Electron count versus structural arrangement in clusters based on a cubic transition metal core with bridging main group elements

Abstract

The bonding of diverse molecular clusters based on a cubic transition metal core with bridging main group elements is reviewed. It is shown that the cluster topology of these compounds is dependent on several parameters which can be calibrated. A large range of electron counts is generally observed without alteration of the cubic architecture. Examination of their electronic structures indicates that these species are at the borderline between molecular and solid states, characterized either by a closed-shell electronic configuration secured by a significant HOMO-LUMO gap, or by a quasi-continuous energy level structure often associated with open-shell electronic configurations.

Bonding Analysis of Inorganic Transition-Metal Cubic Clusters. 6. Copper(I)−Dithiolato Species and Related Compounds

“…Examples of transition-metal cubic clusters encapsulating an additional metal atom are well-documented . Since the reported experimental Cu···Cu distances of the title compounds lie in the range 2.6−3.1 Å (Tables and ), it is possible to speculate about a centered cubic arrangement in which both types of Cu···Cu separations would lie in this range.…”

“…The absence of any significant Jahn−Teller distortion away from T h symmetry is likely to be due to its very high connectivity. This situation is reminiscent of solid-state chemistry and of other highly connected clusters . This electron deficiency is even larger in the related 284-MVE species Pd 20 As 12 (PPh 3 ) 12 ( 9 ), in which the metal oxidation state is +1.8.…”

“…Although cubic transition-metal clusters are far less common than octahedral clusters, they are nowadays well documented in the literature . Investigations of the electronic structure of some of them by us and by others have contributed to a rationalization of their bonding and an understanding of their stability and properties.…”

“…Another reason for our interest in these compounds is that some of them have been shown to incorporate an encapsulated main-group atom (see Table ), as exemplified by Cu 8 [S 2 P(O i Pr) 2 ] 6 (μ 8 -S) ( 2 ), made by Fackler and co-workers 9a. We were interested in comparing the nature of the bonding between the Cu 8 cage and its host with that of other atom-centered cubic clusters which we have analyzed previously. ,2b,e Moreover, we were also interested in investigating theoretically the possibility of incorporating transition-metal atoms, as observed in other examples of cubic clusters …”

Different Ways To Distort a Tetracapped Tetrahedron on Route to Forming an E4M4 Cubane: The Case of [E4(Pd(PPh2Me)2)4][Ph2EX2]2 (E = Sb, X = Cl; E = Bi, X = Br)

“…Especially numerous are group 13−16 (III−VI) cubane molecules. − Perhaps the most famous class of cubane structure is that in which A is a transition metal fragment ( M ) and B is a main group element functionality ( E ). These fragments may be either “naked” or bear a substituent such as an alkyl or aryl group. − Regular homonuclear cubes of the transition metals are also known, but they have only been found to exist with ligands bridging the square faces or edges and may also possess interstitial atoms. − …”