Diamagnetic molybdenum nitride complexes supported by diligating tripodal triamido-phosphine ligands as precursors to paramagnetic phosphine donors

Abstract

The reaction of the ligand precursors P[CH2NHAr(R)]3 () with (Me2N)3Mo[triple bond, length as m-dash]N generated the complexes P(CH2NAr(R))3Mo[triple bond, length as m-dash]N (), where Ar(R) = 3,5-(CH3)2C6H3 (), Ph (), and 3,5-(CF3)2C6H3 (), with (Me2N)3Mo[triple bond, length as m-dash]N generated the complexes P(CH2NAr(R))3Mo[triple bond, length as m-dash]N (). Complex was obtained in poor yield, due to the formation of P(CH2N-3,5-(CF3)2C6H3)2(CH2NH-3,5-(CF3)2C6H3)(NMe2H)(NMe2)Mo[triple bond, length as m-dash]N () as the major product. Reaction of with VMes3THF generated the paramagnetic complexes P(CH2NAr(R))3Mo(μ-N)V(Mes)3 (). The reaction of with Ni(acac)2 generated the Ni(0) complexes Ni[P(CH2NAr(R))3Mo[triple bond, length as m-dash]N]4 () in poor yield. These complexes were synthesized in higher yields from the reaction of with Ni(COD)2, where COD = 1,5-cyclooctadiene. Reaction of either with V(Mes)3THF or with Ni(COD)2 generated the paramagnetic nonanuclear complex Ni[P(CH2NAr(R))3Mo(μ-N)VMes3]4 ().

Cyclometalated titanium and zirconium complexes stabilised by a new silylmethylene-linked tetradentate triamidophosphine

“…33 Thus, the preparation of the above mentioned long-term target complexes was considered challenging using these two ligands. For the methylene-linked triamidophosphine P(CH 2 NHAr) 3 , similar exo-P-configured complexes were observed, [34][35][36] while endo-P-configurations were found for triamidophosphine complexes incorporating three six-membered chelates. 31,37,38 In the latter systems, however, endocyclic deprotonations of the employed linkers were observed for titanium alkyl derivatives, which questioned the suitability of these systems as substitutes for the actually desired phospha-tren complexes.…”

Pitfalls and Limitations in Group 6 Triamidophosphane Chemistry: Cage‐Closure Restrictions in Square‐Pyramidal Nitrido Complexes and Degradation via Spiro‐[4.4]‐λ5‐Amidophosphorane Formation

“…With the two phospha‐ tren ligands P(CH 2 CH 2 NHR) 3 (R = SiMe 3 , Ph) reported to date, however, no well‐defined metal complexes have been isolated . Therefore, closely related systems have been targeted over the past years, and the N , N′ , N′′ ‐triaryl‐substituted methylene‐linked triaminophosphanes P(CH 2 NHR) 3 (R = Ph, Xyl, C 6 F 5 ) were recently shown to react productively with (Me 2 N) 3 Mo≡N . In the resulting closed‐cage complexes II , however, the lone pairs of the phosphanes were found to point away from the central molybdenum atoms ( exo ‐ P configuration, see Scheme ), which allowed for the use of these complexes as building blocks for the construction of heteromultimetallic assemblies , .…”

“…Therefore, closely related systems have been targeted over the past years, and the N , N′ , N′′ ‐triaryl‐substituted methylene‐linked triaminophosphanes P(CH 2 NHR) 3 (R = Ph, Xyl, C 6 F 5 ) were recently shown to react productively with (Me 2 N) 3 Mo≡N . In the resulting closed‐cage complexes II , however, the lone pairs of the phosphanes were found to point away from the central molybdenum atoms ( exo ‐ P configuration, see Scheme ), which allowed for the use of these complexes as building blocks for the construction of heteromultimetallic assemblies , . In the absence of additional metal centers, the minor lobe of the phosphane lone pair still seems to interact with the metal center within the cage, but it remains unclear whether this interaction alters the reactivity of the apical nitrido ligand.…”

“…In the resulting closed‐cage complexes II , however, the lone pairs of the phosphanes were found to point away from the central molybdenum atoms ( exo ‐ P configuration, see Scheme ), which allowed for the use of these complexes as building blocks for the construction of heteromultimetallic assemblies , . In the absence of additional metal centers, the minor lobe of the phosphane lone pair still seems to interact with the metal center within the cage, but it remains unclear whether this interaction alters the reactivity of the apical nitrido ligand. Nevertheless, these systems are so far closest to the envisioned target, namely, a molybdenum triamidophosphane complex having a trans ‐P–Mo≡N array (cf.…”