be reported in the following section. In relation to this, relevant literature data on organo-yttrium chemisty will be mentioned first. 

Drager, M., Organometallic Compounds with Homonuclear and Heteronuclear Group IVB-Group IVB (Silicon Group) Bonds, Comments Inorg. Chem. 5 [1986] 201/14. 

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