Halides of Silicon, Germanium, Tin, and Lead

Hensen, M. Achatz, and R. Mtiller, Theor. Chim. Acta, 1973, 28, 297. 

Joklik and V. Bazant, Coll. Czech. Chem. Comm., 1972, 37, 3772. 

Rathousky, O. Kruchna, and J. Joklik, Chem. prumysl, 1972, 22, 485 Chem. Abs. 

The direct reaction between chloromethylsilanes and Cu-Ge couples at 360—400 has been employed by Mironov and Gar to prepare several 

The reactions of a-chloromethyl ethers ROCH2CI (R = Me, Et, or Bu) with powdered tin at 20—80 °C afford low yields of the dihalides (ROCH2)2-SnCIg. Dimethyltin dichloride may be prepared in 75—80 % yield by heating tin with methyl chloride in hexamethylphosphoramide at 140—150 C. Silicon tetrabromide is obtained by bromination of pure or commercial silicon, or ferrosilicon, in the presence of Cu, CuBr, or CuBr2 at 350—600 °C. Optimum yields are obtained at 500 C. A 97 % yield of germanium tetrachloride is obtained when vitreous germanium dioxide is treated with 

Germanium(iv) bromide has been reinvestigated by electron diffraction. Constraining the molecule symmetry to afforded a value of 2.272(1) The electronic radial distribution functions for germanium(iv) and tin(iv) chlorides in the liquid state at 23 °C have been calculated from X-ray diffraction intensity distributions obtained by use of theta-theta reflection diffractometry. Both liquids show intermolecular effects at distances equivalent to the Cl—Cl intermolecular distance. Values of 0.9 D (Si—Cl), 1.5 D (Ge—Cl), and 2.7 D (Sn—Cl) have been derived for the bond dipole moments of these bonds in the metal(iv) 

Zeldin, D. Solan, and B. Dickman, J. Inorg. Nuclear Chem., 1975, 37, 25. 

5-dichloro-l,4,6,5-oxathiametallocans (X = 0) (57). Solutions of these compounds contain two chiral boat-chair conformers with are equilibrated by passing 

Grobe and J. Hendriock, Synth. React. Inorg. Metal.-Org. Chem., 1975, 5, 393. 

Bellama and J. A. Morrison, Inorg. Nuclear Chem. Letters, 1975, 11, 127. 

---

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... 

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 ... 

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. 

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... 

Of all the reactions studied, only the synthesis of nitrogen oxides and acetylene in arcs or plasma torches and that of ozone in glow and corona discharges are of major importance. In addition, a few small-scale preparations of inorganic compounds have been developed, e.g. synthesis of hydrazine and of hydrides and halides of silicon, germanium, tin, lead, phosphorus or arsenic 3> ... 

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. 

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. 

The metal-nonmetal line passes through the heart of the group, with carbon being a bona fide nonmetal and lead a bona fide metal. In between are two metalloids (silicon and germanium) and a borderline metal (tin). The progression in the acid-base character of the oxides of the elements further emphasizes the trend from nonmetal to metal. The formulas of the oxides and halides show the increasing importance of the +2 oxidation state down the group, and this is reinforced by a consideration of standard reduction potentials. 

---