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Synthetic methods for the coordination of the monoanionic bis[2-(diisopropylphosphino)-4-methylphenyl]amido (PNP) ligand framework to the cerium(III) cation have been developed and applied for the isolation of a series of {(PNP)Ce} and {(PNP)2Ce} type complexes. The structures of the complexes were studied by X-ray diffraction and multinuclear NMR spectroscopy. We found that the cerium(III) ion can induce the elimination of one of the iPr groups at phosphorus to yield a new dianionic PNP tridentate framework (PNP- iPr) featuring a phosphido-donor functionality, which is bound to the cerium ion with the shortest known Ce−P bond of 2.7884(14) Å for molecular compounds. The reaction of the complex [(PNP)Ce{N(SiMe3)2}2] ( 1) with Ph2CO gave the Ce-bound product of C−C coupling, -N(SiMe3)SiMe2CH2-CPh2O−, through the C−H bond activation of a SiMe3 group. 31P NMR spectroscopy was used to estimate the presence of a vacant coordination position at the cerium ion in the CeIII-PNP complexes by the examination of the δ(31P) shift recorded both in non-polar (C6D6) and polar ([D8]THF) solvents. Moreover, 31P NMR spectroscopy was also found to be a useful tool for the estimation of the Ce−P bond distances in {(PNP)CeIII} and {(PNP)2CeIII} systems. Electrochemical and computational studies for 1 and its lanthanum analogue containing a redox-innocent metal center revealed the stabilization of the CeIII oxidation state by the PNP ligand. [ABSTRACT FROM AUTHOR]

We report the synthesis and structure of a series of tantalum(V) complexes having the trimethylsilylimide moiety and using as ancillary support the pincer ligand PNP (PNP − = N[2-P i Pr 2 -4-methylphenyl] 2 ). Via transmetallation of Li(PNP) with Cl 3 (py) 2 Ta N{SiMe 3 } (py = pyridine), the precursor complex (PNP)Ta N{SiMe 3 }Cl 2 ( 1 ) could be prepared in 94% isolated yield. Attempts to promote FSiMe 3 elimination when 1 was treated with FSnMe 3 resulted in mixtures from which the salt-like product [{(PNP)Ta N{SiMe 3 }} 2 (μ 2 -F) 3 ][Me 3 ClSn(μ 2 -X)SnClMe 3 ] ( 2 ) (X − = F or Cl) was structurally identified. However, conducting the reaction with NaOAr (Ar = 2,6- i Pr 2 C 6 H 3 ) resulted in clean formation to (PNP)Ta N{SiMe 3 }(OAr)Cl ( 3 ) in 79% isolated yield, and when 3 was mixed with FSnMe 3 , the fluoride-imide complex (PNP)Ta N{SiMe 3 }(OAr)F ( 4 ) and ClSnMe 3 were formed cleanly. Attempts to promote FSiMe 3 elimination in 4 thermally and photochemically did not yield the desired nitride (PNP)Ta N(OAr). Complexes 1 – 4 were characterized by single-crystal X-ray diffraction studies and in the case of complexes 1 , 3 and 4 a variety of multinuclear NMR studies are presented and discussed. [ABSTRACT FROM AUTHOR]

We report the synthesis and structure of a titanium(iv) benzophenone adduct bearing a terminal oxo ligand, (PNP)Ti = O(OTf)(OCPh2) (PNP− = N[2-PiPr2-4-methylphenyl]2) (2). Complex 2 is readily synthesized in 71% yield from the previously reported titanium alkylidene (PNP)Ti=CHtBu(OTf) (1) and two equivalents of benzophenone, by extruding the olefin Ph2C=CHtBu. Treatment of benzophenone adduct 2 with a bulky aryloxide salt results in formation of (PNP)Ti=O(OAr) (3) (OAr− = 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide), concurrent with salt elimination and displacement of the benzophenone. Complexes 2 and 3 were characterized by single-crystal X-ray diffraction and a variety of spectroscopic techniques, including NMR, UV-Vis-NIR spectroscopies, and TD-DFT calculations. [ABSTRACT FROM AUTHOR]

We report the synthesis of a gallium complex incorporating redox-active pyridyl nitroxide ligands. The (pyNO−)2GaCl complex was prepared in 85% yield via a salt metathesis route and was characterized by 1H and 13C NMR spectroscopies, X-ray diffraction, and theory. UV–Vis absorption spectroscopy and electrochemistry were used to access the optical and electrochemical properties of the complex, respectively. Our discussion focuses primarily on a comparison of the gallium complex to the corresponding aluminum derivative and shows that although the complexes are very similar, small differences in the electronic structure of the complexes can be correlated to the identity of the metal. [ABSTRACT FROM AUTHOR]

The coordination chemistry of complexes featuring a PNP ligand framework and the redox active lanthanide ion, cerium(III), was initiated. The cerium(III) ion induced the transformation of one of the phosphino donor arms at a parent PNP ligand into a new phosphido functionality. The Ce−PNP systems were also employed for C−C bond‐forming reactions and the molecular structures of Ce−PNP complexes were studied both in solution and in the solid state. More information can be found in the Full Paper by O. V. Ozerov, E. J. Schelter et al. on page 17923. [ABSTRACT FROM AUTHOR]