Heteronuclear clusters mixed

As most of the heteronuclear clusters of tin and lead actually involve these two elements specifically, we present the results on these mixed clusters in the same section. 

In the chemistry of hexanuclear metal clusters the coexistence of mixed-charge cluster units within homo- and heteronuclear clusters is possible. The synthetic routes have been identified and include ... 

Among large metal clusters there are also some heteronuclear or mixed-metal clusters that have been mentioned as metal-alloy clusters . The bimetallic Au-Ag clusters (p-Tol3P)i2Aui8Ag2oCli4 and [(p-Tol3P)i2Aui8Agi9Brn], whose metal frameworks are illustrated in Fig. 2.39, belong to this class. A very... 

The red tetrathiomolybdate ion appears to be a principal participant in the biological Cu—Mo antagonism and is reactive toward other transition-metal ions to produce a wide variety of heteronuclear transition-metal sulfide complexes and clusters (13,14). For example, tetrathiomolybdate serves as a bidentate ligand for Co, forming Co(MoSTetrathiomolybdates and their mixed metal complexes are of interest as catalyst precursors for the hydrotreating of petroleum (qv) (15) and the hydroHquefaction of coal (see Coal conversion processes) (16). The intermediate forms MoOS Mo02S 2> MoO S have also been prepared (17). 

Electric fleld gradient, 22 214-218 Electroabsorption spectroscopy, 41 279 class II mixed-valence complexes, 41 289, 291, 294-297 [j(jl-pyz)]=+, 41 294, 296 Electrocatalytic reduction, nickel(n) macro-cyclic complexes, 44 119-121 Electrochemical interconversions, heteronuclear gold cluster compounds, 39 338-339 Electrochemical oxidation, of iron triazenide complexes, 30 21 Electrochemical properties fullerene adducts, 44 19-21, 33-34 nickeljll) macrocyclic complexes, 44 112-113... 

Mercury(II) forms a series of compounds in which it is bonded to a transition metal to form heteronuclear Hg—M bonds.540,541 The most widely used synthetic routes have been reviewed elsewhere.542-549 Besides heteronuclear bonds M—Hg there are structural elements M—Hg— M, 550 e.g. (31), or cyclic arrangements as in Os3(CO)uHg 3415 or (1/5-MeC5H4)Mn(CO)2Hg 4.416 A trigonal prismatic coordination of mercury has been reported in the green zerovalent mixed metal cluster [Hg Pt(2,6-Me2C6H3NC)fi ]. a... 

It is possible to synthesize mixed-metal clusters containing Au(PR3) fragments by treating neutral as well as anionic precursors with either [Au(PR3)]+ or a compound that acts as a source of this cation. In many cases, a [Au(PR3)]+ unit is simply added to the cluster precursor to afford a cationic heteronuclear gold cluster (e.g., 59,62-66). Equation (27)... 

The action of hydrogen or oxygen on heteronuclear gold clusters has been used to afford species of higher nuclearity [Eqs. (43)—(45)] (72,83,84). Mixed-metal gold clusters of lower nuclearity have been... 

A homonuclear gold cluster has been used as a precursor to a heteronuclear species in which two gold atoms are bonded to Co(CO)4 fragments [Eq. (55)] (90). Treatment of the cluster salt K[Co3Fe(CO)12] with [Bu"N][AuI2] also affords a mixed-metal cluster containing a Au Co-(CO)4 unit [Eq. (56)] (91). 

As is the case for transition metal cluster compounds in general, singlecrystal X-ray diffraction is normally the only technique available for the unambiguous structural characterization of heteronuclear Group IB metal clusters. Tables I, II, and IV-XIV indicate the mixed-metal clusters containing one or more ML (M = Cu, Ag, or Au L = two-electron donor ligand) units which have been studied by X-ray crystallography. Other... 

Another technique that has recently proved to be very useful for facilitating the characterization of heteronuclear Group IB metal cluster compounds is fast atom bombardment (FAB) mass spectrometry. Although the mass spectra of some mixed-metal clusters containing ML units have... 

Heteronuclear M—M Bonds. The transition metals, especially in their carbonyl-type compounds, form many bonds to the non-transitional metal or metalloidal atoms. This is particularly true for the elements Zn, Cd, Hg, Cu, Ag, Au, Tl, Ge, Sn and Pb. These are nearly always 2c-2e bonds which require no special comment. However, there are cases where mixed metal clusters of a more complex nature are formed. Examples of these are trigonal-bipyramidal Sn2Pt3 species and tetrahedral Ge2Co2 species. 

Heteropolyatomic Zintl anions like the polyhomoatomic ones may also exist in solution. Actually, many heteronuclear compounds, which are not obtained as crystalline species, possibly due to the same causes discussed above for the homonuclear species, may be studied in solution. Multinuclear NMR spectroscopy has proved to be an excellent technique for such studies. Mixed polyanions containing atoms of the same group can apparently be prepared in solution practically in any proportion within the normal nuclearity range of the homonuclear species by dissolving the appropriate ternary alloys. Thus for instance, from sodium-thin-lead alloys in ethylenediamine solution the following series of cluster anions [SnxPb9 x] may be stabilized. 

Heteronuclear compounds with an Fe-M bond have received much attention in the past decade. Significant progress has been made both in their synthetic methodologies and in the study of their chemical reactivity. There are more than 300 papers that have reported on the chemistry of this class of compounds, and more than 700 structurally characterized mixed-metal compounds that contain iron have appeared since this area was reviewed in COMC (1995). Clearly, this volume of data and information should be best presented in a systematic way, for which a tabulated form is preferable. All of the heterodinuclear species and mixed-metal clusters with known structures are therefore presented in Tables 1-3 respectively. 

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