Agostic complex

One of the most defining characteristics of the late metal a-diimine polymerization systems is the uniquely branched polyolefins that they afford. This arises from facile p-hydride elimination that late transition metal alkyl complexes undergo. The characteristics of the isomerization process have been the subject of much investigation, particularly with the more easily studied Pd(II) a-diimine system. The process is initiated by P-hydride elimination from the unsaturated alkyl agostic complex 1.17, followed by hydride reinsertion into olefin hydride intermediate 1.18 in a non-regioselective manner (Scheme 5). In doing so, the metal center may migrate... 

Scheme 6 a Isomerization of 3-agostic propyl complexes 1.19 and 1.20. b Isomerization and trapping by ethylene of tert-butyl complex 1.22, showing unfavorability of ethylene complexation to 3° agostic complexes... 

Complexation of HC C-EHs (E is C, Si, or Ge) to Ni and Cu differs from the alkene complexation in that conventional 7i-complexes are the global minima for all the elements However, when E = Si or Ge, the agostic complexes... 

So far, the only example of a saturated carbon bridge in a Si-H-M p-agostic complex is found in the Ru complex 58, prepared by an interesting reaction of... 

It is obvious that studying interligand Si-H interactions has reached a great extent of sophistication. At least three classes of nonclassical Si-H bonding can be identified. These are the electron-deficient residual Si H interactions in silane a-complexes and agostic complexes, electron-rich IHI MH SiX, and the more recent multicenter H Si interactions, which are the subject of current debate and have features common to both IHI and a-complexes. This surprising diversity stems from the special role the substituent at silicon can play in tuning the extent of Si H interaction, and from the propensity of silicon to be hypervalent. 

Aerobic microbial biomethylation, antimony, 12, 644 AFM, see Atomic force microscopy Aggregation, gas-phase study applications, 1, 803—804 Agostic complexes... 

Mononuclear ruthenium compounds acyl complexes, 6, 398 agostic complexes, 6, 392 alkenyl complexes... 

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