Complexes comprising ‘dangling’ phosphorus arms and tri(hetero)metallic butenynyl moieties

Trans -RuCl 2 (PP 3 ) 2 ( 1a ) (PP 3 = tris[2-(diphenylphosphino)ethyl]phosphine) was prepared by reaction of RuCl 2 (PPh 3 ) 3 with 2 eq. PP 3 . Through coordination of two potentially tetradentate ligands in a bidentate arrangement, four uncoordinated phosphine moieties remain readily available for subsequent reaction. This is demonstrated through their facile oxidation with hydrogen peroxide, providing trans- RuCl 2 (PP[P O] 2 ) 2 ( 1b ) (PP[P O] 2 = bis[2-(diphenylphosphine oxide)ethyl][2-(diphenylphosphino)ethyl]phosphine). Whilst chloride abstraction reactions from 1a appear slow (typical for trans dichlorides), cis- RuCl 2 (PP 3 ) is shown to react rapidly with ethynylferrocene under ‘Dixneuf’ conditions (CH 2 Cl 2 , NaPF 6 , NEt 3 ), providing the tri(hetero)metallic butenynyl complex [(PP 3 )Ru(η 3 –FcC 3 CHFc)]PF 6 ( 2 , Fc = ferrocenyl). The pendant groups of 1a-b offer great potential for future coordination studies (for example, to prepare mixed transition metal/lanthanide materials), whereby the facile synthetic route to 2 suggests a path towards examination of complex mixed-valence systems comprising multiple redox-active centres.