Solvent Impact on the Diversity of Products in the Reaction of Lithium Diphenylphosphide and a Ti(III) Complex Supported by a tBu2P-P(SiMe3) Ligand.

We present two important trends in the reactivity of the titanium complex [MeNacNacTi(Cl){η2-P(SiMe3)-PtBu2}] (MeNacNac- = [Ar]NC(Me)CHC(Me)N[Ar]; Ar = 2,6-iPr2Ph) with nucleophilic reagents RLi (R = Ph2P, tBuO, (Me3Si)2N, and tBu2N) depending on the reaction medium. Reaction in nonpolar solvent (toluene) leads to three main products: via an autoredox process and nucleophilic substitution at the Ti-atom to afford the Ti(IV) complex [MeNacNacTi(R){η2-P-PtBu2}] (1 for R = PPh2), via the elimination of Me3SiR to afford Ti(III) complex [MeNacNacTi(Cl){η2-P-PtBu2}]-[Li(12-crown-4)2]+ (2), and via 2e- reduction process to afford new ionic complex [{ArNC(Me)CHC(Me)}Ti═NAr{η1-P(SiMe3)-PtBu2}]-[Li(12-crown-4)2]+ (3). Quite differently, the complex [MeNacNacTi(Cl){η2-P(SiMe3)-PtBu2}] reacts with Ph2PLi in THF, unexpectedly yielding two new, four-coordinate Ti(IV) imido complexes 4a [{ArNC(Me)═CHC(H)(Me)-P(PtBu2)}Ti═NAr(Cl)]-[Li(12-crown-4)2]+·(toluene)2 and 4b [{ArNC(CH2)CH═C(Me)-P(PtBu2)}Ti═NAr(Cl)]-[Li(12-crown-4)2]+·(Et2O). Complex 2 dissolved in THF converts to 4a and 4b. 1, 2, 3, 4a, and 4b were characterized by X-ray diffraction. 1, 4a, and 4b were also fully characterized by multinuclear NMR spectroscopy.

The new diphosphanylphosphido complexes of tungsten(vi) and molybdenum(vi). Their synthesis, structures and properties.

We report on the reactivity of R2P-P(Li)-PR'2 (R = tBu, iPr, R' = NEt2, iPr) towards diimido complexes [(dippN)2MCl2·dme] (M = Mo, W and dipp = 2,6-iPr2C6H3). A series of new complexes with diphosphanylphosphido ligands R2P-P-PR'2 were isolated. The solid-state structures of [(dippN)2M(Cl)(1,2-η-iPr2P-P-PiPr2)] (2Mo and 2W) and [(dippN)2M(Cl){1,2-η-tBu2P-P-P(NEt2)2}] (3Mo and 3W) were established by single-crystal X-ray diffraction analysis and indicate a side-on geometry of the R2P-P-PR'2 moiety. 3W and 3Mo are the first triphosphorus complexes with the amido ligand NEt2 on the P atom. [(dippN)2M(Cl)(1,2-η-tBu2P-P-PtBu2)] (1Mo and 1W) and 3Mo and 3W display similar side-on geometry in solution and in the solid state. By contrast, 2Mo and 2W reveal a dynamic behavior in solution. For the first time, the reactivity of diphosphanylphosphido complexes towards different nucleophiles was studied. The complexes react with the phosphorus nucleophile Ph2PLi, yielding phosphanylphosphinidene complexes [(dippN)2M(Cl)(η2-P-PR2)]- Li+ (M = Mo, W) together with related diphosphanes R'2P-PPh2. Carbon nucleophile MeLi does not yield [(dippN)2M(Cl)(η2-P-PR2)]- Li+ but substitutes a Cl ligand at the metal center. Moreover, we compare the coordination of the R2P-P-PR'2 moiety to different metal centers based on DFT methods.

Reactions of Lithiated Diphosphanes R2P-P(SiMe3)Li (R = tBu and iPr) with [MeNacnacTiCl2·THF] and [MeNacnacTiCl3]. Formation and Structure of TitaniumIII and TitaniumIV ß-Diketiminato Complexes Bearing the Side-on Phosphanylphosphido and Phosphanylphosphinidene Functionalities.

ß-Diketiminate complexes of TiIII-containing phosphanylphosphido ligands [MeNacnacTi(Cl){η2-P(SiMe3)-PR2}] (MeNacnac- = [Ar]NC(Me)CHC(Me)N[Ar]; Ar = 2,6-iPr2C6H3) were prepared by reactions of [MeNacnacTiCl2·THF] with lithium derivatives of diphosphanes R2P-P(SiMe3)Li (R = tBu, iPr) in toluene solutions. Surprisingly, reactions of [MeNacnacTiCl2·THF] with R2P-P(SiMe3)Li in THF solutions led to TiIV complexes containing phosphanylphosphinidene ligands [MeNacnacTi(Cl)(η2-P-PtBu2)] via an autoredox path involving a migration of a nitrene NAr from the Nacnac skeleton to the Ti centers. Solid-state structures of [MeNacnacTi(Cl){η2-P(SiMe3)-PtBu2}] (1a) and [MeNacnacTi(Cl)(η2-P-PtBu2)] (two isomers 2a1, 2a2) together with [MeNacnacTi(Cl){η2-P(SiMe3)-PiPr2}] (1b) and [MeNacnacTi(Cl)(η2-P-PiPr2)] (2b) were established by the single-crystal X-ray diffraction and display clearly side-on geometry of the (Me3Si)P-PR2 and P-PR2 moieties in the solid state. Phosphanylphosphinidene complexes [MeNacnacTi(Cl)(η2-P-PR2)] indicate that the 31P NMR resonances of phosphinidene P atoms appear at a very low field in solution and in the solid state.