Complexes of Ni(II) with triphosphine‐phosphite ligand P(OCH 2 PPh 2 ) 3 : syntheses, structures, and electronic properties

Ionic complexes [(κ 4 −PP 3 )P(OCH 2 PPh 2 ) 3 NiX]BF 4 ( 2 (X=Cl) and 3 (X=Br)) were formed when P(OCH 2 PPh 2 ) 3 ligand ( 1 ) was reacted with mixtures of salts NiX 2 /Ni(BF 4 ) 2 (X=Cl or Br). Single crystal X‐ray characterizations performed on complexes 2 and 3 established that metal centers are in pseudo‐trigonal bipyramidal ligand geometries formed by the phosphorus centers from coordinated 1 and the halide ligand. Reactions of 1 with other nickel(II) salts (acetate, nitrate or tetrafluoroborate) proceeded in 2 : 1 (ligand‐salt) ratio yielding complex 4 , [(κ 3 −PP 2 )(( − O−P)(OCH 2 PPh 2 ) 2 )(κ 2 −PP)( − O−P)(OCH 2 PPh 2 )(OCH 2 P(=O)Ph 2 )Ni]. The formation of this complex required hydrolysis of one of the P−O ester bonds in ligand P(OCH 2 PPh 2 ) 3 thus forming O‐anionic phosphite/diphosphine fragment [ − O−P(OCH 2 PPh 2 ) 2 ]. One of such fragments is coordinated to the metal center as a tridentate (κ 3 −PP 2 ) ligand, whereas the other is in bidentate (κ 2 −PP) coordination via phosphorus centers of the − O‐P‐OCH 2 PPh 2 chelating pocket; the remaining ‐OCH 2 P(=O)Ph 2 arm is P‐oxidized and uncoordinated. Nickel center in 4 is in distorted trigonal‐bipyramidal geometry, with O‐anionic‐phosphite groups coordinated at the axial positions, and the three ‐PPh 2 groups located in the equatorial plane. Compounds 2 – 4 were characterized by multinuclear NMR spectroscopy, elemental analyses, electron absorption spectroscopy, cyclic voltammetry, and single crystal X‐ray crystallography. Their electronic structures were also investigated by DFT methods.