Group 12 Zinc

Cadmium(II) and zinc(II) systems other than cyanides Among the i acceptors of the zinc group, the softness rapidly decreases from the markedly soft Hg2+ to the mildly soft Cd2+ and to the distinctly hard Zn2+. As mentioned above, only very soft ligands such as CN are coordinated to Cd2+ or Zn + by bonds which are essentially covalent. Nevertheless, covalent bonding is still important for the formation of the Cd2+ halide complexes. This is evident from the fact that the values of AHn become more exothermic as the halide becomes larger and consequently more polarizable and susceptible to covalent bonding. This trend results in the (6) or soft sequence for the halide systems of... 

The members of the d block, with the exception of the elements in Group 12 (the zinc group) are called transition metals. As we shall see, these elements are transitional in character between the vigorously reactive metals in the s block and the less reactive metals on the left of the p block. The members of the f block, which is shown below the main table (to save space), are the inner transition metals. The upper row of this block, following lanthanum (element 57) in Period 6, consists of the lanthanides and the lower row, following actinium (element 89) in Period 7, consists of the actinides. 

The entire series of alkali metal compounds (Me3Si)3SiM (M = Li, Na, K, Rb, Cs) have been prepared by Klinkhammer and coworkers via a metal-metal exchange reaction from bis[tris(trimethylsilyl)] derivatives of the zinc group, [(Me3Si)3Si]2M (M = Zn, Cd, Hg), and the corresponding alkali metal in -pentane or -heptane (equation 28)66a,b. 

Thiel W, Voityuk AA. Extension of MNDO to d orbitals parameters and results for the second-row elements and for the zinc group. J Phys Chem 1996 100 616-626. 

W. Thiel and A. A. Voityuk, /. Phys. Chem., 100, 616 (1996). Extension of MNDO to d Orbitals Parameters and Results for the Second-Row Elements and for the Zinc Group. 

Perchlorate Frequencies of Zinc Group Metal Complexes... 

Each of the zinc group elements has two electrons beyond a pseudo-rare-gas structure, that is, two electrons beyond a completed d subshell. 

The melting points, boiling points, and heats of vaporization for the zinc group members are lower than for any other group of metals except la. By the argument presented on page 99, one would expect these metals to have abnormally high" oxidation potentials that is, they should be less noble than other metals with comparable ionization potentials. Thus zinc (ionization potential 9.39 volts) is more easily oxidized than iron (ionization potential 7.90 olts), cadmium (ionization potential 8.9S volts) is more easily oxidized than nickel (ionization potential 7.63 volts), and mercury (ionization potential 10.43 volts) more easily than platinum (ionization potential 8.88 volts). Note that the ionization potentials would favor the opposite order in each case. 

The abundances of the elements of the titanium group were compared to those of the zinc group in Table 13-1. It will be recalled that unlike the zinc group metals, which are rare but easily isolated, the titanium group metals are abundant, but purified with difficulty. Note from the (very rough) figures given that titanium is 50 times as abundant as zinc, zirconium is 3000 times as abundant as cadmium, and hafnium 30 times as abundant as mercury. 

These also decrease rapidly in the order Cu+ > Ag+ > Au+, reflecting the slower and slower rate of decrease of CBE along the halide series with increasing softness of the acceptor. For H+, a very reasonable intermediate value is found. The pattern is very similar for the divalent ions. High values are found for the alkaline earths, and low values for the ions of the zinc group, the latter ones decreasing in the order Zn2f > > Cd2+ > Hg2+, while the transition metal ions are in an intermediate position, as expected. 

Zinc Group.—Zinc phosphides have been made chiefly by reactions (1) and (2) (p. 60). Molten zinc unites readily with phosphorus.1 A compound Zn3P2 was prepared by the action of phosphorus vapour on zinc dust 2 the zinc oxide present was reduced and also gave phosphide.3 The phosphide was a grey, well-crystallised substance which did not mix with molten zinc. It was sublimable in hydrogen over 1000° C. and when heated in the air oxidised to zinc phosphate.4 It was not attacked by water, but acids gave phosphine and zinc salts.5 The hydrophosphide, obtained by the action of phosphine on zinc ethide in ether cooled with ice and salt, is much less stable. It is a white powder which is at once decomposed by cold water giving phosphine and zinc hydroxide.6... 

Precipitated phosphates of the zinc group and of the alkaline earth metals and magnesium dissolve in acetic acid, whereas those of iron, aluminium and chromium remain undissolved, a fact which is much used in qualitative analysis. The hydrion concentrations, expressed as pH, at which the various precipitates appear have been determined.5 All phosphates dissolve in excess of dilute strong acids, in many cases only that amount of acid being required which will convert the precipitate into a primary or dihydrogen phosphate (cf. CaH4(P04)2, p. 222). 

H.A. Tajmir-Riahi, Carbohydrate adducts with zinc group metal ions. Interaction of p-D-fructose with Zn(ll), Cd(ll) and Hg(II) cations and the effects of metal-ion coordination on the sugar isomer binding. Carbohydr. Res., 172(198) 1. 

Absorption of d-limonene by the different sealant films during storage at 24°C, 49 RH is shown in Table 3- Within 3 days storage, all of the films had rapidly absorbed d-limonene. After 3 days, the rate of absorption in LDPE and Surlyn (sodium type) decreased, while Surlyn (zinc type) had reached saturation. 12 and 18 days were required to reach saturation for Surlyn (sodium type) and LDPE respectively. Thg amount of d-limonene absorbed at equilibrium was 6.4 mg/100 cm for Surlyn (zinc type). The carboxy and zinc groups in the Surlyn probably alter the lipophilic character of the polymer, but do not prevent absorption of flavor components. 

---