Metal-Template-Directed Synthesis of Diphosphorus Compounds through Intramolecular Phosphinidene Additions

Heating the nonchelating cis‐bis‐7‐phosphanorbornadiene‐[Mo(CO)4] complex (13) results in the thermal decomposition of one of the 7‐phosphanorbornadiene groups. The phosphinidene thus generated adds intramolecularly to a C=C bond of the other ligand to give the novel diphosphorus complex 14. This reaction constitutes a metal‐template‐directed synthesis. Likewise, the intramolecular phosphinidene addition to the C=C bond of a Mo‐phospholene ligand affords the diphos complex 18. Its crystal structure exhibits an extremely small P‐Mo‐P bite‐angle for a five‐membered chelate ring. The similar intramolecular 1,2‐addition to a C=C bond of a phosphole ligand gives a highly strained, unstable intermediate product. Scission of its P−Mo bond generates a free coordination site, which is then occupied by either CO or a phosphole to yield complexes 22 and 23, respectively. The analogous intermolecular addition of [PhPW(CO)5] to a [phosphole‐W(CO)5] complex gives the di‐[W(CO)5] complexed adduct 28. The directing effect of the metal on the intra‐ and intermolecular additions is discussed. New diphos compounds are generated (see figure) from the intramolecular addition of a phosphinidene to organophosphorus ligands of the nonchelating cis‐7‐phosphanorbornadiene‐[MoR(CO)4] complex. The directing effect of the metal on the intra‐ and intermolecular additions is discussed.