ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
[Rh1(η5-azulene)(cod)]+BF4- complexes 3a-g (cod = (Z,Z)-cycloocta-1,5-diene) have been synthesized by reaction of [Rh1(cod)]+BF4- in THF with the corresponding azulenes 1a-g (Table 1). The structure of [Rh1(cod)(η5-guaiazulene)]+BF4- (3a) has been determined by X-ray diffraction analysis (Fig. 1 and 2). The Rh-atom is oriented above the five-membered ring of the azulene with almost equal Rh—C distances to all five C-atoms of the ring. The (Z,Z)-cycloocta-1,5-diene ring occurs in two enantiomorphic distorted (C2v → C2) tub conformations in the crystals (Fig. 3). In CDCl3 solution, the cod ligand in the complexes 3 shows a dynamic behavior on the 1H-NMR time scale which is best explained by rotation of the cod ligand relative to the azulene ligands around an imaginary cod—Rh—azulene axis. The new complexes 3 catalyze the formation of heptalene-1,2-dicarboxylates 2 from dimethyl acetylenedicarboxylate (ADM) and the corresponding azulenes 1 just as effectively as [RuH2(PPh3)4] and the analogous [RhH(PPh3)4] complex in MeCN solution (Table 3). On grounds of simplicity, 3 can be generated in situ, when [RhCl(cod)]2 is applied as catalyst (Table 3).
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19930760812
