Posttransition metals

C20-0113. On Earth, two posttransition metals, A1 and Pb, are used when low- and high-density metals are desired. Suppose you are transported to a planet elsewhere in our galaxy, where all transition metals are readily available but posttransition metals are rare. Where among the transition metals would you seek a replacement for A1 for low-density uses, and where would you seek a replacement for Pb for high-density uses Explain your reasoning. 

The solution complexation behavior of manganese(II) and selected other transition and posttransition metal ions with 1-carboxymethyl-1,4,7-triazacyclononane has been investigated by potentiometric titration, with the stabilities of the 1 1 complexes found to follow the usual Irving-Williams stability order. " ... 

Finally, the heavier posttransition metals have group number oxidation states corresponding to < 10 configurations indium(lll), thallium(III), tin(IV), lead(lV), anti-mony(V). bismuth(V), etc. However, there is an increasing tendency, termed the inert pair effect," for the metals to employ p electrons only and thus to exhibit oxidation states two less than those given above (see Chapter 18). 

Among the heavier posttransition metals there is a definite reluctance to exhibit the highest possible oxidation state. Thus in Group IVA (14), tin has a stable +2 oxidation slate in addition to +4. and for lead the +2 oxidation state is for more important Other examples are stable Tl+ (Group II1A, 13) and Bp+ (Group VA, 15). These oxidation states correspond to the loss of the np electrons and the retention of the ns electrons as an inert pair .30... 

Porterfield. W. W., 295 Positive oxidation states, halogens in, 837-848 Posttransition metals, 28. 876 Potassium, 309, 582-587 Potentials, electrode, 378-383 Pourbaix diagram, 591-592 Praseo complex, 388,491, 493 Predominance area diagram, 591 Prewitt, C. T., 116-117 Principal axis, 51 Prism, trigonal prism, 489-491 Probability function, 13 Prosthetic group, 919 Proteins, and blue copper proteins, 912-916 Proton... 

Decomposition of formic acid on transition and posttransition metal surfaces has drawn a great deal of interest in recent years (121-137). The process shows distinct periodic regularities and, therefore, is well suited for the BOC-MP analysis. We want to understand the mechanism of HCOOH decomposition, in particular (1) why formate HCOO is the prevailing intermediate, (2) what is the preferred coordination mode, V or t)2, for HCOO, and (3) how HCOO decomposes further into C02 and CO. 

Studies of UV-vis spectra suggest that several bis-8-hydroxyquinoline-substi-tuted aza-crown ethers are potential chemosensors for Cu2+. As shown in Figure 8, addition of Cu2+ to an aqueous acetate-buffered solution of a tetraaza-15-crown-5 ligand functionalized with two 8-hydroxyquinoline groups (102) leads to a new peak at 258 nm which develops gradually.155 The other transition and posttransition metal ions, Co2+, Ni2+, Zn2+, Cd2+, Hg2+, Pb2+, and Ag+ (only Zn2+, Cd2+, and Pb2+... 

The molecular structure of [Hg(CO)2][Sb2Fn]2, the first example of a thermally stable carbonyl derivative of a posttransition metal, has also recently been reported. The [Hg(CO)2l + cation is nearly linear, with the Hg-C-0 bond angle of 177.7(7)°. However, the coordination environment around the mercury atom is that of a distorted octahedron due to weak Hg- -F interactions producing an extended two-dimensional structure where each anion links a pair of cations and each cation links four anions. 

Heterometallic alkoxides of calcium, strontium, and barium with transition or posttransition metals have been formed by reactions with the preformed alkoxides (e.g., Table 8, Equations (8a) and (8b)). A variation on this approach generates the Group 2 alkoxides in situ by reaction of the metal with an alcohol and/or another alkoxide (e.g.. Table 8, Equations (9a) and (9b)). " " ... 

Main group elements Lighter transition and Heavier transition and and lanthanides posttransition metals posttronsition metols... 

Configuration exhibited by the posttransition metals in their highest oxidation states (Gat 111). 

I Note that these same criticisms apply equally well to scandium (known only as the Sc ", ion). 19 That is. there would be only thirteen lanthanides and actinides, just as elimination of zinc, cadmium, and mercury leaves only nine transition metal groups, and elimination of the noble ga.ses. leaves only five groups to contain the nonmetals and posttransition metals. The main difficulty with any of these suggestions is that they contradict the simple expectations that the j-block should consist of two elements, the p-block should consist of six elements, the d-block should consist of ten elements, and the /-block should consist of fourteen elements. 

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