Platinum(II) Complexes of P‐Chiral 1, 8‐Bis(diorganophosphino)naphthalenes; Crystal Structures of dmfppn,rac‐[PtCl2(dmfppn)], and rac‐[PtCl2(dtbppn)] (dmfppn = 1, 8‐di(methyl‐pentafluorophenylphosphino)naphthalene and dtbppn = 1, 8‐di(tert‐butylphenylphosphino)naphthalene)

The reaction of 1, 8‐dilithionaphthalene 2 , with 2 equivalents of rac‐Me(C₆F₅)PCl, gave a 6 : 1 mixture of rac‐ and meso‐1, 8‐di(methyl‐pentafluorophenylphosphino)naphthalene (dmfppn, rac‐ 3h and meso‐ 3h ), but no reaction was observed when the sterically crowded rac‐tBu(C₆F₅)PCl was used. In ³¹P NMR experiments, rac‐ 3h and mmeso‐ 3h exhibited characteristic signals (virtual quintets), which indicate that there is significant coupling through space (³J_PF + ⁷ J_PF ≈ 15 Hz). Compound rac‐ 3h was isolated by fractional crystallisation and treated with aqueous H₂O₂ to yield the corresponding bis‐phosphine dioxide, rac‐ 7h . In contrast to rac‐ 3h , there was no sign of through‐space coupling in rac‐ 7h , which again illustrates that the latter operates via the lone pairs at phosphorus. Platinum(II) complexes were prepared from the new, P‐chiral chelate rac‐ 3h , and the related ligand 1, 8‐di(tert‐butylphenylphosphino) naphthalene (rac‐dtbppn, rac‐ 3e ). All isolated new compounds were characterised by multinuclear NMR and IR spectroscopy, mass spectrometry, and elemental analysis. Single‐crystal X‐ray structure determinations were performed for rac‐dmfppn (rac‐ 3h ), rac‐PtCl₂(dtbppn)] (rac‐ 17e ), and rac‐PtCl₂(dmfppn)] (rac‐ 17h ). rac‐ 3h displays crystallographic twofold symmetry. In rac‐ 17h , the electron‐withdrawing effect of the C₆F₅ groups causes a shortening of the P_t—P bond to ca. 220 pm (cf. 223 pm in rac‐ 17e ).