197023-07-7Relevant academic research and scientific papers
Amido, imido and carbene complexes of chromium
Danopoulos, Andreas A.,Hankin, Danielle M.,Wilkinson, Geoffrey,Cafferkey, Sean M.,Sweet, Tracy K.N.,Hursthouse, Michael B.
, p. 3879 - 3892 (2008/10/09)
Interaction of CrCl2 with LiNHAr*, Ar* = 2,6-Pri2C6H3, in thf gave the homoleptic amide CrII (NHAr*)4 [Li(thf)]2 (1), which resisted further deprotonation by strong bases. Interaction of Cr(Nmes)2 Cl2,mes = 2,4,6-Me3C6H2, with LiNHmes gave the mesitylimido complex [CrVI(Nmes)3(NHmes)]Li(Et2O)2 (2), which also resisted further deprotonation. Pentamethylcyclopentadienyl chromium(V) complexes Cp*Cr(NAr′)X2, X = SC6H5, Ar′ = 2-PriC6H4, (3) ; 4-Me-C6H4 (4) ; 2-Bu′C6H4, (5), have been prepared by interaction of (Cp*CrBr2)2 with Li(Ar′NSPh). Reaction of (Cp*CrBr2)2 with mesitylnitrene, generated from mesN3 in situ, gave the ionic CrIII species [Cp*CrBr3][mesNH3], (6). (3) and (5) as well as the previously reported Cp*Cr(NBut)X2 can be transformed to the corresponding chlorides (7)-(9), by reaction with BCl3. Finally, interactions of Cr(mes)2(thf)3 with the carbene CN(Pri)C2Me2NPri = L gave Cr(mes)2L2 (10). The X-ray crystal structures of compounds (1)-(3), (6), (7), (9) and (10) have been determined. (1) is a molecular cluster with square planar CrII and with two [Li(thf)]+ ions bridging the nitrogen atoms of pairs of amide ligands on opposite sides of the square. (2) has a distorted tetrahedral metal geometry with one [Li(Et2O)2]+ ion bridging the nitrogen atoms of two imido ligands. (3) has a monomeric pseudo tetrahedral structure, as do (7) and (9) and the anion in (6). (10) has a trans square planar structure in which the Cr - C distances to the mesityl and carbene ligands are equal within error.
