Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, UK.
Chemistry. 2013 Mar 25;19(13):4198-216. doi: 10.1002/chem.201203905. Epub 2013 Feb 11.
We report a detailed study of the reactions of the Ti=NNCPh2 alkylidene hydrazide functional group in [CpTi{MeC(NiPr)2}(NNCPh2)] (8) with a variety of unsaturated and saturated substrates. Compound 8 was prepared from [CpTi{MeC(NiPr)2}(NtBu)] and Ph2CNNH2. DFT calculations were used to determine the nature of the bonding for the Ti=NNCPh2 moiety in 8 and in the previously reported [Cp2Ti(NNCPh2)(PMe3)]. Reaction of 8 with CO2 gave dimeric [(CpTi{MeC(NiPr)2}{μ-OC(NNCPh2)O})2] and the "double-insertion" dicarboxylate species [CpTi-{MeC(NiPr)2}{OC(O)N(NCPh2)C(O)O}] through an initial [2+2] cycloaddition product [CpTi{MeC(NiPr)2}{N(NCPh2)C(O)O}], the congener of which could be isolated in the corresponding reaction with CS2. The reaction with isocyanates or isothiocyanates tBuNCO or ArNCE (Ar = Tol or 2,6-C6 H3 iPr2 ; E = O, S) gave either complete NNCPh2 transfer, [2+2] cycloaddition to Ti=Nα or single- or double-substrate insertion into the Ti=Nα bond. The treatment of 8 with isonitriles RNC (R = tBu or Xyl) formed σ-adducts [CpTi{MeC(NiPr)2}(NNCPh2)(CNR)]. With Ar(F5)CCH (Ar(F5)=C6F5) the [2+2] cycloaddition product [CpTi{MeC(NiPr)2}{N(NCPh2)C(Ar(F5))C(H)}] was formed, whereas with benzonitriles ArCN (Ar = Ph or Ar(F5)) two equivalents of substrate were coupled in a head-to-tail manner across the Ti=Nα bond to form [CpTi{MeC(NiPr)2}{N(NCPh2)C(Ar)NC(Ar)N}]. Treatment of 8 with RSiH3 (R = aryl or Bu) or Ph2SiH2 gave [CpTi{MeC(NiPr)2}{N(SiHRR')N(CHPh2)}] (R' = H or Ph) through net 1,3-addition of Si-H to the N-N=CPh2 linkage of 8, whereas reaction with PhSiH2X (X = Cl, Br) led to the Ti=Nα 1,2-addition products [CpTi{MeC(NiPr)2}(X){N(NCPh2)SiH2Ph}].
我们报告了 [CpTi{MeC(NiPr)2}(NNCPh2)]（8）中 Ti=NNCPh2 亚烷基腙官能团与各种不饱和和饱和底物反应的详细研究。化合物 8 是由 [CpTi{MeC(NiPr)2}(NtBu)] 和 Ph2CNNH2 制备的。DFT 计算用于确定 8 中 Ti=NNCPh2 部分和之前报道的 [Cp2Ti(NNCPh2)(PMe3)] 中的键合性质。8 与 CO2 的反应生成二聚体[(CpTi{MeC(NiPr)2}{μ-OC(NNCPh2)O})2]和“双插入”二羧酸酯物种[CpTi-{MeC(NiPr)2}{OC(O)N(NCPh2)C(O)O}]，通过初始[2+2]环加成产物[CpTi{MeC(NiPr)2}{N(NCPh2)C(O)O}]，其同类物可以在与 CS2 的相应反应中分离出来。与异氰酸酯或异硫氰酸酯 tBuNCO 或 ArNCE（Ar = Tol 或 2,6-C6 H3 iPr2；E = O，S）的反应要么完全转移 NNCPh2，要么 Ti=Nα 发生[2+2]环加成，要么 Ti=Nα 键单或双插入底物。8 与异腈 RNC（R = tBu 或 Xyl）的处理形成σ-加合物[CpTi{MeC(NiPr)2}(NNCPh2)(CNR)]。与 Ar(F5)CCH（Ar(F5)=C6F5）形成[2+2]环加成产物[CpTi{MeC(NiPr)2}{N(NCPh2)C(Ar(F5))C(H)}]，而与苯甲腈 ArCN（Ar = Ph 或 Ar(F5)）则通过 Ti=Nα 键的头到尾方式偶联两个当量的底物，形成[CpTi{MeC(NiPr)2}{N(NCPh2)C(Ar)NC(Ar)N}]。8 与 RSiH3（R = 芳基或 Bu）或 Ph2SiH2 的处理通过 Si-H 对 8 的 N-N=CPh2 键的净 1,3-加成形成[CpTi{MeC(NiPr)2}{N(SiHRR')N(CHPh2)}]（R'=H 或 Ph），而与 PhSiH2X（X = Cl，Br）反应则导致 Ti=Nα 1,2-加成产物[CpTi{MeC(NiPr)2}(X){N(NCPh2)SiH2Ph}]。
