Triorganosilicon acetylacetonates. Enol ether isomerism and stereochemical lability

Abstract

empirical least-squares treatment of Figure 4 to be 97, 97, and 94°, respectively, while the observed values are 94, 92, and 92°. The Pd-bridge Cl bonds opposite the olefinic groups are 0.1 A longer than the Pd-Cl bond lengths in (PdCl2)". However, the ring angles in all three palladium compounds are the same. This observation can be rationalized by invoking the "trans" effect and requiring the palladium orbitals to be highly directional in character. This can be contrasted to the Ni2Cl84_ anion with a "well-behaved" Ni-Cl-Ni angle of 99.1 °. GaCl3 has a Ga-Cl-Ga angle approximately 5°less than that predicted by the Ga-Cl distance of 2.29 Á. Dahl33 has pointed out that one of the factors leading to anomalously acute bridge angles is metalmetal bonding, and perhaps this is the case in GaCl3.

Carbonotropy

“…Silylotropy of acetylacetone derivatives [14] can be readily achieved requiring fairly low activation energy for the 0, 0' -transfers of the trialkylsilyl group. On the other hand, substitution of this group by an alkyl migrant in O-alkyl derivatives of analogous structure does not lead to (2.4) type tautomerism 1.;/ .…”

The Problem Of Tautomerism

“…Tautomeric system (1.17) is an example of unsymmetrical double-well potential in metallotropic migration. Degenerate silylotropy of acetylacetone derivatives belongs to this type [100] ,¥ H,CVCH, 1.5b.…”

The Mechanisms of Nucleophilic Substitution at the Main Group Elements and Design of Intramolecular Tautomeric Systems

“…In the pure form, the tautomeric 1,5-silyl migrations were first detected in the series of the acetylacetone cis-enols XXVII (R = CH 3 , Rl = R2 = R3 = CH 3 ) [58].…”