Halides of germanium, tin and lead

Reaction between GeF2 and F gives [GeF3]. Several compounds of type MGeCl3 exist where M+ may be an alkali metal ion or a quaternary ammonium or phosphonium ion (e.g. equations 14.56 14.58). Crystal structure determinations for [BzEt3N][GeCl3] (Bz = benzyl) and 

The preference for the - -2 over the - -4 oxidation state increases down the group, the change being due to the 

As an interim measure, hydrochlorofluorocarbons (HCFCs) can be used in refrigerants in place of CFCs. While less harmful to the environment than CFCs, HCFCs are still ozone-depleting (they are classified as Class IT ozone-depleters) and will be phased out by 2020. Hydrofluorocarbons appear to have little or no ozone-depleting effect and can also be used in refrigerants and aerosol propellants. 

In the Antarctic winter, sunlight is absent. Once it returns in the spring (i.e. September), photolysis of CI2 results in the formation of chlorine radicals, C1 , and their presence initiates catalytic O3 destruction  

The CIO goes back into the cycle of reactions, and, from the five steps shown above, the overall reaction is  

There are many similarities between the tetrahahdes of Ge and Si, and 60X4 (X = F, Cl, Br or I) is prepared by direct combination of the elements. At 298 K, GeF4 is a colourless 

The Sn(IV) halides are Lewis acids, and their ability to accept halide ions (e.g. reaction 14.59) follows the order Snp4 SnCLt SnBr4 SnLj. 

Lead(II) chloride is much more soluble in hydrochloric acid than in water owing to the formation of [PbCm . In the solid state, PbCl2 has a complicated structure with 9-coordinate Pb centres, but Pbp2 adopts the fluorite structure (Fig. 6.19a). Yellow Pbl2 adopts the Cdl2 structure (Fig. 6.23). Discrete iodidoplumbate anions such as 

Worked example 14.5 Group 14 halides structure and energetics 

SnF4 sublimes at 978 K. Describe tbe changes that take place during sublimation and the processes that contribute to the enthalpy of sublimation. 

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Ruidisch, I., Schmidbaur, H. and Schumann, H., Organometallic halides of germanium, tin and lead," Halogen Chemistry 2j 233-3 9 V. Gutman, ed.. Academic Press, New York, London, 1967 ... 

Most of the complexes of germanium, tin, and lead in the IV oxidation state contain halide ions or donor ligands that are oxygen, nitrogen, sulfur, or phosphorus compounds. 

All Group IV elements form tetrachlorides, MX4, which are predominantly tetrahedral and covalent. Germanium, tin and lead also form dichlorides, these becoming increasingly ionic in character as the atomic weight of the Group IV element increases and the element becomes more metallic. Carbon and silicon form catenated halides which have properties similar to their tetrahalides. 

Bis(phosphino) and bis(arsino) derivatives of germanium, tin or lead are unknown. However, monophosphino- and monoarsino-germanium and tin halides, BU2EMX (M = Ge, Sn E = P, As, X = Cl, Br), have been characterized as thermally stable, though easily oxidized solids, which are thought to be highly associated.658-663... 

The reaction of the appropriate halides with diazomethane is an elegant laboratory-scale method for the synthesis of halomethyl derivatives of silicon, germanium, tin, and lead.1-4 However, good yields are obtained only with the following types ... 

In contrast to the sulfide of silicon (p. 187). the sulfides of tetravalent germanium (white) and tetravalent tin (yellow) are stable in water, but form complexes in the presence of excess sulfide ion. The sulfides of divalent tin and lead (both black) dissolve neither in strong base, in excess sulfide, nor in dilute acids. Note that PbS has the same structure as sodium chloride and is probably the most nearly covalent salt known having this structure, its color and metallic lustre setting it apart from the structurally similar ionic halides and oxides. 

Nucleophilic carbenes have been reported to react with Eewis acidic group 14 complexes with the isolation of neutral or ionic compounds via simple adduct formation or displacement of a halide ion. > The range of carbene complexes of silicon, germanium, tin, and lead, as well as some related cyclopropenylidene complexes are described below. 

Halides of Silicon, Germanium, Tin, and Lead.—Interest in halide derivatives has been focussed mainly on the synthesis of metal-halogen bonds, structure and bonding, and complex formation. A new method for the... 

Derivatives of Silicon, Germanium, Tin, and Lead containing Bonds to Transition Metals.— The substitution of organo-silicon, -germanium, -tin, and -lead halides... 

Thiol derivatives of silicon, germanium, tin and lead can readily be prepared from a halide, usually chloride, and a thiol in the presence of a hydrogen halide acceptor or a metal thiolate. Various illustrative examples... 

III. ORGANOMETALLIC HALIDES OF GERMANIUM(IV), TIN(IV) AND LEAD(IV) A. Organogermanium Halides... 

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