Activation of C–X (X=Cl or Br) bonds in 2-halobenzaldehydes as their 2-pyridylhydrazone derivatives: oxidative addition to tungsten(0) to give aryl–tungsten(II) complexes
作者:Sarath D Perera、Jesus J Fernandez-Sanchez、Bernard L Shaw
DOI:10.1016/s0020-1693(01)00644-2
日期:2001.12
Condensation of 2-pyridylhydrazine, (NC5H4)NHNH2, with the 2-halobenzaldehydes 2,6-dichlorobenzaldehyde, 2-chlorobenzaldehyde or 2-bromobenzaldehyde gave the 2-pyridylhydrazones, (C6H3Cl2-2,6)CH=N-NH(C5H4N) (1a), (C(6)H(4)Cl2)CH=N-NH(C5H4N) (1b) or (C6H4Br-2)CH=N-NH(C5H4N) (1c), respectively. Treatment of 1a with [W(CO)(3)(NCEt)(3)] in warm tetrahydrofuran caused oxidative addition of the C-Cl bond to give the aryl-tungsten(II) complex [W(CO)(3)Cl(C(6)H(3)Cl6)CH=N-NH(C5H4N)-C,N,N}] (2a). Similarly, the hydrazones 1b and 1c, when treated with [W(CO)(3)(NCEt)(3)], gave the aryl-tungsten(II) Complexes [W(CO)(3)Cl(C6H4)CH=N-NH(C5H4N)-C,N,N] (2b) and [W(CO)(3)Br(C6H4)CH=N-NH(C5H4N)-C,N,N}] (2c). H-1 and C-13-H-1} NMR, IR and mass spectral data are given. (C) 2001 Elsevier Science B.V. All rights reserved.