Reactions between Clusters

In a computation of the kind of clustering reactions, between molecules you need the positions of the atoms for each ligand, that is the distances and the angles (and even that you can nowadays optimize if you wish). That is one input the other input is the basis set, namely the linear combination of atomic orbitals in terms of which you decide to develop your molecular orbitals. Now this is not an empirical parameter, it is a choice you decide that you ate going to express your molecular orbitals as a linear combination of a certain set of... 

Most of these reactions have only been examined with Fe3(CO)i2, but recently studies of the reactions of Rus(C0)i2 and Os3(CO)i2 with thiols have been made. Many of these reactions lead to degradation of the cluster. Reactions between Group VI compounds and metal carbonyl compounds have been reviewed (2). 

The reaction between a trinuclear metal carbonyl cluster and trimetbyl amine borane has been investigated (41) and here the cluster anion functions as a Lewis base toward the boron atom, forming a B—O covalent bond (see Carbonyls). Molecular orbital calculations, supported by stmctural characterization, show that coordination of the amine borane causes small changes in the trinuclear framework. 

The main synthetic route to high nuclearity metal carbonyl clusters involves a condensation process (/) a reaction induced by coordinatively unsaturated species or (2) a reaction between coordinatively saturated species in different oxidation states. As an example of (/), Os2(CO)22 can be condensed to form a series of higher coordinated species (89). 

Indium clusters have also recently been characterized, notably in intermetallic compounds. Thus, the Zintl phase, Rbzinj, (prepared by direct reaction between the two metals at I530°C) has layers of octahedral closo-lnf, clusters joined into sheets through exo bonds at four coplanar vertices. These four In atoms are therefore each bonded to five neighbouring In atoms at the comers of a square-based pyramid, whereas the remaining two (Irans) In atoms in the Ine cluster... 

The solvothermal reaction between metal halides and polysulfide anions is also a useful method for the synthesis of metal-polysulfide clusters. Hydrothermal reaction of K2PtCl4 with K2S4 (5 eq) at 130 °C in a sealed tube... 

Reactions between tantalum cluster ions Espenson and McCarley have estimated the rate coefficient for the reaction Ta6Clt +Ta6Cl 2 = 2 TagCl ... 

In the second cluster, the two Ru6 octahedra are linked through two palladium atoms. The third cluster contains two additional palladium atoms. The Pd4 skeleton adopts the form of a bent square. The two Ru6 octahedra have local structures similar to those in the second cluster, but their relative orientation is now twisted. Apparently, formation of these heterometallic cluster complexes does not result from a simple combination reaction between cationic and anionic complexes but is accompanied by partial redox reactions.900... 

In 1996 Stack and co-workers reported an unusual 3 1 (copper 02 stoichiometry) reaction between a mononuclear copper(I) complex of a A-permethylated (lR,2R)-cyclohexanediamine ligand with dioxygen. The end product of this reaction, stable at only low temperatures (X-ray structure at —40 °C) is a discrete, mixed-valence trinuclear copper cluster (1), with two Cu11 and a Cu111 center (Cu-Cu 2.641 and 2.704 A).27 Its spectroscopic and magnetic behavior were also investigated in detail. The relevance of this synthetic complex to the reduction of 02 at the trinuclear active sites of multicopper oxidases4-8 was discussed. Once formed, it exhibits moderate thermal stability, decomposed by a non-first-order process in about 3h at —10 °C. In the presence of trace water, the major isolated product was the bis(/i-hydroxo)dicopper(II) dimer (2). 

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