New bimetallic [(Cl)3Pt(dpop′)M(dpop′)](PF6) (M=Ru(II) and Os(II); dpop′=dipyrido (2,3-a:3′,2′-j)phenazine) complexes using dpop′ as a novel mixed denticity bridging ligand

• Published in: Inorganica Chimica Acta 2013-05, Vol.401, p.95-100
• Main Authors: Ruminski, Ronald R., Canaria, Jeffrey A., Padilla, Roberto
• Format: Article
• Language: English
• Subjects: Bimetallic complexes; Bridging ligands; Osmium(II)complexes; Platinum(II)complexes; Ruthenium(II)complexes
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2013.03.016

Dpop′ is used for the first time as a bridging ligand. Two new complexes, [(Cl)3Pt(dpop′)Os(dpop′)](PF6) and [(Cl)3Pt(dpop′)Ru(dpop′)](PF6) with tridentate coordination to Os(II) or Ru(II) and monodentate coordination to Pt(II) have been synthesized and their electronic absorption, electrochemical and NMR properties studied. [Display omitted] •New complexes [(Cl)3Pt(dpop′)M(dpop′)](PF6) (M=Ru(II) and Os(II)) are reported.•These are the first complexes using dpop′ as a bridging ligand (BL).•Intense MLCT transitions are at longer wavelength versus the monometallic complexes.•Reversible dpop′ (BL) reductions shift +0.20V due to platination.•NMR resonances for dpop′ (BL) are shifted downfield from dpop′(TL). The dpop′ (dipyrido (2,3-a:3′,2′-j)phenazine) ligand structurally displays the possibility of a mixed denticity bridging ligand (BL) with low lying π∗ orbitals. Previously prepared complexes with Fe(II); Ru(II); Os(II) and Re(I) have only demonstrated tridentate coordination to dpop′ and it’s use as a terminal ligand (TL). In this study two new bimetallic complexes [(Cl)3Pt(dpop′)M(dpop′)](PF6) (M=Ru(II) and Os(II)) were synthesized and are the first to use dpop′ as a bridging ligand (BL), with monodentate coordination to Pt(II) and tridentate coordination to Ru(II) and Os(II). The electronic absorption spectra display Ru(II) and Os(II) (dπ)→dpop′ (π∗) (BL) MLCT transitions shifted to lower energy due to stabilization of the bridging dpop′ (π∗) acceptor orbitals. Cyclic voltammetry shows the reversible Ru+2/+3 and Os+2/+3 redox couples are at the same potentials as the respective [M(dpop′)2](PF6)2 complexes while the bridging dpop′0/−1 reversible reductions are shifted to less negative potential by 0.2V. NMR data show downfield shifts for protons bound to the dpop′ (BL) versus dpop′ (TL) ligands.