The Chemistry of Vanadium-Carbon Bond Functionalities over an Oxo-Surface Defined by the Calix[4]arene Skeleton: The Redox Relationship between Vanadium(III) and Vanadium(IV) Assisted by Carbon-Oxygen
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- 作者：Barbara Castellano ; Euro Solari ; Carlo Floriani ; Nazzareno Re ; Angiola Chiesi-Villa ; and Corrado Rizzoli
- 刊名：Organometallics
- 出版年：1998
- 出版时间：May 25, 1998
- 年：1998
- 卷：17
- 期：11
- 页码：2328 - 2336
- 全文大小：171K
- 年卷期：v.17,no.11(May 25, 1998)
- ISSN：1520-6041
文摘
This report deals with the chemistry of V-C functionalitiesanchored to a quasi-planarO4 matrix represented here by the[p-But-calix[4]-(OMe)2(O)2]2-macrocycle. The startingmaterial[p-But-calix[4]-(OMe)2(O)2V-Cl],2, has been converted into the correspondingalkyland aryl derivatives[p-But-calix[4]-(OMe)2(O)2V-R](R = Me, 3; R = CH2Ph, 4; R=p-MeC6H4, 5) byconventional procedures. The structure of 5 reveals theself-assembling ofthe monomeric unit into a columnar arrangement with thep-tolyl substituent functioningas a guest moiety in a neighboring unit. Complexes3-5 undergo migratory insertionreactions with CO and ButNC to the corresponding
2-acyls[p-But-calix[4]-(OMe)2(O)2V(2-COR)] (R = Me, 6; R = CH2Ph,7) and 2-iminoacyls[p-But-calix[4]-(OMe)2(O)2V{2-C(NBut)R}] (R = Me, 8; R =CH2Ph, 9; R =p-MeC6H4, 10), thereaction with CO beingstrongly dependent on the R substituent. The structural model forthe hexacoordinateintermediate leading to the inserted product is exemplified by thed2 high-spin[p-But-calix[4]-(OMe)2(O)2V(Cl)(CNBut],11, and proves the presence of four available orbitals atthemetal for driving the reactivity in the[p-But-calix[4]-(OMe)2(O)2V]fragment. The bondingmode of the organic functionalities at the metal and the conversion ofthe alkyl substituentinto the 2-acyl have been inspected by extendedHückel calculations. The oxidativedemethylation of 3 and 5 by a controlled amountof iodine opened an interesting syntheticroute to the corresponding vanadium(IV) organometallic derivatives[p-But-calix[4]-(OMe)(O)3V-X] (X = Cl, 12; X =p-MeC6H4, 13). Astructural report on 2, 5, and 9 isincluded.
2-acyls[p-But-calix[4]-(OMe)2(O)2V(2-COR)] (R = Me, 6; R = CH2Ph,7) and 2-iminoacyls[p-But-calix[4]-(OMe)2(O)2V{2-C(NBut)R}] (R = Me, 8; R =CH2Ph, 9; R =p-MeC6H4, 10), thereaction with CO beingstrongly dependent on the R substituent. The structural model forthe hexacoordinateintermediate leading to the inserted product is exemplified by thed2 high-spin[p-But-calix[4]-(OMe)2(O)2V(Cl)(CNBut],11, and proves the presence of four available orbitals atthemetal for driving the reactivity in the[p-But-calix[4]-(OMe)2(O)2V]fragment. The bondingmode of the organic functionalities at the metal and the conversion ofthe alkyl substituentinto the 2-acyl have been inspected by extendedHückel calculations. The oxidativedemethylation of 3 and 5 by a controlled amountof iodine opened an interesting syntheticroute to the corresponding vanadium(IV) organometallic derivatives[p-But-calix[4]-(OMe)(O)3V-X] (X = Cl, 12; X =p-MeC6H4, 13). Astructural report on 2, 5, and 9 isincluded.