Reaktionen von [(Mes)Os(CO)C1 2] mit alkyl-grignardreagenzien: Ein einfacher weg zu carbonyl(olefin)osmium(0)-komplexen

Abstract

From [(MeS)Os(CO)Cl 2] ( 2) and RMgX, both dialkylosmium(II) complexes [(Mes)OsR2(CO)] ( 7: R = C 2H 5; 10: R = n-C 3H 7; 12: R = i-C 3H 7; 14: R = n-C 4H 9) and alkyl(halogeno)osmium(II) derivatives [(Mes)OsR(CO)X] ( 6: R = C 2H 5, X = I; 9: R = n-C 3H 7, X = I; 11: R =i-C 3H 7, X = I; 15: R = n-C 4H 9, X = I; 16: R = CH 2CH 2Ph, X = Br) have been prepared. It is shown that the type of Grignard reagent has a significant influence on the course of the reaction: whereas from 2 and i-C 3H 7Mgl, besides the diiodo compound [(Mes)Os(CO)I 2] ( 8) only the alkyl(iodo) complex 11 is formed, the corresponding reaction of 2 with i-C 3H 7MgX leads predominantly (X = Br) or exclusively (X = Cl) to the formation of the bis(isopropyl) derivative 12. Stepwise treatment of [(Mes)OsR(CO)X] ( 6, 9, 11, 15, 16) with AgBF 4 and Al 2O 3 gives the carbonyl(olefin)osm ium(0) complexes [(Mes)Os(CO)(CH2CHR)] ( 4: R = H; 13: R = CH 3; 17: R = C 2H 5; 18: R = C 6H 5) in good to excellent yields. For 13, 17 and 18, a mixture of exo/ endo isomers is obtained. Compounds 13 and 17 have also been prepared by hydride abstraction from [(Mes)Os(CH 3)(C 2H 5)(CO)] ( 19) or 7 with [CPh 3]PF 6, followed by deprotonation of the hydrido(olefin)osmium cation [(Mes)OsH(CH 2CHR)(CO)] + with either NaH or basic Al 2O 3.