Iron family metals cobalt

What oxidation states are exhibited by the platinum metals— analogues of the iron family elements In what are they similar to iron, cobalt, and nickel ... 

The lacunar cyclidene ligands are the first family of totally synthetic ligands to form both iron(II) and cobalt(II) Oj carriers. The molecular structure of the lacunar cyclidene complexes is most simply represented by the flat projection (la), while the stereochemistry is shown in Ib. Cyclidene refers to the parent macrocycle encircling the metal ion and the lacuna is the permanent void created by bridging the cleft arising from the saddle shape of the cyclidene macrocycle. 

This family includes alloys based on transition metals, such as nickel, iron, cobalt, and palladium. ... 

Likewise, the designation of groups as A" or B is purely arbitrary. Assignment of all of the transition metals to B,r groups has an internal consistency as well as historical precedent.20 Unfortunately, some periodic charts have used A and B in an almost opposite sense.21 In addition, as a historical carryover from the older "short form chart, the iron, cobalt, and nickel families were lumped under the nondescript Vlir. This state of confusion led the 1UPAC to recommend that the groups... 

The pattern we have seen in the immediately preceding elements continues with iron and its congeners—the metal and +2 oxidation state are reducing, the higher oxidation states are oxidizing species. Members of the cobalt and nickel families, however, tend to be stable only in the +2 oxidation state unless stabilized by complexation. The reader may readily apply the methods illustrated previously to examine tbe relative stability of the individual oxidation states. 

Mercury-transition metal bonds have been described for all members of Groups V-VIII of the transition series except, apparently, technetium. They commonly involve a low oxidation state of the transition element and are particularly numerous for the chromium, iron and cobalt families.1 In addition, mercury-titanium bonded species have been postulated as unstable reaction intermediates.2... 

The bleomycins (Fig. 12.6) are a family of glycopeptide-derived antibiotics which are used in the treatment of various tumors. They bind iron in the blood and form an active hypervalent oxo-iron species. The two-dimensional structure is well known but no crystal structures of bleomycin or its metal complexes have been reported. The MM2 force field was modified and extended by modeling of the crystal structures of the cobalt complexes of two bleomycin analogues in order to develop a force field for... 

Elements observed in this activity (copper, iron, cobalt, nickel, zinc, sodium, magnesium, calcium, bromine, and iodine) belong in the following families alkali metals, alkaline earth metals, transition metals and halogens. Place each element in its proper family. Is there any relationship between the element s family and the element s color ... 

In Group VIII, each position instead of being filled by a single element is occupied by a group of three elements. Thus there appear in triads iron, cobalt, and nickel ruthenium, rhodium, and palladium and osmium, iridium, and platinum. In this group there is no subdivision into families, but all the members are heavy metals. 

Cobalt(II) has a special place in the open framework family because it is one of the few transition metal cations that easily exhibits tetrahedral coordination, in addition to five and sixfold ones. Moreover, magnetic couplings can give rise to interesting magnetic properties, similar to those described above for iron. Furthermore, it is well known that Co doping enhances the catalytic performance of certain zeolites and related compounds. For instance, CoAPO-5 and CoAPO-11 have been used for the autoxidation of cyclohexane [77] and p-cresol [78]. 

The inclusion of the six transition metal ions — cobalt, copper, iron, manganese, molybdenum, and zinc — in Table 1.1 is no coincidence — we saw earlier that they are essential trace elements for man. So, together with the 11 bulk elements, we have now identified 17 of the essential elements. Their relative positions in the Periodic Table are shown in Fig. 1.3, which presents the first six rows of the Periodic Table, colour-coded into families. Zn has ligand-binding constants intermediate between those of Mg and Ca " and those of the group of five other transition metals. Unlike them, zinc effectively does not have access to any other oxidation state than Zn (the +1 state compounds are very unstable). Zn not only plays a structural role, but can also fulfil a very important function as a Lewis acid (Chapter 12). 

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