The bidentate ligand 2,11‐bis(diphenylphosphinomethyl)benzo[c]phenanthrene (1) was synthesized from 2,11‐dimethyl‐benzo[c]phenanthrene (3) via the corresponding bromomethyl derivative 9. 3 was obtained from the cyclization with boron trifluoride etherate of 1,1‐di‐(p‐methylphenethyl)‐epoxyethane (7), which was prepared from 1,5‐di(p‐tolyl)‐pentan‐3‐one (6).

It is shown that the ligand 2,11‐bis(diphenylphosphinomethyl)benzo[c]phenanthrene (1) reacts with nickel(II), palladium(II) and platinum(II) substrates giving either exclusively, or predominantly, mononuclear complexes of the type trans‐[MX2(1)] in which the organic ligand spans trans‐positions. It is further shown that the spectroscopic properties which are mainly associated with metal and donor atoms in complexes of this type are closely related to those of the corresponding square planar complexes of the type trans‐[MX2(Ph2PCH2Ph)2].

No abstract