Titanium Imido Complexes Supported by Amidinate Ligands: Synthesis, Solution Dynamics, and Solid State Structures

Reaction of Li[PhC(NSiMe3)2] with the complexes [Ti(NR)Cl2(py)3] affords the corresponding (N,N‘-bis(trimethylsilyl)benzamidinato)titanium imido derivatives [Ti(NR){PhC(NSiMe3)2}Cl(py)2] [R = But (1), 2,6-C6H3Me2 (2), 2,6-C6H3Pri2 (3)], which, in solution, exist in temperature-dependent, dynamic equilibrium with their mono(pyridine) homologues [Ti(NR){PhC(NSiMe3)2}Cl(py)] and free pyridine. Kinetic and thermodynamic data for these processes are reported, and the relative contributions of the ΔH and ΔS terms associated with all three equilibria are identified. The arylimido complexes 2 and 3 may also be prepared by treating 1 with the appropriate arylamine. Reaction of Li[MeC(NC6H11)2] with [Ti(NBut)Cl2(py)3] gives the binuclear N,N‘-bis(cyclohexyl)acetamidinato derivative [Ti2(μ-NBut)2{MeC(NC6H11)2}2Cl2] (4). The X-ray structures of 2 and 4 have been determined. Crystal data for 2:  triclinic, P1̄, a = 11.219(5) Å, b = 12.131(6) Å, c = 13.208(7) Å, α = 80.34(5)°, β = 87.41(4)°, γ = 75.13(3)°, V = 1722.1(15) Å3, Z = 2, R = 0.054, Rw = 0.056. Crystal data for 4:  triclinic, P1̄, a = 10.455(3) Å, b = 10.637(5) Å, c = 11.024(3) Å, α = 90.52(4)°, β = 112.62(3)°, γ = 114.10(3)°, V = 1012.8(10) Å3, Z = 1, R = 0.0453, Rw = 0.0495

Mononuclear Niobium Imido and Oxo Complexes Supported by <i>N,N</i>‘-Bis(trimethylsilyl)benzamidinate Ligands. X-ray Structures of [Nb(NBu^t){PhC(NSiMe₃)₂}Cl₂(py)] and [Nb(O){(4-C₆H₄Me)C(NSiMe₃)₂}₂Cl]

Mononuclear Niobium Imido and Oxo Complexes Supported by N,N‘-Bis(trimethylsilyl)benzamidinate Ligands. X-ray Structures of [Nb(NBut){PhC(NSiMe3)2}Cl2(py)] and [Nb(O){(4-C6H4Me)C(NSiMe3)2}2Cl

New Titanium Complexes Containing an Amidinate−Imide Supporting Ligand Set: Cyclopentadienyl, Alkyl, Borohydride, Aryloxide, and Amide Derivatives

A range of chloride metathesis reactions of the monomeric titanium N,N‘-bis(trimethylsilyl)benzamidinato−imido complexes [Ti(NBut){(4-C6H4R)C(NSiMe3)2}Cl(py)2] (R = H (1) or OMe (2)) are described. Thus, reaction of 1 or 2 with LiC5H5 gave the half-sandwich compounds [Ti(NBut){(4-C6H4R)C(NSiMe3)2}(η-C5H5)] (R = H (3) or OMe (4)). Reaction of 1 with LiCH2SiMe3 or LiCH(SiMe3)2 gave the 14-electron, first fully characterized group 4 imido−alkyl derivatives [Ti(NBut){PhC(NSiMe3)2}{CH(R)SiMe3}(py)] (R = H (5) or SiMe3 (6)). For comparative purposes, the 16-electron half-sandwich imido−alkyl complex [Ti(NBut)(ηC5Me5)(CH2SiMe3)(py)] (7) was prepared from LiCH2SiMe3 and [Ti(NBut)(η-C5Me5)Cl(py)]. Reaction of 1 with LiBH4 gave the η3-borohydride derivative [Ti(NBut){PhC(NSiMe3)2}(η3-BH4)(py)] (8), while treatment of 1 with LiN(SiMe3)2, LiO-2,6-C6H3R2 (R = Me or But), or LiPhC(NSiMe3)2 gave the corresponding aryloxide, amide, or bis(benzamidinate) titanium imido complexes [Ti(NBut){PhC(NSiMe3)2}{N(SiMe3)2}(py)] (9), [Ti(NBut){PhC(NSiMe3)2}(O-2,6-C6H3R2)(py)] (R = Me (10) or But (11)), or [Ti(NBut){PhC(NSiMe3)2}2(py)] (13). Activation parameters for the concerted, restricted rotation of the aryloxide and benzamidinate ligands in 11 are reported and point to a dissociatively activated mechanism. The X-ray structures of 5 and 7 have been determined