| Sumari: | New group 4 compounds supported by the tetradentate diamide-diamine ligand N2NN′ are reported (N2NN′ = (2-C 5H4N)CH2N(CH2CH 2NSiMe3)2) along with some comparative studies with the new bis(alkoxide)-diamine ligand O2NN′ (O 2NN′ = (2-C5H4N)CH2N(CH 2-CMe2O)2). Reaction of the previously described ZrCl2(N2NN′) (1) with 2 equiv of MeLi or PhCH2MgCl gave ZrR2(N2NN′) (R = Me (2) or CH2Ph (3)). Reaction of 1 with 1 equiv of RCH2MgCl gave the monoalkyl analogues ZrCl(R)(N2NN′) (R = CH2Ph (6) or CH2SiMe3 (7)). Reaction of Zr(CH2R) 4 (R = SiMe3 or CMe3) with H2N 2NN′ in C6D6 gave the corresponding Zr(CH2R)2(N2NN′), but these decomposed over several hours. Reaction of 1 with allylmagnesium chloride gave ZrCl{(2-NC5(6-C3H5)H4)CH 2N(CH2CH2NSiMe3)2}, in which the pyridyl group has undergone nucleophilic attack. Reaction of 2 with BArF3 (ArF = C6F5) in benzene led to the cyclometalated cation [Zr{(2-NC5H 4)CH2N(CH2CH2NSiMe 3)(CH2CH2NSiMe2CH 2-)}]+ via SiMe3 group C-H activation, but in the presence of THF the methyl cation [ZrMe-(THF)(N2NN′)] + was formed. Reaction of 6 with BAr3F gave the chloride cation [ZrCl(N2-NN′)]+. Reaction of Li2N2NN′ with Ti(NR)Cl2(py)3 gave the five-coordinate imides Ti(NR)(N2NN′) (R = tBu or Ar (15), Ar = 2,6-C6H3iPr2). Zirconium imides Zr(NAr)(N2NN′) and Zr(NtBu)-(py)(N2NN′) (18) were prepared by sequential reaction of 1 with LiCH2SiMe3 (2 equiv) and the appropriate amine and pyridine for the latter. Reaction of 1 with LiNH tBu (2 equiv) gave Zr(NHtBu)2(N 2NN′). Reaction of 18 with piperidine gave Zr(NH tBu)(NC5H10)(N2NN′) (19) via N-H bond activation. For comparative purposes the group 5 imides M(N tBu)Cl(N2NN′) (M = Nb (20) or Ta (21)) were prepared from Li2N2NN′ and the corresponding M(N t-Bu)Cl3(py)2. Reaction of 2- aminomethylpyridine with an excess of isobutylene oxide afforded H 2O2NN′ (22). Reaction of H2O 2NN′ (1 or 2 equiv) with Ti(NMe2)4 gave Ti(O2NN′)2, which reacted with TiCl 4(THF)2 to form TiCl2(O2NN′). Reaction of H2O2NN′ with Zr(CH2SiMe 3)2-Cl2(Et2O)2, Zr(NMe2)4, or Zr(CH2SiMe3) 4 gave ZrX2(O2NN′) (X = Cl, NMe 2, or CH2SiMe3 (27)). Reaction of 27 with BAr3F in the presence of THF formed [Zr(CH 2SiMe3)(THF)(O2NN′)]+, but in the absence of a Lewis base the μ-alkoxide-bridged dimer [Zr 2(CH2SiMe3)2(O2NN′) 2]2+ was formed. The compounds 3, 6, 15, 19, 21, 22, and 27 were crystallographically characterized. © 2005 American Chemical Society.
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