An EPR Study of the Vanadium Species Formed upon Interaction of Vanadyl N and C-Capped tris(phenolate) Complexes with AlEt3 and AlEt2Cl
Full article
| Общее |
Language:
Английский,
Genre:
Full article,
Status:
Published,
Source type:
Original
|
| Journal |
Journal of Molecular Catalysis A: Chemical
ISSN: 1381-1169
|
| Output data |
Year: 2009,
Volume: 303,
Number: 1-2,
Pages: 23-29
Pages count
: 7
DOI:
10.1016/j.molcata.2008.12.013
|
| Tags |
Copolymer, Cyclic carbonate, Ionic liquid |
| Authors |
Soshnikov Igor E.
1,2
,
Semikolenova Nina V.
1
,
Bryliakov Konstantin P.
1,2
,
Zakharov Vladimir A.
1
,
Redshaw Carl
3
,
Talzi Evgenii P.
1,2
|
| Affiliations |
| 1 |
Boreskov Institute of Catalysis SB RAS
|
| 2 |
Novosibirsk State University
|
| 3 |
University of East Anglia
|
|
Funding (2)
|
1
|
Russian Foundation for Basic Research
|
06-03-32700
|
|
2
|
Royal Society
|
2006/R4-IJP
|
Reactions of vanadyl N and C-capped tris(phenolate) complexes 1 and 2 (Scheme 1) with AlEt3 and AlEt2Cl, in the absence and in the presence of ethyltrichloroacetate (ETA), were monitored by EPR. It was shown, that vanadium(IV) complexes with proposed structures LNVIV(Et)(AlEt3) and LNVIV(Et)(AlEt2Cl) are formed at the initial stage of interaction of 1 with AlEt3 and AlEt2Cl, respectively (LN are unidentified products of interaction of the initial N-capped ligand and Vdouble bond; length as m-dashO moiety with aluminum alkyls). In the absence of re-activator (ETA), LNVIV(Et)(AlEt3) and LNVIV(Et)(AlEt2Cl) rapidly convert at room temperature to V(III) species, which relatively slowly transform to complexes LNVIIEt2 and LNVII(Et)Cl. Concentration of LNVIV(Et)(AlEt2Cl) dramatically increases in the presence of ETA, that correlates with the increase of the polymerization activity of the catalyst system 1/AlEt2Cl. The complex LNVIV(Et)(AlEt2Cl) can be precursor of the active species of polymerization. Similarly, ETA increases concentration of vanadium(IV) complex LCVIV(Et)(AlEt2Cl) in the catalyst system 2/AlEt2Cl (LC are unidentified products of interaction of the initial C-capped ligand and Vdouble bond; length as m-dashO moiety with aluminum alkyls). The complex LCVIV(Et)(AlEt2Cl) can be precursor of the active species of polymerization.