Group mixed-metal clusters

Photoelectron spectroscopy has been used to determine the threshold of electron detachment in small cluster anions and in some cases electronic transitions may be observed. The group of Nakajima and co-workers (261-264) studied several metal sulfide cluster anions. Many other systems have been studied by photoelectron spectroscopy including the [LaCJ (265), [AuC6F6] (266), and mixed-metal cluster anions (267). 

Although no distinct differences are found for the Mo—Mo distances in the mixed-metal clusters except for 5, short (1,2,3, and 8), and long (6, 7, 9, and 10) Mo—M distances are observed. The first group has transition elements M in the cores, whereas the second group has nontransition elements M in the cores. The Mo—Cu distances in 3 and 8 are slightly longer than those of Mo—Fe and Mo—Ni in 1 and 2, respectively. 

Independent discovery of the silylformylation of alkynes was reported by the Matsuda and Ojima groups. The general reaction involves addition of both CO and tertiary hydrosilane to an alkyne to yield silyl alkenals, catalyzed by rhodium or rhodium-cobalt mixed metal clusters [Eq. (46)]. 

Imido dialkyl complexes, with tantalum, 5, 120 Imido-dicarbenes, with palladium, 8, 228-229 Imido groups, in Ru-Os mixed-metal clusters, 6, 1078 Imido hydrocarbyl complexes, with Re(VII), 5, 945 Imido ligands... 

The photophysical and photochemical reactivity of the mixed metal cluster, [Os2Ru(CO)io(iPrAcPy)], was also examined by this group. Their observation is that zwitterionic products are formed preferentially for the complex... 

It is clear that silicate units derive very significant proportion of their resonances from the [N(C2H5)4]+ countercation species. This implies that counteraction is located at the silica surface. Moreover, chemical shift of Q4 species correlates with the protons of the -CH3 group of the counter-cation species rather than with the Q3 or Q2 indicating that upon deposition of the mixed-metal cluster the contercation is embedded in the porous walls of the support.21... 

Fig. 1. Edge-bridging (a) and face-capping (b) bonding modes adopted by M(PR3) (M = Cu, Ag, or Au R = alkyl or aryl) units in mixed-metal clusters. M is a transition metal other than a Group IB metal.

Mixed-Metal Clusters Containing Two Face-Capping ML (M = Cu, Ag, or Au L = Two-Electron Donor Ligand) Units, with No Close Contact BETWEEN THE GROUP IB METALS... 

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... 

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