Halides group 14 metals

The bonding mode is dependent on the nature of the metal centre as well as the steric or electronic properties of the imido substituent. For example, the M(CO)5 unit in the (AO-trigonal complex [W(CO)5 S(NMe)2 ] undergoes a 1,3-shift between the two nitrogen donors, whereas the tert-butyl forms a N,N -chelated [W(CO)4 S(NtBu)2 ] complex, as is also observed with main-group metal halides, e.g., [SnCl4 E(NtBu)2 ] (E=S, Se).153... 

The volatile, air-sensitive liquid species (CH3)2A1B3H8 and (CH3)2GaB3Hg are prepared by the direct reaction of the corresponding main group metal halide and salts of the [B3H8] ion, in the absence of solvent (178). The reaction of (CH3)2A1B3H8 and Al(BH4)3 results in the species (BH4)2A1B3H8. These small metallaboranes are fluxional in solution and have limited thermal stability at room temperature. 

Recent efforts involving these systems include (i) high-pressure studies and structural phase transformation stabilization of mixed valence main group metal halides (iii) synthesis of low oxidation state halides and (iv) characterization of mixed metal halides. 

In the set of main group metal halides, we could readily systematize the solid-state examples according to group number. Since, in general, several oxidation states are observable for each transition metal, it is more convenient to discuss these halides according to their empirical formulas,... 

Information about the binary main group metal halides abounds in numerous texts and tabulations.Table 2 gives a qualitative listing of many of the halide stoichiometries adopted by the main group metals. All solid-state compounds tend to behave as salts with very low electrical conductivity. Many of the pure compounds with metals in their higher... 

Main group metal halides T1CI4 + 2H2O T1O2 (H20) -I- 4HC1... 

Such compounds are usually obtained by reaction of titanium group metal halides with Mg(allyl)X ... 

Main group metal halides TiCh -1- 2H2O Ti02 (H20) h- 4HQ... 

Main group metal halide fragments coordinated to transition metals are prone to attack by sodium carbonylmetallates. Firfiray, Irving and Moss have shown that [Os3Cl(SnCl3)(CO)i2] reacts with Na[M(CO)3Cp] (M = Mo, W) by sutetitution at tin, Eq. 5.22 ... 

The most common route to cyclic carbonates is the reaction of epoxides with CO2, which is promoted by a variety of homogeneous, heterogeneous and supported catalysts either cyclic carbonates or polymers are obtained [89]. Main group metal halides [90a] and metal complexes [90b], ammonium salts [91] and supported bases [92], phosphines [93], transition metal systems [88, 94], metal oxides [95], and ionic liquids [96] have been shown to afford monomeric carbonates. A1 porphyrin complexes [97] and Zn salts [89, 94, 98] copolymerize olefins and CO2. 

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