Synthesis and Reactivity of Titanium and Zirconium Complexes Supported by a Multidentate Monoanionic [N2P2] Ligand

The coordination chemistry of titanium and zirconium complexes supported by the monoanionic multidentate ligand [N2P2] (where [N2P2] = tBuN−SiMe2N(CH2CH2PiPr2)2) is presented. The zirconium(IV) halide complex [N2P2]ZrCl3 (1) serves as a precursor to the alkyl species [N2P2]Zr(CH2SiMe3)3 (2) and [N2P2]ZrMe3 (3). The coordination behavior of the [N2P2] ligand in compound 3 is determined using NMR and X-ray diffraction data, and protonation of 3 results in the formation of the cationic species {[N2P2]ZrMe2}{B(C6H5)4} (4). The reduction of 1 in the presence of various traps leads to the isolation of ([N2P2]ZrCl)2(μ-η2:η2-N2) (5), ([N2P2]ZrCl)2(μ-Cl)2 (6), and [N2P2]ZrAr* (9). The titanium(III) halide complex [N2P2]TiCl2 (10) also serves as a precursor to alkyl and reduced species [N2P2]TiMe2 (11) and ([N2P2]TiCl)2(μ-N2) (12). Alkylation of 12 results in the formation of ([N2P2]TiCH2SiMe3)2(μ-N2) (13), and the degree of reduction of the N2 moiety in 12 and 13 is examined using X-ray crystallography and Raman spectroscopy. A series of titanium(IV) imido complexes [N2P2]TiCl(NtBu) (14), [N2P2]TiMe(NtBu) (15), and {[N2P2]Ti(NtBu)}{MeB(C6F5)3)} (16) are synthesized, and the coordination behavior of the [N2P2] ligand is presented.