Mercury halides, complexes with

We begin by considering the stability constants for the formation of halide complexes with zinc(ii) and mercury(ii) (Table 9-2)... 

The structures of two ruthenocene-mercury halide complexes have been reported at an early stage of refinement (2 >0.22), The complex [(ii-C5H5)2Ru]HgBr2 is dimeric (15) with distorted tetrahedral co-ordination... 

Zinc, cadmium and mercury are at the end of the transition series and have electron configurations ndw(n + l)s2 with filled d shells. They do not form any compound in which the d shell is other than full (unlike the metals Cu, Ag and Au of the preceding group) these metals therefore do not show the variable valence which is one of the characteristics of the transition metals. In this respect these metals are regarded as non-transition elements. They show, however, some resemblance to the d-metals for instance in their ability to form complexes (with NH3, amines, cyanide, halide ions, etc.). 

The X-ray crystal structures of the related, though less complex, anticrown mercury-containing macrocycles 45 and 46 have also recently been reported. Complex 45 may form either 1 1 complexes with Br or I" or a 3 2 complex with Cr. In the case of the bromo derivative, crystallographic results reveal an infinite chain of alternating Br and 45 with each halide bridging between six Hg atoms, Hg- Br 3.07-3.39 A. It is postulated that the related 3 2 chloride complex exhibits a similar, though finite layered structure. The related pentameric species 46 forms... 

Rubidium metal alloys with the other alkali metals, the alkaline-earth metals, antimony, bismuth, gold, and mercury. Rubidium forms double halide salts with antimony, bismuth, cadmium, cobalt, copper, iron, lead, manganese, mercury, nickel, thorium, and zinc. These complexes are generally water insoluble and not hygroscopic. The soluble rubidium compounds are acetate, bromide, carbonate, chloride, chromate, fluoride, formate, hydroxide, iodide,... 

Ligand exchange reactions have been used to prepare mercury(II) trialkylarsine complexes.202 Reaction of AgN03-AsMe3 with mercury halides gave the mercury arsine and silver halide (equations 10 and 11). The silver nitrate complex was not characterized. 

Metal complexes of several zinc, cadmium and mercury salts with 2-, 3- and 4-cyanopyridine have been reported.495 In none of the complexes was cyanide coordination observed. Zinc halides react with 3- and 4-cyanopyridine, but not with 2-cyanopyridine, to give 1 2 complexes which are assigned a monomeric tetrahedral structure on the basis of IR evidence. The cadmium halides also form 1 2 complexes with all the cyanopyridines, except cadmium chloride, which reacts with 2-cyanopyridine to give a 1 1 complex. The former contain... 

Both 1 1 and 2 1 complexes of Af,.ZV-diethyl- and N,iV-dimethyl-thiourea with zinc, cadmium and mercury halides have been prepared. The 2 1 complexes are either monomeric and tetrahedral or polymeric and halogen-bridged with octahedral metal coordination the 1 1 complexes also possess a polymeric, halogen-bridged structure, but with tetrahedral metal coordination.894 5... 

The reaction of dithiooxamide and its tetramethyl and tetraethyl derivatives with zinc, cadmium and mercury halides leads to complexes of stoichiometry MLX2 (M = Zn, Cd or Hg X = C1, Br or I).900,9 1 M—S bonding is involved IR spectra show that the zinc and mercury complexes are four-coordinate, while the cadmium complexes are octahedral with halogen bridges. 

The stability constants in melts of NH4N03- H20 of ZnX+, ZnX2 (n = 1-3 X = Cl or Br), CdX+, CdX2 (n = 1.5-3 X = Cl or Br) and HgX HgX2 (n = 2.5 X = Cl or Br) have been determined.950,931 The behaviour of zinc is peculiar if the Ki and K2 values are compared with those of cadmium and mercury. The stability constants increase with temperature and the bromide is more stable than the chloride, trends which are opposite to those normally observed for the halide complexes of most metals in anhydrous or aqueous melts. The data also show... 

Tri(f-butyl)phosphine and tri(o-tolyl)phosphine form 1 1 complexes with mercury(II) halides and with Hg(SCN)2. Physicochemical measurements, Le. conductance, molecular weight determinations, IR and Raman spectra, indicate a dimeric structure (26) of Cy, skeletal symmetry.493... 

Following the preparation of 4.79, a number of other cyclic mercury crown compounds have been synthesised, which do exhibit halide complexation behaviour. Compound 4.80, forms a 1 1 polymer with bromide in the solid state in which the Hr anions perch above the Hg3 plane. The Hg—Br distances of 3.07-3.39A are considerably longer than normal Hg—Br covalent bonds (about 2.54A).61 The compound also binds SCN- with similarly long bonds as shown in Figure 4.34.60 The analogous chloride complex has a 3 2 stoichiometry suggesting a triple-decker sandwich of type [4.80 Cl 4.80 Cl 4.80]2. ... 

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