Isolobal analogy principle

The addition of transition metal fragments ML (L = two-electron donor ligand) across formally unsaturated metal-metal or metal-carbon bonds is a well-developed synthetic route to heteronuclear clusters (1,2,11,12,27) and has received theoretical justification from Hoffmann s isolobal principle (46). The addition of a PtL2 fragment across an M=M double bond may be considered as analogous to the reaction of a carbene with an olefin, resulting in a cyclopropane. The use of isolobal analogies in the directed synthesis of heteronuclear clusters has been reviewed (11,12,27). 

The isolobal analogy [9,10] tells us that this n + 1)-SEP rule can be in principle extended to any type of closo skeleton made of fragments possessing a similar set of 3 FOs (see Fig. 1), irrespectively of their energy and precise shape or composition. This is indeed the case of many transition-metal carbonyl or phosphine organome-tallic clusters, most of them built from conical ML3 fragments. For example, the three octahedral clusters [BeHe], [Ru6(CO)ig] [46], and [Ru4(CO)i2Bi2] [47] are 7-SEP species. ... 

Hoffmann s isolobal analogy is a general unifying principle that goes far beyond the confines of cluster chemistry. Nevertheless it has found most... 

Hoffmann s isolobal analogy is a unifying principle that identifies analogies between organic and inorganic structures in terms of their bonding pattern. Different L M groups are considered isolobal with... 

Using the isolobal principle, one can relate clusters that contain fragments having analogous orbital properties. Some isolobal pairs of metal carbonyl and hydrocarbon fragments are ... 

Certain L M fragments are often considered carbene-like because there is an analogy between their insertion into X—Y bonds and the insertion of an organic carbene, such as CH2, into a C—H, Si—H, or O—H bond (Eq. 3.17). In Section 13.2, we will see how the isolobal principle allows us to understand the orbital analogy between the two systems. There are several mechanisms... 

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