Functional Short-Bite Ligands: Synthesis, Coordination Chemistry, and Applications of N-Functionalized Bis(diaryl/dialkylphosphino)amine-type Ligands

Abstract

The aim of this review is to highlight how the diversity generated by N-substitution in the well-known short-bite ligand bis(diphenylphosphino)amine (DPPA) allows a fine-tuning of the ligand properties and offers a considerable scope for tailoring the properties and applications of their corresponding metal complexes. The various N-substituents include nitrogen-, oxygen-, phosphorus-, sulfur-, halogen-, and silicon-based functionalities and directly N-bound metals. Multiple DPPA-type ligands linked through an organic spacer and N-functionalized DRPA-type ligands, in which the PPh2 substituents are replaced by PR2 (R = alkyl, benzyl) groups, are also discussed. Owing to the considerable diversity of N-functionalized DPPA-type ligands available, the applications of their mono- and polynuclear metal complexes are very diverse and range from homogeneous catalysis with well-defined or in situ generated (pre)catalysts to heterogeneous catalysis and materials science. In particular, sustained interest for DPPA-type ligands has been motivated, at least in part, by their ability to promote selective ethylene tri- or tetramerization in combination with chromium. Ligands and metal complexes where the N-substituent is a pure hydrocarbon group (as opposed to N-functionalization) are outside the scope of this review. However, when possible, a comparison between the catalytic performances of N-functionalized systems with those of their N-substituted analogs will be provided.

Selective ethylene oligomerization with in‐situ‐generated chromium catalysts supported by trifluoromethyl‐containing ligands

“…When the influence of the reaction conditions on the catalytic behavior was systematically investigated with 3o/Cr(acac) 3 , both the selectivity and catalytic activity were dramatically influenced by the choice of the activator and solvent, as summarized in Table 2. First, under typical ethylene oligomerization conditions, on activation with a toluene solution of MAO (10 wt %), ethylene oligomerization with 3o/Cr(acac) 3 resulted in a nonselective distribution of oligomers including 66 mol % of C 10 -C 40 (entry 7). Various examples are reported where the presence of toluene poisons the selective ethylene oligomerization catalyst and results in a nonselective distribution of ethylene oligomers.…”

“…The combination of nitrogen (N) and phosphorus (P) donor atoms within an ancillary ligand system for selective oligomerization has been expanded since the discovery of chromium bis(diphenylphosphino)amine . Although a variety of amine groups on the aminophosphine ligands were extensively studied for selectivity control, previous studies on the modification of diarylphosphine parts are quite limited . One such study, by Wass and coworkers , claimed that the ortho ‐methoxy‐substituted aryl group on bis(diarylphosphino)amine played an important role in the ethylene trimerization and is essential for catalytic activity .…”

Binuclear Copper(I) Borohydride Complex Containing Bridging Bis(diphenylphosphino) Methane Ligands: Polymorphic Structures of [(µ2-dppm)2Cu2(η2-BH4)2] Dichloromethane Solvate

“…The concept of cooperative catalytic effects [1] in multinuclear transition metal systems led to the broad development and extensive investigation of the chemistry of transition metal complexes, bearing "short-bite" ligands that are able to lock two or more metallocenters in close proximity [2][3][4][5][6][7]. Such compounds are of great interest due to their catalytic activity including the transformation of small molecules on metal centres [8,9], they can also be used as synthetic models of enzyme action [10][11][12].…”

Immobilization of [Pd{(Ph2P)2N(CH2)3Si(OCH3)3‐κP,P'}X2] (X=Cl, Br) onto Montmorillonite: Investigating their Performance as Homogeneous or Heterogenized Suzuki‐Miyaura Catalysts

“…[4] The bis(phosphino)amine type of ligands, (R 2 P) 2 N(R'), in the following referred to as (P,P), constitute a well explored family of bidentate phosphines, affording a large number of transition metal complexes, [5] which are active catalysts in various types of reactions, as recently reviewed. [6] In addition to their catalytic properties, ligands of this type have been employed for the synthesis of dinuclear complexes as analogues of the Fe-only hydrogenase's active site. [7] A dinuclear complex of this type, [7c] along with a series of recently reported mononuclear complexes [Fe(S 2 C 6 H 4 )(P,P)(CO)], [8] are active electrocatalysts for the Hydrogen Evolution Reaction (HER).…”