Oxorhenium(V) complexes with ketiminato ligands: coordination chemistry and epoxidation of cyclooctene.
Rhenium(V) oxo complexes of the type [ReOX(L)(2)] (1-7; X = Cl, Br) containing beta-ketiminate ligands (L = CH(3)C(O)CH(2)C(NAr)CH(3): Ar = Ph (APOH), 2-MePh (MPOH), 2,6-Me(2)Ph (DPOH), 2,6-(i)Pr(2)Ph (DiPOH)) have been prepared by reaction of [ReOX(3)(OPPh(3))(SMe(2))] (X = Cl, Br) with the lithium salts of the corresponding ligands. All compounds have been spectroscopically characterized, showing [ReOX(DiPO)(2)] (X = Cl (1), Br (5)), [ReOX(DPO)(2)] (X = Cl (2), Br (6)), and [ReOX(APO)(2)] (X = Cl (4), Br (7)) to be isomerically pure, in contrast to complex [ReOCl(MPO)(2)] (3), which exhibits a mixture of isomers. Compounds 2, 3, 5, and 7 were crystallographically characterized, showing similar octahedral coordination spheres with trans O horizontal lineRe-O and cis O horizontal lineRe-Cl bonds. However, the coordination of the nitrogen atoms vs each other is found to be cis or trans. Compounds 2 and 5 showed a trans-N,N configuration, for compound 3 both isomers (trans-N,N 3 and cis-N,N 3) were structurally characterized, and 7 gave a cis-N,N configuration. Compounds 1-6 are catalyst precursors for the epoxidation of cis-cyclooctene with 3 equiv of tert-butyl hydroperoxide (TBHP). Yields of the formed epoxide were up to 55% with all precursors, except with 2 and 6, where only up to 13% of epoxide was obtained under analogous conditions.
Schröckeneder
Albert
A
Institute of Chemistry, Karl-Franzens-University Graz, Schubertstrasse 1, 8010 Graz, Austria.
Traar
Pedro
P
Raber
Georg
G
Baumgartner
Judith
J
Belaj
Ferdinand
F
Mösch-Zanetti
Nadia C
NC
D002384:Catalysis; D034242:Cyclooctanes / Q000138:chemical synthesis* / Q000737:chemistry; D004852:Epoxy Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D007097:Imines / Q000737:chemistry*; D008024:Ligands; D015394:Molecular Structure; D009570:Nitriles / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D012211:Rhenium / Q000737:chemistry*; D013237:Stereoisomerism
D034242:Cyclooctanes; D004852:Epoxy Compounds; D007097:Imines; D008024:Ligands; D009570:Nitriles; D009942:Organometallic Compounds; C542835:ketimine; C015428:perrhenate; D012211:Rhenium