Synthesis of ligands based on naphthalene peri-substituted by Group 15 and 16 elements and their coordination chemistry

The synthetic aspects of chemistry of ligands based on naphthalene peri-substituted by heavier Group 15 elements (P, As, Sb, Bi) or Group 16 elements (S, Se, Te) are discussed in this review. An overview of coordination chemistry of these ligands is also given. In general, the area is dominated by bis(phosphines) Nap(PR₂)₂ and dithiolates Nap(SR)₂ (Nap = naphthalene-1,8-diyl), and most of the ligands act with chelating rigid C₃-backbones. Whilst all known bis(phosphine) complexes with Ni, Pd and Pt contain unmodified Nap(PR₂)₂ moieties, the reactions with a variety of metal carbonyls sometimes result in P–C bond cleavage within the ligand. A range of gold complexes with Nap(PR₂)₂ ligands have been investigated for material applications. NapP₂ ligands other than phosphines are also described, these include 1,2-diphosphaacenaphthenes, bis(phosphonites) and bis(phosphine oxides). Group 16 peri-dichalcogenolates used as ligands include NapS₂, NapSe₂ and NapSSe systems, but no tellurium congeners. Heterodentate ligands discussed in this review include those with NapPN, NapPO, NapPS, NapPF, NapPC and NapSN motifs. Ligands with heavier Group 15 donor atoms (NapAs₂, NapSb₂) are also reported. All possible oxides of the dithioles (monooxide to tetraoxide) as ligands are also discussed. Areas of interest for further work are outlined.