Transition metal cluster chemistry

Developments in transition metal cluster chemistry — the way to large clusters. G, Schmid, Struct. Bonding (Berlin), 1985,62, 51 (132). 

Schmelcher PS, Cederbaum LS (1996) Two Interacting Charged Particles in Strong Static Fields A Variety of Two-Body Phenomena. 86 27-62 Schmid G (1985) Developments in Transition Metal Cluster Chemistry. The Way to Large Clusters. 62 51-85... 

Schmid, G. Developments in Transition Metal Cluster Chemistry. The Way to Large Clusters. Vol. 62, pp. 51-85. 

Gas phase transition metal cluster chemistry lies along critical connecting paths between different fields of chemistry and physics. For example, from the physicist s point of view, studies of clusters as they grow into metals will present new tests of the theory of metals. Questions like How itinerant are the bonding electrons in these systems and Is there a metal to non-metal phase transition as a function of size are frequently addressed. On the other hand from a chemist point of view very similar questions are asked but using different terminology How localized is the surface chemical bond and What is the difference between surface chemistry and small cluster chemistry Cluster science is filling the void between these different perspectives with a new set of materials and measurements of physical and chemical properties. 

The field of gas-phase transition metal cluster chemistry has expanded rapidly due to the development of the laser vaporization source and the fast flow chemical reactor. The work from the three major laboratories have been reviewed. Many additional laboratories are developing cluster chemistry programs and will soon certainly make significant contributions. 

Removal of two vertices from a deltahedron leads to arachno polyhedra having 2n + 6 skeletal electrons according to the Wade-Mingos rules [13-16]. Among the many theoretical possibilities for arachno polyhedra, the pentagonal antiprism, generated by removal of a pair of antipodal vertices from an icosahedron, is the most significant in bare post-transition metal cluster chemistry. 

In the last section of this review, we elaborated on the relevance and consequences of these concepts for transition-metal cluster chemistry on the basis of new results. We discussed problems and pitfalls that may arise in present-day quantum chemical DFT calculations on open-shell clusters. Clearly, these obstacles point to the necessity of developing improved density functionals and also new ab initio electron correlation methods, like, for example, the density renormalization group algorithm (151). 

The political justification for transition metal cluster chemistry is the assumption that clusters are models in which metallic properties may be more easily studied than in the metals themselves. These properties include electronic phenomena such as color and conductivities as well as surface phenomena, such as atom arrangements and catalytic activities. Thus, there are two main lines of cluster research. The more academic line leads to the search for new types of clusters and their structure and bonding, whereas the more practical line leads to the investigation of reactivities with the hope that clusters may open catalytic pathways that neither plain metals nor mononuclear catalysts can provide. The interdependence of both lines is obvious. 

Considerable advances in the field of transition metal cluster chemistry have been made during the last five years. They have confirmed that in many respects a cluster complex is comparable to a metallic surface. They have also shown that clusters allow reactions which are not observed with simple metal complexes. And they have finally demonstrated that structural and bonding properties of clusters require new concepts for their description. 

J.-X. Lu (ed.), Some New Aspects of Transitional-Metal Cluster Chemistry, Science Press, Beijing/New York, 2000. 

Whitmire, K. H. The interface of main group and transition metal cluster chemistry, J. Coord. Chem. B 1988,17, 95. 

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