Two phosphonite ligands bearing the highly sterically demanding 2,6-bis (2,6-dimethylphenyl)phenyl group (Ar
Xyl2),
PArXyl2(OPhNO2)2 and
PArXyl2(OPhNO2,Me)2, were prepared from the parent dihalophosphines PAr
Xyl2
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Two phosphonite ligands bearing the highly sterically demanding 2,6-bis (2,6-dimethylphenyl)phenyl group (Ar
Xyl2),
PArXyl2(OPhNO2)2 and
PArXyl2(OPhNO2,Me)2, were prepared from the parent dihalophosphines PAr
Xyl2X
2 (X = Cl, Br) and the corresponding phenols, 4-nitrophenol and 4-nitro-2,6-dimethylphenol, respectively. DFT methods were used to examine their structural features and to determine three steric descriptors, namely the Tolman cone angle, the percentage of buried volume, and the percentage of the coordination sphere protected by the ligand. A comparison with the related terphenyl phosphines is also provided. Reactions of
PArXyl2(OPhNO2)2 and
PArXyl2(OPhNO2,Me)2 with several Pt(II) precursors were investigated, revealing a high tendency of both phosphonites to undergo C-H activation processes and generate five- or six-membered cyclometalated structures. The coordination chemistry of the new ligands was explored with isolation, among others, of three carbonyl complexes,
1-3∙CO, and the triphenylphosphine adduct
3∙PPh3. X-ray diffraction methods permitted the determination of the solid-state structures of the mononuclear methyl carbonyl complex
1∙CO, the dinuclear chloride-bridged complex
2 and the doubly cyclometalated complex
3∙SMe2, including the conformations adopted by the ligands upon coordination. All of the new compounds were characterized by multinuclear NMR spectroscopy in solution.
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