Neutral, Coordinatively Unsaturated Species

In contrast with 1.10.4.1, which deals with the oxidative addition of to neutral coordinatively unsaturated species, 1.10.4.3 describes the action of Hj with neu-... 

A coordinatively unsaturated species capable of adding RH can also be generated by extrusion from such neutral ligands as phosphine (Scheme IV.8) [17], carbon monoxide (Schmie IV.9) [18], olefin and, as well as, some other ligands (Scheme IV. 10) [19],... 

The intimate mechanism of the reaction deserves special attention not only because it was the first example of alkane activation by a metal complex. Activation of alkanes by platinum(II) complexes remains unique in many aspects. The reaction takes place in neutral water solution with conventional chloride ligands at the metal without special ways to form coordinatively unsaturated species (e.g., by irradiation). A number of works were directed towards the elucidation of the nature of the interaction between an alkane and a platinum(II) complex. The unique feature of platinum(II) complexes is to exhibit both nucleophilic and electrophilic properties. 

As coordinatively unsaturated species, four-electron donor stibinidenes and bismuthinidenes readily form adducts with neutral and anionic donors. The stabilizing effect of these interactions has been exploited to prepare otherwise unisolable pnictinidene complexes by addition of Lewis bases [227]. This Lewis base stabilization can also originate from a pendant donor group [30, 62, 233]. This last... 

Tricoordinated boron compounds (boranes) are coordinatively unsaturated and their chemistry is dominated by reactions in which complexes are formed. These complexes are either neutral molecules (borane complexes), anions (borates) or boron cations. Space limitations mean that little or no attention will be paid to complexes containing several boron atoms and to species of the type L-BH3, [BH,]- and [L2BH2]+ (L = neutral ligand), discussed in detail in several books and reviews. Similarly, little attention will be paid to the plethora of metal borates and the cyclic and polymeric amino- and phosphino-boranes. 

Some neutral metal carbonyls, particularly coordinatively unsaturated ones, are sufficiendy nucleophilic to undergo reaction with organic halides. Sigma-alkyl species which undergo subsequent CO insertion are formed by such reactions27. Hence, carbonylations... 

The condensation reactions of carbonyl metallates with neutral species, which are either coordinatively unsaturated or which will readily generate coordinatively unsaturated fragments, have also yielded a variety of mixed-metal clusters. The square-based pyramidal dianion [Fe5C(CO)i4] , for example, has been shown to react with a number of such species to yield octahedral FcjMC cluster compounds (Scheme 9) 269, 381). In some cases. 

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