Titanium and zirconium (triphenylsilyl)imido complexes are available through transimination from the tert-butylimido complexes with H2NSiPh3. The useful starting material Ti(NSiPh3)Cl2(py)2 (1) is prepared in 88% yield by treatment of Ti(NBu t)Cl2(py)3 with H2NSiPh3. Imido 1 is a dimer in the solid state with bridging chlorides; however, solution molecular weight studies indicate that 1 is a monomer in CH2Cl2. 1 reacts with 4,4'-di-tert-butyl-2,2'-bipyridine (bpy) to generate the pseudo-octahedral Ti(NSiPh3)(bpy)(py)Cl2 (2) in 74% recrystallized yield. Replacement of the chloride ligands of 1 with 2 equiv of Lidap, 1 equiv of Libap, or 1 equiv of Lipap afforded the pyrrolylimido complexes Ti(NSiPh3)(dap)2 (3), Ti(NSiPh3)(bap)Cl (4), and Ti(NSiPh3)(pap)Cl (5), respectively. The reaction of 2 equiv of neophyl (Nph) magnesium bromide with 1 provided [Ti(μ-NSiPh3)(Nph)2]2 (6) in 59% yield. The pseudo-octahedral complex Ti(NSiPh3)(dpma)(bpy) (8) was available through addition of Li2dpma to 1, forming Ti(NSiPh3)(dpma)(py)2 (7) followed by treatment with bpy. Alternatively, 8 was prepared by addition of bpy and H2NSiPh3 to Ti(NMe2)2(dpma). The zirconium tert-butylimido complex Zr(NBu t)(dpma)(bpy) (9) was available in 43% yield by treatment of Zr(NMe2)2(py)(dpma) with bpy and H2NBu t. Transimination on 9 with H2NSiPh3 provided the (triphenylsilyl)imido complex Zr(NSiPh3)(dpma)(bpy) (10) in 34% yield. In an unusual transformation, 10 reacts with excess sodium 2,6-dimethylphenoxide in THF to afford [Na(bpy)][Zr(dpma)(OAr)3] (11), where the Na coordinates to the bpy and both pyrrole rings of the dpma in an η5 fashion. Compounds 1, 5, 6, 8, and 11 were structurally characterized.

Syntheses and properties of group-4 complexes incorporating the tridentate, dianionic ligand N,N-(dipyrrolyl-α-methyl)-N-methylamine, dpma, have been investigated. Addition of 1 equiv of H2dpma to Ti(NMe2)4 and Zr(NMe2)4 results in transamination with 2 dimethylamides providing Ti(NMe2)2(dpma) and Zr(NMe2)2(NHMe2)(dpma), respectively. Addition of 2 equiv of H2dpma to Zr(NMe2)4 and Hf(NMe2)4 results in production of the homoleptic complexes Zr(dpma)2 and Hf(dpma)2. Conversely, treatment of Ti(NMe2)4 with 2 equiv of H2dpma does not provide Ti(dpma)2, which was available by addition of 2 Li2dpma to TiCl4. The properties of the isostructural series M(dpma)2 were investigated by single crystal X-ray diffraction, cyclic voltammetry, 14N NMR, and other techniques. By 14N NMR, it was found that the pyrrolyl resonance chemical shift changes approximately linearly with the electronegativity of the metal center, which was attributed to π-interaction between the pyrrolyl nitrogen lone pair and the metal. Other complexes produced during this study include Ti(CH2SiMe3)(NMe2)(dpma), TiCl2(THF)(dpma), and Ti(OCH2CF3)2-(THF)(dpma). Two isomers for Ti(CH2SiMe3)(NMe2)(dpma) were isolated and characterized.

The multigram syntheses of the protio ligands (2-NC5H4)CH2N(CH2CH2NHSiMe2R)2 (R=Me,H2N2NN'3;R=tBu,H2N2NN* 4) are described via reactions of the previously reported (2-NC5H4)CH2N(CH2CH2NH2)2 (1). A new synthesis of 1 is reported starting from 2-aminomethylpyridine and N-tosylaziridine, proceeding via (2-NC5H4)CH2N(CH2-CH2NHTs)2 (2). Reaction of H2N2NN'or H2N2NN* with nBuLi gives good yields of the dilithiated derivatives Li2N2-NN'and Li2N2NN*. Reaction of H2N2NN' or H2N2NN* with [MCl2(CH2SiMe3)2(Et2O)2] gives the cis-dichloride complexes [MCl2(L)](L=N2NN',M=Zr 7 or Hf 8; L=N2NN*, M=Zr 9). The corresponding reactions of H2N2NN'or H2N2NN* with [Zr(NMe2)4] afford the bis(dimethylamide) derivatives [Zr(NMe2)2(L)] (L=N2NN'10 or N2NN* 11). All of these protonolysis reactions proceed smoothly and in good yields. Attempts to prepare the titanium complexes [Ti(X)2(N2NN')] (X=Cl or NMe2) were unsuccessful. The X-ray crystal structures of (2-NC5H4)CH2N(CH2CH2-NHTs)2

The component solubilities of the HCl-MgCl2-H2O systemat 40◦C were calculated by using Pitzer's ion-interaction model and the solubility equilibrium constant of HCl·MgCl2·7H2O at 40℃ was evaluated according to the solubility data for the HCl-MgCl2-H2O system at −19.8,0,20,25 and 50℃. This study can provide the parameters necessary for solubility prediction for the HCl-LiCl-MgCl2-H2O system at 40◦C and supply a theoretical basis for the manufacturing process which was proposed by Gao and employed to extract MgCl2·6H2O from salt lake brine.