Heteronuclear clusters metals

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). 

In addition to the heteronuclear clusters considered in the preceding paragraphs. As, Sb and Bi also form homonuclear clusters. We have already seen that alkaline earth phosphides M3P14 contain the [Pv] cluster isoelectronic and isostructural with P4S3, and the analogous clusters [Asy] " and [Sbv] have also been synthesized. Thus, when As was heated with metallic Ba at 800° C, black lustrous prisms of BasAs were obtained, isotypic with Ba3Pi4 these contained the [Asv] anion with dimensions as shown in Fig. 13.25(a).Again,... 

Pignolet, L. H. Krogstad, D. A. The Heteronuclear Cluster Chemistry of the Group 11 Metals—Some Recent Advances. In Gold, Progress in Chemistry, Biochemistry and Technology Schmidbaur, H., Ed. Wiley Chichester, U.K., 1999, pp 429-493. 

A further point of interest is their ready interconversion in solution, which we have studied by variable temperature n.m.r. measurements (8). Reaction of [(n-C5H5)(0C)2W =CR] with polynuclear metal carbonyl species is likely to afford many new heteronuclear cluster compounds containing tungsten. 

More recently, Adams and coworkers have provided a very interesting case of heteronuclear clusters that are very active for the hydrogenation of alkynes [4, 54, 55]. The high-nuclearity layer-segregated Pt-Ru complex [Pt3Ru6(CO)21(jU3-H)(/ -H)j], consisting of three stacked triangular layers of metal atoms with an... 

Outside this chapter on general aspects of structure, bonding, syntheses, and reactivities the material will be presented according to the position of the metals in the periodic table. For heteronuclear clusters the compounds will be treated as belonging to the metal later in the periodic table. Compounds mentioned in this review without giving a reference have been dealt with in former reviews. 

The phosphine-substituted cluster Re4(CO)io(PMePh2)5 resulted from Re2(CO)jQ and the ligand under u.v, irradiation 296. Pi. rare example of a sulfur atom bridging four metal atoms is present in the heteronuclear cluster [JJ] prepared from [(CO)4Re-S-SnMe3]2 and Cp(CO)3MoCl(J5J). 

The square face of cluster 5 is readily capped by a number of different metal fragments affording octahedral heteronuclear clusters in high yield. The dianion 5 reacts with the Group 6 complexes M(CO)3L3 (M = Cr,... 

Heteronuclear Clusters Containing Platinum and the Metals of the Iron, Cobalt, and Nickel Triads... 

The subject of heteronuclear cluster compounds of the transition metals remains an active area of research interest, and was reviewed in the early 1980s by Geoffroy el al. (1,2). Clusters with novel architectures, exemplified by the star clusters of Stone and co-workers (5), continue to be synthesized. Whereas there is undoubtedly strong academic interest in the structure, bonding, and chemical reactivity of heteronuclear clusters in their own right, additional impetus to this field is given by the important relationship between heteronuclear clusters and bimetallic alloy catalysts. This relationship was the subject of a published symposium (4). 

The addition of transition metal fragments ML (L = two-electron donor ligand) across formally unsaturated metal-metal or metal-carbon bonds is a well-developed synthetic route to heteronuclear clusters (1,2,11,12,27) and has received theoretical justification from Hoffmann s isolobal principle (46). The addition of a PtL2 fragment across an M=M double bond may be considered as analogous to the reaction of a carbene with an olefin, resulting in a cyclopropane. The use of isolobal analogies in the directed synthesis of heteronuclear clusters has been reviewed (11,12,27). 

Addition of Co2(CO)8 to the //2-vinylidene complex (40) (Section IV,A,6) affords the heteronuclear cluster derivative (88) in 55% yield, in which the vinylidene group now bridges all four metal atoms ... 

Summary of Metal-Metal Bond Lengths for Au Heteronuclear Cluster Compounds Containing Terminal AuPR3 Fragments... 

Summary of Bond Lengths and Metal Cage Geometries for Au, Heteronuclear Cluster Compounds Containing p.2-AuPR3 Fragments... 

Reaction of the rhenium hydride complex ReH7(PR3)2 (where R = Ph or p-tol) with Au(PPh3)N03 has yielded the heteronuclear cluster compounds [Au5Re(H)4(PR3)2(PPh3)5](PF6)2 (148) in which the metal cores are based on edge-shared bitetrahedra with the rhenium atom at one of the two most-connected vertices. This is illustrated in Fig. 24. A... 

The heteronuclear clusters described previously also conform to this generalization, as Tables XVI and XVII demonstrate. All of the clusters characterized by 12ns + 16 valence electrons adopt toroidal geometries and will readily add one molecule of carbon monoxide to give clusters with a valence electron count of 12ns + 18. The resultant metal cage geometries have been described as either spherical or hemispherical. 

The Group IB metal site preferences in heteronuclear cluster compound allow coinage metal exchange reactions between clusters and mononuclear complexes to be used as a high yield synthetic route to novel trimetallic species containing two different Group IB metals. These reactions are discussed in detail in Section II,D,2. 

Although the vast majority of Group IB metal heteronuclear clusters have been synthesized using one of the generally applicable rational preparative procedures outlined in Sections II,A,1 and II,A,2, a number of such species have been obtained via routes for which the nature of the product cannot be predicted in advance or via procedures which have not been widely used. These other methods of synthesis are outlined in this section. 

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