Institut für Anorganische und Analytische Chemie, Technische Universität Carolo-Wilhelmina, Hagenring 30, 38106 Braunschweig, Germany.
Inorg Chem. 2012 Apr 2;51(7):4368-78. doi: 10.1021/ic300129z. Epub 2012 Mar 15.
The reaction of the cycloheptatrienylzirconium half-sandwich complex [(η(7)-C(7)H(7))ZrCl(tmeda)] (1) (tmeda = N,N,N',N'-tetramethylethylenediamine) with Li(Im(Dipp)N), generated from bis(2,6-diisopropylphenyl)imidazolin-2-imine (Im(Dipp)NH) with methyllithium, yields the imidazolin-2-iminato complex [(η(7)-C(7)H(7))Zr(Im(Dipp)N)(tmeda)] (2). The corresponding tmeda-free complex [(η(7)-C(7)H(7))Zr(Im(Dipp)N)] (5) can be synthesized via the 1,3-bis(trimethylsilyl)allyl complex [(η(7)-C(7)H(7))Zr{η(3)-C(3)H(3)(TMS)(2)}(THF)] (3; TMS = SiMe(3)), which undergoes an acid-base reaction with Im(Dipp)NH to form 5 and 1,3-bis(trimethylsilyl)propene. 5 exhibits an unusual one-legged piano stool ("pogo stick") geometry with a particularly short Zr-N bond of 1.997(2) Å. Addition of 2,6-dimethylphenyl or tert-butyl isocyanide affords the complexes [(η(7)-C(7)H(7))Zr(Im(Dipp)N)(CNR)] (R = o-Xy, 6; R = t-Bu, 7), while the reaction with 2,6-dimethylphenyl isocyanate results in a [2 + 2] cycloaddition to form the ureato(1-) complex [(η(7)-C(7)H(7))Zr{Im(Dipp)N(C═O)N-o-Xy}] (8). 5 can also act as an initiator for the ring-opening polymerization of ε-caprolactone. These reactivity patterns together with density functional theory calculations reveal a marked similarity of the bonding in imidazolin-2-iminato and conventional imido transition-metal complexes.
环庚三烯基锆半夹心配合物[(η(7)-C(7)H(7))ZrCl(tmeda)]（1）（tmeda=N,N,N',N'-四甲基乙二胺）与双(2,6-二异丙基苯基)咪唑啉-2-亚胺（Im(Dipp)NH）与甲基锂生成的 Li(Im(Dipp)N)反应，生成咪唑啉-2-亚胺配合物[(η(7)-C(7)H(7))Zr(Im(Dipp)N)(tmeda)]（2）。相应的无 tmeda 配合物[(η(7)-C(7)H(7))Zr(Im(Dipp)N)]（5）可以通过 1,3-双（三甲基甲硅烷基）烯丙基配合物[(η(7)-C(7)H(7))Zr{η(3)-C(3)H(3)(TMS)(2)}(THF)]（3；TMS=SiMe(3)）合成，该配合物与 Im(Dipp)NH 发生酸碱反应生成 5 和 1,3-双（三甲基甲硅烷基）丙烯。5 呈现出异常的单腿钢琴凳（“跳跳杆”）几何形状，Zr-N 键特别短，为 1.997(2)Å。添加 2,6-二甲基苯基或叔丁基异氰酸酯得到配合物[(η(7)-C(7)H(7))Zr(Im(Dipp)N)(CNR)]（R=o-Xy，6；R=t-Bu，7），而与 2,6-二甲基苯基异氰酸酯的反应导致[2 + 2]环加成，形成脲（1-）配合物[(η(7)-C(7)H(7))Zr{Im(Dipp)N(C═O)N-o-Xy}]（8）。5 还可以作为ε-己内酯开环聚合的引发剂。这些反应模式以及密度泛函理论计算揭示了咪唑啉-2-亚胺和传统亚胺过渡金属配合物的键合具有明显的相似性。
