Synthesis, Characterization and Electrochemical Properties of 4,5‐Diazafluoren‐9‐yl or Fluoren‐9‐yl Terminated Homobimetallic Ruthenium and Osmium Allenylidene, Alkynyl‐Allenylidene Complexes

Abstract

A variety of rigid ruthenium and osmium allenylidene [M 1 Cl(PP) 2 ＝ C ＝ C(4,5-diazafluoren-9-yl)-{M 2 (CHC(PPh 3 )CHC(PPh 3 )Cl 2 (PPh 3 ) 2 }][PF 6 ] 3 (4a: M 1 ＝Os, M 2 ＝Os, PP＝dppm; 4b: M 1 ＝Os, M 2 ＝Ru, PP＝ dppm; 4c: M 1 ＝Ru, M 2 ＝Os, PP＝dppe; 4d: M 1 ＝Ru, M 2 ＝Ru, PP＝dppe), ruthenium alkynyl-allenylidene complexes trans-[(dppe) 2 Ru(C≡CPh)Ru＝C＝C(R)][PF 6 ] (6a: R＝fluoren-9-yl; 6b: R＝4,5-diazafluoren-9-yl), trans-{(dppe) 2 [＝C＝C(fluoren-9-yl)]Ru(C≡C-R-C≡C)Ru[(＝C＝C(fluoren-9-yl)(dppe) 2 ]} [PF 6 ] 2 (8a, R＝ 1,4-phenylene; 8b, R＝1,3-phenylene) terminated by 4,5-diazafluoren-9-yl and fluoren-9-yl group have been prepared. These allenylidene complexes were derived from 9-ethynyl-9-fluorenol and 9-hydroxy-9-ethynyl-4,5-diazafluorene in the presence of cis-OsCl 2 (dppm) 2 and cis-RuCl 2 (dppe) 2 . The respective products have been fully characterized by 1 H, 13 C, 31 P NMR spectrometry, IR spectrometry, elemental analysis, and UV/Vis spectrophotometry. Moreover, electrochemical studies reveal that the dinuclear complexes display a quasi-reversible redox behavior and a moderate electronic communication between the two metal centers in 8a. UV-Vis studies show a remarkable absorption in the region (λ max ＝300-700 nm) for these complexes.