From Neutral to Ionic Species: Syntheses and X‐ray Crystallographic and Multinuclear NMR Spectroscopic Studies of Li···P(SiMe 3 )–P t Bu 2 and Its Solvent Complexes

Two complementary approaches for the synthesis and isolation of stable phosphanylphosphaalkenes

A new series of compounds formed in a one-step  reaction (Phospha–Wittig  or phospha–Peterson), containing the CP–P moiety was synthesized and characterized. These species are stable under atmospheric conditions and are resistant to hydrolysis.

Synthesis of compounds with C-P-P and C[double bond, length as m-dash]P-P bond systems based on the phospha-Wittig reaction

A reactivity study of a β-diketiminate titanium(iii) phosphanylphosphido complex [^MeNacNacTi(Cl){η²-P(SiMe₃)-PtBu₂}] (1) towards ketones such as benzophenone, 9-fluorenone, acetophenone, cyclopentanone, cyclohexanone and cycloheptanone is reported. The reactions of 1 with aromatic ketones (without α-protons) directly lead to the Ti(iii) complex [^MeNacNacTi(μ²-Cl)(OSiMe₃)] (5) and Ti(iv) complexes with the pinacol condensation product [^MeNacNacTi(OSiMe₃)(η²-pinacolate)] (3), and phosphanylphosphaalkenes Ph₂C[double bond, length as m-dash]P-PtBu₂ (2) and (fluorenyl)C[double bond, length as m-dash]P-PtBu₂ (6), respectively. The reaction with acetophenone leads to the titanium(iii) complex with the aldol condensation product as ligand [^MeNacNacTi(Cl){OC{Me(Ph)}CH₂(C[double bond, length as m-dash]O)Ph}] (8) and in parallel to phosphanylphosphaalkene (Ph)MeC[double bond, length as m-dash]P-PtBu₂ (9) and 5. The reactions of 1 with cyclic ketones (cyclopentanone and cyclohexanone) lead to Ti(iii) complexes [{(ArN[double bond, length as m-dash]C(Me)CHC(Me)[double bond, length as m-dash]NAr)((CH₂)₄CO)}Ti(Cl){PtBu₂-P(SiMe₃)((CH₂)₄CO)}] (10) and [{(ArN[double bond, length as m-dash]C(Me)CHC(Me)[double bond, length as m-dash]NAr)((CH₂)₅CO)}Ti(Cl){PtBu₂-P(SiMe₃)((CH₂)₅CO)}] (11), which are formed via the successive insertion of two molecules of ketone to one molecule of 1. The stability investigation of complexes 10 and 11 in a polar solvent (THF) revealed that under these conditions, the complexes decompose, resulting in titanium(iii) complexes with aldol condensation products and the expected phosphanylphosphaalkenes (CH₂)₄C[double bond, length as m-dash]P-PtBu₂ (10a) and (CH₂)₅C[double bond, length as m-dash]P-PtBu₂ (11a). In the reaction of 1 with cycloheptanone, only the Ti(iii) complex with the aldol condensation product [^MeNacNacTi(Cl){OC(CH₂)₆}CH(C[double bond, length as m-dash]O)(CH₂)₅] (12) was isolated. The structures 3, 5, 8, 10, 11, 11b and 12 were characterized by X-ray spectroscopy, while all the phosphanylphosphaalkenes were characterized by 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 (Ph)tBuP-P(SiMe3)Li·3THF with [(PNP)TiCl2] and [MeNacNacTiCl2·THF]: synthesis of first PNP titanium(iv) complex with the phosphanylphosphinidene ligand [(PNP)Ti(Cl){η2-P-P(Ph)tBu}]

Herein, the lithium derivative of diphosphane, (Ph)tBuP-P(SiMe3)Li (1), is isolated for the first time and investigated in reactions with β-diketiminate (MeNacnac- = [Ar]NC(Me)CHC(Me)N[Ar]; Ar = 2,6-iPr2C6H3) and PNP-pincer (PNP = N[2-PiPr2-4-methylphenyl]2) Ti(iii) complexes. The β-diketiminate titanium(iii) complex containing the phosphanylphosphido ligand [MeNacNacTi(Cl){η2-P(SiMe3)-P(Ph)tBu}] (2) is prepared via the reaction of [MeNacNacTiCl2·THF] with (Ph)tBuP-P(SiMe3)Li in toluene solution with good yield and purity. The corresponding titanium(iv) complex involving the phosphanylphosphinidene ligand [MeNacNacTi(Cl){η2-P-P(Ph)tBu}] (3) is synthesized via the oxidation of complex (2) with [iBu3PAgCl]4. Interestingly, an analogous PNP titanium(iv) complex, [(PNP)Ti(Cl){η2-P-P(Ph)tBu}] (4), is obtained in the reaction of [(PNP)TiCl2] with (Ph)tBuP-P(SiMe3)Li in toluene solution and a 1 : 1 molar ratio instead of the expected titanium(iii) complex with the phosphanylphosphido ligand. The solid-state structures of (Ph)tBuP-P(SiMe3)Li·3THF (1), [MeNacNacTi(Cl){η2-P(SiMe3)-P(Ph)tBu}] (2), [MeNacNacTi(Cl){η2-P-P(Ph)tBu}] (3) and [(PNP)Ti(Cl){η2-P-P(Ph)tBu}] (4) are determined by single-crystal X-ray diffraction, which reveals that in all obtained complexes, both the phosphanylphosphinidene (Ph)tBuP-P and phosphanylphosphido (Ph)tBuP-P(SiMe3) ligands are bidentate-coordinated to the metal center.