Organometallic compounds of Ga, In and

Organometallic compounds of Ga, In and Tl have been less studied than their Al analogues. The trialkyls do not dimerize and there is a general tendency to diminishing thermal stability with increasing atomic weight of, M. There is also 

The triphenyl analogues are also monomeric in solution but tend to associate into chain structures in the crystalline state as a result of weak interraolecular M---C interactions GaPhr mp 

InPhj mp 208°, TlPhj mp 170°. For Ga and In compounds the primary M-C bonds can be cleaved by HX, X2 or MX3 to give reactive halogen-bridged dimers (R2MX)2. This contrasts with the unreactive ionic compounds of T1 mentioned above, which can be prepared by suitable Grignard reactions  

As in the case of organoaluminium compounds, unusual stereochemistries can be imposed by suitable design of ligands. Thus, reaction of GaCh with 3,3, 3 -nitrilotris(propylmagnesium 

SCHMIDBAUR, R. Hager, B. Huber and G. Muller, Angew. Chem. Int. Edn. Engl. 26, 338-40 (1987). See also H. SCHMIDBAUR, W. Bublak, B. Huber and G. Muller, Organometallics 5, 1647-51 (1986). 

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Many organoaluminium compounds are known which contain 1, 2, 3 or 4 Al-C bonds per A1 atom and, as these have an extensive reaction chemistry of considerable industrial importance, they will be considered before the organometallic compounds of Ga, In and T1 are discussed. 

Since 1980, interest in organometallic compounds of Ga, In and T1 has grown, mainly because of their potential use as precursors to semiconducting materials such as GaAs and InP. Volatile compounds can be used in the growth of thin films by MOCVD metal organic chemical vapour deposition) or MOVPE metal organic vapour phase epitaxy)... 

As mentioned above, ion pairs in the gas phase may be considered as examples of coordination number 1. There are a few other examples known. For instance, the aryl radical derived from the highly stencally hindered 1,3,5-triphenylbenzene, forms one-to-one2 organometallic compounds of the type and AgC HjlC Hsls. 

Three main topics relevant to the gas-phase chemistry of Ge, Sn and Pb derivatives are discussed in the present chapter (a) the mass spectrometry related to organometallic compounds of group 14 with particular emphasis on the more general aspects (b) the gas-phase ion chemistry comprising the thermochemistry, structure and reactivity of ions and (c) gas-phase reactions involving neutral species. 

All heavy crude oil residues have heavy metals such as Ni, V or Fe in their structure. These metals are bonded as organometalic compounds. At high temperatures and for hydrogenation reactions, these compounds are cracked and heavy metals are deposited on the catalyst surface. These metals can also react with hydrogen sulfur from the gas phase to form metal sulfides. The deposition of sulfides of iron, vanadium or nickel leads to irreversible poisoning of the catalyst. This is the difference between catalyst deactivation by metals and deactivation by coke the former leads to an irreversible loss of the catalyst activity. 

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