Isolobal 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). 

How many different neutral square-pyramidal cluster compounds can you synthesize on paper using the isolobal principle, the cluster electron-counting rules, and SiH and CpRh fragments only. 

The types of mixed p-block-d-block clusters that follow the isolobal principle and cluster electron-counting rules can be organized and compared in several different ways. Variables are cluster size and shape and main-group and transition-element... 

It was first demonstrated in exploratory work by the groups of Dahl, Ginsburg, " Sacconi and Huttner that elemental phosphorus can play a role as a ligand for transition metals. These early contributions were followed by extremely successful systematic studies by Scherer and his collaborators, the results of which have been summarized in several review articles. The work was also put into perspective referring to the isolobal principle (CH/P) and to cluster theories. ... 

The existence of mixed metal-boron clusters constitutes one example of the validity of the isolobal principles when applied to a class of compounds. The stoichiometric and structural diversity of metallaboranes is truly striking, and the idea of isolobal fragments combined with the electron counting rules is sufficient to rationalize this diversity—this fact is impressive (67,68,69, 70, 71, 72, 73, 74). We have explored the mixing of boron and metal characters in cluster MOs in the Bs nHg-nlFeCCOla) ] nido cluster series (Fig. 5). Examples of the first four members of this series (a, b, c, and d) have been well characterized (75, 76, 77), and suggestive evidence has been published for a B2H6RU3-... 

Chapter 23 The isolobal principle and application of Wade s rules 715... 

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 ... 

Isolobal principle between a CHj elemental hydride and a d metal complex. 

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