Electronic Factors Determining the Rearrangement of Dialkylaluminum O,O‘-Chelate Compounds from Dimeric Five- to Monomeric Four-Coordinated Complexes on Dissolution. Structure Investigations of Dialkylaluminum Chelate Derivatives of α- and β-Hydroxy Carbonyl Compounds

Janusz Lewiński , Janusz Zachara , Iwona Justyniak

Abstract

The synthesis and the structure characterization of dialkylaluminum O,O?-chelate complexes derived from α- and ?-hydroxy carbonyl compounds:? α-tropolone (tropH), ethyl rac-lactate (elacH), and 2-acetyl-4-chlorophenol (Cl-acphH), with saturated and conjugated unsaturated bond systems, are reported. The reaction of R3Al with an equimolar amount of the hydroxy carbonyl compound leads to the formation of [R2Al(O,O?)]n chelate complexes [where O,O? = Cl-acph, R = Me (1a); trop, R = Et (2b); elac, R = Me (3)]. According to the X-ray study these compounds are dimeric in the solid state. The aluminum atoms adopt a distorted trigonal bipyramidal geometry with a long internal (in 1a and 2b) or external (in 3) Al?O axial bond. In addition, complex 3 posseses a C2 symmetry, which indicates that the five-coordinated [R2Al(O,O?)]2-type adduct is formed in a highly stereoselective manner. In solution 1a and 2b adducts rearrange to the monomeric four-coordinated chelate complexes, while 3 remains a dimeric structure found in the solid state, as confirmed by cryoscopic molecular weight determination and 1H and 27Al NMR and IR spectroscopy. The influence of the nature of the O,O?-bifunctional ligand on the structure of dialkylaluminum chelate complexes in the solid state and in solution and the geometry of the aluminum coordination sphere are discussed on the basis of the results reported and structural data of related compounds.
Author Janusz Lewiński (FC / DCOC)
Janusz Lewiński,,
- Department Of Catalysis And Organometallic Chemistry
, Janusz Zachara (FC / CICSST)
Janusz Zachara,,
- Chair Of Inorganic Chemistry And Solid State Technology
, Iwona Justyniak
Iwona Justyniak,,
-
Journal seriesOrganometallics, ISSN 0276-7333
Issue year1997
Vol16
No21
Pages4597-4605
ASJC Classification1604 Inorganic Chemistry; 1605 Organic Chemistry; 1606 Physical and Theoretical Chemistry
DOIDOI:10.1021/om961054d
URL http://dx.doi.org/10.1021/om961054d
Languageen angielski
File
organometall1997.pdf 221.31 KB
Score (nominal)40
Publication indicators WoS Citations = 44; Scopus SNIP (Source Normalised Impact per Paper): 1999 = 1.226; WoS Impact Factor: 2006 = 3.632 (2) - 2007=3.46 (5)
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