Structure cluster complexes

Figure 13.24 Structure of the cubane-like mixed metal-metal cluster complex [Sb4- Co(CO)3l4].

Pyrazole and [Os3(CO)io(AN)2] form two isomeric cluster complexes 90 and 91 (82IC634 84POL1175), corresponding to metallation of both basic nitrogen atoms (the major product having the symmetrical structure 90) and C,N-metallation... 

Electronic structures of transition metal cluster complexes. M. C. Manning and W. C. Trogler, Coord. Chem. Rev., 1981, 38, 89-138 (406). 

The electronic structure of transition metal cluster complexes with weak- and strong-field ligands. G. P. Kostikova and D. V. Korol kov, Russ. Chem. Rev. (Engl. Transl.), 1985,54, 344 (137). 

The exploratory solid-state synthetic work of John Corbett has illustrated the diversity, beauty and richness of this chemistry with a large variety of new phases and structures [1-3]. John Corbett was also the pioneer who recognized the potential of these cluster polymers in the development of a versatile solution chemistry [4]. Once the cluster unit has been identified in the solid state, the excision of this motif appears as the most rational method for accessing these cluster complexes in solution [5]. 

Synthesis and Structure of Molecular M3Q4 and M3Q7 Cluster Complexes 107 7.2... 

Fig. 15. The structures of some molybdenum and tungsten cluster complexes.

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... 

Many carbonyl and carbonyl metallate complexes of the second and third row, in low oxidation states, are basic in nature and, for this reason, adequate intermediates for the formation of metal— metal bonds of a donor-acceptor nature. Furthermore, the structural similarity and isolobal relationship between the proton and group 11 cations has lead to the synthesis of a high number of cluster complexes with silver—metal bonds.1534"1535 Thus, silver(I) binds to ruthenium,15 1556 osmium,1557-1560 rhodium,1561,1562 iron,1563-1572 cobalt,1573 chromium, molybdenum, or tungsten,1574-1576 rhe-nium, niobium or tantalum, or nickel. Some examples are shown in Figure 17. 

The information available is discussed in light of the effects of excitation energy and the environment on the photofragmentation process of several transition metal cluster complexes. The photochemical information provides a data base directly relevant to electronic structure theories currently used to understand and predict properties of transition metal complexes (1,18,19). 

It has been several decades since oxo-centered triruthenium-carboxylate complexes with triangular cluster frameworks of Ru3(p3-0)(p-00CR)6 (R = alkyl or aryl) were first isolated [1,2]. In the early 1970s, the first oxo-centered triruthenium complex was structurally characterized by Cotton through X-ray crystal structural determination [3]. Since then, oxo-centered trinuclear ruthenium-carboxylate cluster complexes with general formula [Ru30(00CR)6(L)2L ]n+ (R = aryl or alkyl, L and... 

The parent structure of the anion-deficient fluorite structure phases is the cubic fluorite structure (Fig. 4.7). As in the case of the anion-excess fluorite-related phases, diffraction patterns from typical samples reveals that the defect structure is complex, and the true defect structure is still far from resolved for even the most studied materials. For example, in one of the best known of these, yttria-stabilized zirconia, early studies were interpreted as suggesting that the anions around vacancies were displaced along < 111 > to form local clusters, rather as in the Willis 2 2 2 cluster described in the previous section, Recently, the structure has been described in terms of anion modulation (Section 4.10). In addition, simulations indicate that oxygen vacancies prefer to be located as second nearest neighbors to Y3+ dopant ions, to form triangular clusters (Fig. 4.11). Note that these suggestions are not... 

Fig. 25 The hydrogen bonded chain structure in complex [ Mo3S4(H20)7Cl2 2Hg](5)Cl4.14H20 where [ Mo3S4(H20)7Cl2 2Hg]4+ clusters are sandwiched between host 5 molecules [102]... 

The groups of Philipsborn [84], Heaton [85-88] and Mann [89-91] have used ° Rh NMR extensively to elucidate structural and mechanistic aspects of a wide variety of metal carbonyl and metal cluster complexes. Further, Zamaraevl [92] has shown that NMR studies on several quadrupolar nuclei, e. g. Mo, help with the characterization of the alkyl peroxo-complexes, which are thought to be inter-... 

Few examples are known for this type of intramolecular dihydrogen bond. One of them is the trimetallic osmium cluster shown in Structure 5.15 [28]. This compound, described well by various methods, has revealed a number of problems connected with characterizations of dihydrogen-bonded complexes that deserve separate discussion. The hydrogen atoms localized in the x-ray molecular structure of complex 1 of Figure 5.17 provide a formulation of interaction N-H -... 

Another method for calculating electronic structures of complex surfaces is the cluster calculation. As the electronic state of an atom is mostly affected by the nearest and second-nearest neighbors (Heine, 1980), the results of cluster calculations provide a reasonably accurate account of the electronic states of the top atoms on a surface. Fig. 4.17 is the result of a calculation of W clusters by Ohnishi and Tsukada (1989). 

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