The Synthesis of New Phosphonium Cyclopentadienylides and Fluorenylides and Several Derived Metal Complexes

In a search for ambidentate chelating phosphane/ylide ligands two [(diphenylphosphino)alkyl]‐diphenylphosphonium fluorenylides 2a , b and 1,3‐propanediylbis(diphenylphosphonium fluorenylide) ( 5 ) were synthesized from α,ω‐bis(diphenylphosphino)alkanes (C 6 H 5 ) 2 P[CH 2 ] n P(C 6 H 5 ) 2 , n = 1–3, and 9‐bromofluorene, via the parent phosphonium salts. [2‐(Diphenylphosphino)‐ethyl]diphenylphosphonium cyclopentadienylide ( 1b ) could only be obtained in low yield. – Ylide 2a forms tetracarbonylmetal complexes with (CO) 3 W(NCCH 3 ) 3 and Cr(CO) 6 , which are assigned a chelating five‐membered ring structure, the cyclopentadienyl ring being in an unusual monohapto state of bonding ( 6a , b ). A by‐product of the Cr(CO) 6 reaction is identified as the Cr(CO) 3 complex 7 with the metal attached to one benzene ring of the fluorene system. 1:1 complexes of PdCl 2 and PtCl 2 with 2a are again assigned a chelate monohapto‐fluorene mode of complexation ( 10a , b ), but with 2b an ionic product 13 is encountered. HgCl 2 forms 2:1 and 3:2 complexes with 2a , for which only tentative formulae can be proposed (e.g. 14 ). AuCl forms an ionic 1:1 complex 15 with the bis‐fluorenylide 5 .