Derivatives of Group IV Elements

Little is known about valence-shell expansion reactions among still higher row elements, but the considerable oxidative stability of silicones and of tetraalkyl derivatives of group IV elements suggests that valence shell-expansion doesn t provide an easy path for oxygen attack in this group. 

Table 15. Election diffraction data on oxygen derivatives of group IV elements...

Vaickus, M. J., Anderson, D. G., Investigation of Phenyl Derivatives of Group IV Elements Using Carbon-13 NMR Spectroscopy, Org. Magn. Resonance 14 [1980] 278/9. 

The experimental conditions are not specified precisely with respect to the presence of oxygen. This point is particularly important for a mechanistic interpretation due to the role of oxygen traces in the occurrence of an ET process in related reductions.The procedure was extended to the reduction of halo and alkoxy derivatives of Group IV elements, in apolar solvents instead of ethers. Deuteration can be carried out with lithium aluminum deuteride in perdeutero-cyclohexane. 75 The time shortening brought about by sonication in the reduction of veratraldehyde by tributyltin hydride on silica gel was mentioned but not exploited.Little if any effect was noted in the reduction of various aroyl... 

Fig. 1.2 Mean bond dissociation enthalpies in methyl, ethyl and phenyl derivatives of Group IV elements at 298.15 K.

Chemical Shifts and Coupling Constants of Derivatives of Group IV Elements (8 in ppm relative to TMS, / in Hz)... 

Indeed separate experiments showed that lithium iodide reacts both with tin tetrachloride and with germanium tetrachloride, so that perfluoro-n-propyllithium made via the lithium-sodium alloy cannot be used to prepare (n-C3F7)4Sn and (n-C3F7)4Ge. Nevertheless, it is now established that perfluoro-re-propyllithium may be used to synthesize a number of new perfluoropropyl derivatives of Group IV elements, and probably similar compounds of other elements as well (9). As a result it is likely that perfluoro-alkyllithium compoimds will play a more important part in synthetic work in the future than they have in the past. 

Several cyclopentadienyl derivatives of Group IV elements have long been known to behave as fluxional molecules. Now F n.m.r. spectroscopy of P(A -C5H5)F2 shows that this Group V derivative is also a fluxional molecule. No quantitative kinetic data were quoted, but a qualitative impression can be... 

The ambident phosphorothioate anion (122) yields O-metalloidal derivatives when treated with chlorides of Group IV elements.92... 

Thiophene derivatives of group IV,B elements 82MI32, 82SR(2)177. Thiophene derivatives as intermediates in organic synthesis 86CRV795 ... 

Quinoline derivatives of group IV,B elements 86MI6, 86MI7. 

The principal valence of Group IV elements is 4, each element of the group except lead forming its principal series of compounds in the quadrivalent state. Valences of 2 are common, and 3 occasional. The quadrivalent halogen compounds of most of the elements form characteristic double derivatives with the alkali halides, of the type M12MlTX. These compounds, especially the fluorides, are of much importance. 

Bis(trifluoromethyl)mercury is useful in the preparation of numerous CF3 derivatives, especially of group IV elements. It was first prepared in 1949 by irradiation of CF3I and Hg in the presence of Cd. Alternative routes include radiofrequency discharge methods, for example, reaction of CF3 radicals witli HgXz or elemental mercury. Preparative scale quantities are best obtained by decarboxylation of mercury trifluoroacetate in the presence of carbonate. ... 

Neumann, W. P., Recent Developments in the Field of Organic Derivatives of Group IV B Elements, Pure Appl. Chem. 23 [1970] 433/46. 

This discovery was exploited by Lukevics et al. [7], providing a route to the hydrides of a number of group IV element derivatives from the corresponding halo, alkoxy and amino compounds. The reaction is completely dependent on sonication and does not occur in its absence (Scheme 113). 

Many of the applications of group IV element NMR are relatively straightforward from a spectroscopic point of view and are therefore not discussed here. Worthy of special note, however, are Si studies of aqueous silicates and silicones, molten silicates, and silyl transition metal derivatives the use of Si/ H 2D correlation spectra to make assignments and the substantial and growing body of body of Si MAS and/or CP work on solid materials such as zeolites, other silicate minerals, polysilanes, and surface-immobilized materials. The potential of solid-state NMR for Sn and Pb has yet to be fully realised, although solid trimethyl stannyl hydroxide and tributyl stannyl fluoride have been studied. 

The transition metal-group IV metal bond can be formed both by attack of a transition metal anion at a group IVg halide and by attack of an alkali metal derivative of the group IV element at a suitable transition metal complex. 

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