1410026-59-3Relevant academic research and scientific papers
Nickel(II) complexes containing a pyrrole-diphosphine pincer ligand
Venkanna, Gopaladasu T.,Ramos, Teresa Virginia M.,Arman, Hadi D.,Tonzetich, Zachary J.
, p. 12789 - 12795 (2013/02/22)
A new pincer ligand, (P2PhPyr)-, based on the anion of 2,5-bis[(diphenylphosphino)methyl]pyrrole has been prepared in four steps from pyrrole. The ligand undergoes oxidation to diphosphine oxide under ambient conditions and was therefore isolated as its borane adduct, H(P 2PhPyr)·2BH3 (2). Delivery of the ligand to nickel(II) was accomplished by the direct reaction of NiCl2 with 2 in the presence of Et2NH to afford [NiCl(P2 PhPyr)]. Salt metathesis reactions of the chloro complex afford new compounds including [Ni(CH3)(P2PhPyr)] and [Ni(NCCH3)(P2PhPyr)](OTf). In all cases, the ligand gives rise to diamagnetic square-planar complexes, which have been fully characterized in solution and the solid state. All complexes examined display an irreversible oxidation to nickel(III) according to cyclic voltammetry. Reduction of the chloro complex in dichloromethane results in an electrocatalytic process, whereas reduction in tetrahydrofuran leads to the irreversible formation of a nickel(I) species.
Pyrrole-based new diphosphines: Pd and Ni complexes bearing the pnp pincer ligand
Kumar, Shanish,Mani, Ganesan,Mondal, Sukanta,Chattaraj, Pratim Kumar
, p. 12527 - 12539 (2013/01/15)
A new class of diphosphine PNP pincer ligand, 2,5- bis(diphenylphosphinomethyl)pyrrole 2, was synthesized by the reaction between Ph2PH and 2,5-bis(dimethylaminomethyl)pyrrole in 90% yield. The analogous reaction of Ph2PH with 1,9-bis(dimethylaminomethyl) diphenyldipyrrolylmethane readily afforded a PNNP type diphosphine ligand, 1,9-bis(diphenylphosphinomethyl)diphenyldipyrrolylmethane 5 in 92% yield. These phosphine compounds were oxidized with H2O2 and S 8 to give the corresponding phosphoryl and thiophosphoryl compounds 6-9 in very good yields. The reaction of the PNP pincer ligand 2 with [PdCl 2(PhCN)2] in the presence of Et3N afforded the mononuclear Pd(II) complex, [PdCl{C4H2N-2,5-(CH 2PPh2)2-κ3PNP}] 10 in 87% yield. Conversely, treatment of 2 with [PdCl2(PhCN)2] in the absence of Et3N gave the dinuclear Pd(II) complex [Pd 2Cl4{μ-C4H3N-2,5-(CH 2PPh2)2-κ2PP}2], the structure which is proposed based on the spectroscopic data. When 2 was treated with Pd(0) precursor [Pd2(dba)3]·CHCl 3 the dinuclear Pd(I) complex [Pd2{μ-C 4H2N-2,5-(CH2PPh2) 2-κ2PN,κ1P}2], 12, was obtained in 23% yield. The formation of complex 12 is solvent dependent, which transforms into complex 10 in CDCl3 as studied by variable temperature 1H and 31P NMR methods. Treatment of 2 with [Ni(OAc)2]·4H2O gave the mononuclear Ni(II) pincer complex [Ni(OAc){C4H2N-2,5-(CH2PPh 2)2-κ3PNP}], 13, which upon treatment with an excess of LiCl or LiBr or KI afforded the respective halide ion substituted Ni(II) complexes, [NiX{C4H2N-2,5-(CH 2PPh2)2-κ3PNP}] (X = Cl, Br, and I), 14-16, in very good yields. The structures of 5, 2,5- bis(diphenylphosphorylmethyl)pyrrole 6, 10, 12, and 14-16 were determined by the single crystal X-ray diffraction method. In the structure of 12, two short contacts between the diagonally positioned Pd and P atoms are observed. To understand these weak interactions, density functional theory (DFT) calculations were done and an interaction MO diagram is presented.
A readily accessible PNP pincer ligand with a pyrrole backbone and its NiI/II chemistry
Grueger, Nora,Wadepohl, Hubert,Gade, Lutz H.
, p. 14028 - 14030 (2013/01/15)
The novel chelating PNP pincer ligand 2,5-bis((diphenylphosphino)methyl)- 1H-pyrrole (1) was prepared and its nickel coordination chemistry explored. The reaction with Ni(COD)2 led to a diamagnetic dinuclear nickel(i) complex (4) which was also
