Group II oxides

Synthetic routes to metalloboranes are briefly summarized. Two specific aspects of the field are selected for more detailed comment (i) the occurrence of exopolyhedral cycloboronation of P-phenyl groups (ii) oxidative cluster closure reactions. These topics are illustrated by reference to reactions of closo-BioHio nido-B9H12 and arachno-BoHiU" with a variety of Ir1 complexes, and several novel metalloborane cluster geometries (as determined by X-ray diffraction analysis) are described, notably nido-TIr(BoHi )H (PPh3)2], i so-ni do-[ IrC(OH)B8H6(OMe) (CgH PPh )... 

Group II oxides, C-Sm203 and C-EU2O3. In the first case, additional hydration does occur, so that, as shown in [30], the hydroxycarbonate phase coexists with Nd(OH>3. For the remaining two oxides, no hydroxide could be detected [55,106],... 

The first type of organic polyradicals is composed of an unconjugated backbone bearing highly stable radicals in its side chains. Such macromolecules can be synthesized from (i) the preparation and subsequent polymerization of a radical monomer containing a vinyl group, (ii) oxidation or reduction of a precursor macromolecule and (iii) introduction of a radical unit to a macromolecular backbone through a polymer reaction. For the example of (i), poly(4-methacryloyloxy-... 

All Group IV elements form both a monoxide, MO, and a dioxide, MO2. The stability of the monoxide increases with atomic weight of the Group IV elements from silicon to lead, and lead(II) oxide, PbO, is the most stable oxide of lead. The monoxide becomes more basic as the atomic mass of the Group IV elements increases, but no oxide in this Group is truly basic and even lead(II) oxide is amphoteric. Carbon monoxide has unusual properties and emphasises the different properties of the group head element and its compounds. 

Lead(II) oxide is the most basic oxide formed by a Group IV element. It dissolves easily in acids to give lead(II) salts but it also dissolves slowly in alkalis to give hydroxoplumbates(II) and must, therefore, be classed as an amphoteric oxide, for example ... 

Tandem cyclization/3-substitution can be achieved starting with o-(trifluoro-acetamido)phenylacetylenes. Cyclization and coupling with cycloalkenyl trif-lates can be done with Pd(PPh3)4 as the catalyst[9]. The Pd presumably cycles between the (0) and (II) oxidation levels by oxidative addition with the triflate and the reductive elimination which completes the 3-alkenylation. The N-protecting group is removed by solvolysis under the reaction conditions, 3-Aryl groups can also be introduced using aryl iodides[9]. 

The commonly used commercial lead-based PVC stabilizers rely on one or more lead(II) oxide groups bound to the primary bivalent lead salt. 

Hydrazino groups are also converted into H-compounds with mercury(II) oxide (74CR(C)-(278)427) in other reactions they have given hydrazones, or have been converted into pyrazoles and fused heterocyclic rings (77JAP(K)7785194), e.g. (72) -> (73). 

Again, as with pyridopyrimidines, the main reaction is oxidation of di- or poly-hydro derivatives to fully aromatic structures, often merely by air or oxygen. In some cases the reagent of choice is mercury(II) oxide, whilst other reagents used include sulfur, bromine, chloranil, chromium trioxide-acetic acid, hydrogen peroxide, and potassium ferricyanide, which also caused oxidative removal of a benzyl group in the transformation (306) (307)... 

Although both aluminum and indium are in Group 13/III, aluminum forms A1J+ ions, whereas indium forms both In3+ and In+ ions. The tendency to form ions two units lower in charge than expected from the group number is called the inert-pair effect. Another example of the inert-pair effect is found in Group 14/IV tin forms tin(IV) oxide when heated in air, but the heavier lead atom loses only its two p-electrons and forms lead(II) oxide. Tin(II) oxide can be prepared, but it is readily oxidized to tin(IV) oxide (Fig. 1.56). Lead exhibits the inert-pair effect more strongly than tin. 

Begin by writing a balanced equation. Remember that all Group II carbonates decompose to yield the metallic oxide plus carbon dioxide gas. 

Variation of Bond Energy with Oxidation State of Group II, III, and IV... 

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