Clusters mixed

B. Influence of Solvation on the Composition of Protonated Clusters Mixed Cluster Systems... 

In all three mixed cluster ions systems, the intensity distributions show94 that there is a maximum at n + m = 5. Results of metastable decomposition studies95 of the mixed cluster ions were determined to be ... 

Experiments made at higher degrees of aggregation have provided strong evidence192 for ring-like structures for mixed neutral clusters. For example, under a wide variety of experimental conditions, mixed cluster ions display a maximum intensity atm = 2(n + 1) whenn<5 for (NH3)II (M)mH+, andm = n + 2 whenn<4 for (H20)B(M)mH+ M is a proton acceptor such as acetone, pyridine, and trimethy-lamine. These findings reveal that the cluster ions with these compositions have stable solvation shell structures as discussed above. 

In other related studies,186 we determined the structures of mixed water-methanol clusters the intensity distributions of (H20)n(CH30H)JBH+ showed magic numbers at n + m = 21, 0 < m 8 due to the enhanced stabilities of the dodecahedral cage structures in the mixed clusters. Studies of the metastable dissociation of (H20)B(CH30H)mH+ (n + m < 40) provided evidence that the dissociation channels... 

An important aspect of studying metastable dissociation of these clusters is that the measurements enable a determination of the surface composition of mixed systems. This is important in designing experiments to study the heterogeneous chemistry of aqueous systems. For example, the loss channel of H20 is found to be open to all (H20)n(CH30H)mH+ except (H20)(CH3OH)mH+ for which the water loss is relatively small. For the water-rich composition mixed clusters, the results show that water molecules have a tendency to build a cage structure in the cluster size region m + n = 21, with 0 < m < 8. 

The same strategy as for the synthesis of 40 has been employed for the preparation of the Li/Sn-mixed cluster 41. Thus, replacement of the imido groups in [Sn(NtBu)]4 with LiPHR (R = cyclohexyl) in the molar ratio of 4 6 yielded the metallacyclic cage complex 41, which has a rhombododecahedral Li4Sn4P6 core (Eq. 24) (69). The clusters 40 and 41 are isostructural, since the MeAl fragments in 40 have been replaced by the isoelectronic Sn(II) centers. 

Mixed clusters NH3/H20 (139-141), NH3/MeOH (61), and NH3/Me2CO (142) have been reacted with bare metal ions and in general the transition metal ions preferred coordination to ammonia whereas the non-transition metal ions such as Mg+ and Al+ were nonselective, showing some similarity to condensed-phase systems. 

Iron, cobalt and nickel Number of M-M bonds Idealized symmetry M-M in mixed clusters... 

Because of the large number of carbonyl groups required to satisfy the noble gas rule and the relatively small metallic radius, serious steric limitations are present for manganese tetranuclear closed clusters12). The only known tetranuclear compounds are some mixed clusters, MnOs3(CO)16H and MnOs3(CO)13H3 (see later), which have been prepared from Os3(CO)12 and [Mn(CO)s] 161). 

There are several examples of mixed clusters which are homologous with the dode-cacarbonyls. Some of these compounds, such as the anion [FeCo3(CO)i2] and the neutral cyclopentadienyl carbonyl Co3Ni(CO)9Cp, are believed to be iso-structural with Co4(CO)j2 and it is therefore convenient to discuss these compounds now. 

XIII. Clusters of Ni, Pd, Pt and Mixed Clusters Containing Group VIII C Metals... 

When mixed clusters of alcohols are formed, the issue of donor acceptor isomerism comes into play [58]. Both alcohols can act as donors and acceptors, but the difference between their donor (2d) and acceptor (2a) qualities (2d 2a) will not be the same. The molecule that features the smaller... 

The development of the synthesis concept described here for metalloid clusters should ultimately be capable of extension to element combinations and therefore molecular nanostructured alloys, as several results on metalloid SiAl and SiGa clusters have shown [114, 88, respectively]. Such mixed clusters resemble the Zintl-type compounds that are under intense investigation by Corbett et al. [115, 124-126],... 

In the latter case each 14-electron CpCo group completes its valence-shell by sharing electron pairs with one other CpCO group and with three phosphorus atoms, consistent with its diamagnetic character and with the observed geometry. It is likely that many more such mixed clusters, incorporating both transition metals and main group element, will be developed in the future. 

A rather obvious means of Incorporating the electron-poorer elements from groups earlier In the periodic table Into clusters Is then to combine them with electron-rlcher elements. Some results of synthetic and structural Investigations of this sort Involving Ions with 2.2 - 3e per cluster element are listed In Table II together with data for three electron-rlcher mixed cluster anions. 

Unusual mixed cluster compounds of the type [RuPt2(CO)5L3] and [Ru2Pt(CO),U] (L = PPh3, PMePh2, PMejPh, or AsPh3 = PMejPh) have been prepared via the addition of Ru3(CO)j2 to PtC. The structures (2) and (3) were proposed from i.r. studies. These clusters join a growing number... 

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