Phospha Derivatives of Tris(2-aminoethyl)amine (tren) and Tris(3-aminopropyl)amine (trpn): Synthesis and Complexation Studies with Group 4 Metals

Abstract

The N,N′,N″-triphenyl-substituted derivative of tris(2-aminoethyl)phosphine (Ph 3 -phospha-tren, P-(CH 2 CH 2 NHR) 3 , R = Ph) and four derivatives of the related t r i s ( 3 -a m i n o p r o p y l ) p h o s p h i n e ( p h o s p h at r p n , P-(CH 2 CH 2 CH 2 NHR) 3 , R = i Pr, t Bu, Si t BuMe 2 , Ph) have been synthesized in addition to the parent phospha-trpn. Out of these ligand systems, only the N,N′,N″-triphenyl-substituted phosphatrpn derivative P(CH 2 CH 2 CH 2 NHPh) 3 was found to be suitable for coordination to group 4 metals. For titanium, zirconium, and hafnium, the C 3 -symmetric endo-P-configured dimethylamido complexes Ph [PN 3 ]M(NMe 2 ) of the former ligand have been prepared and converted into the corresponding triflates Ph [PN 3 ]M(OTf). Starting from these triflates, the benzyl complexes Ph [PN 3 ]M(Bn) (M = Ti, Zr, Hf) have been obtained via reaction with Bn 2 Mg(THF) 2 . In case of titanium, the benzyl species Ph [PN 3 ]Ti(Bn) is prone to thermal elimination of toluene, which results in the formation of a cyclometalated species. These findings are discussed in context with the very few group 4 trisamidophosphine complexes that have been reported earlier.

Diamidophosphines with six-membered chelates and their coordination chemistry with group 4 metals: development of a trimethylene-methane-tethered [PN2]-type “molecular claw”

“…In agreement with the above mentioned expectation, the propylene-and benzylene-linked ligands, pr [NPN]H 2 and bn [NPN] H 2 , were readily synthesised following an adaption of our previously reported experimental procedure for the preparation of related triamidophosphine scaffolds (see Scheme S1 in the ESI †). 58,59 Both ligands were obtained in gram quantities and high purities, which allowed for their direct use to prepare the envisioned group 4 complexes shown in Chart 2.…”

Double-headed nanosystems for oral drug delivery

“…21 Tris(2-aminoethyl) amine (TREN), a flexible C 3 symmetric linker, has been extensively utilized in co-ordination chemistry as tri-or tetradentate ligand for various metal ion interactions and sensor based applications. [22][23][24][25] It has been reported that the flexibility of TREN assisted in self-assembly of the collagen mimetic scaffold due to effective adjusting of the three peptide chains to form triple helical packing. 26 The TREN binding site in the artificial L-serine derivative based metallocatalyts has been reported to act as allosteric regulation sites due to conformation change upon metal binding.…”

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

“…That nitrido complexes (XylN t Bu) 3 Mo≡N and Mes 3 Mo≡N of Cummins et al and Floriani et al, which both lack trans ‐donor functionality, were found to be catalytically inactive is in line with this argument. 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 .…”