In situ syntheses of trans-spanned octahedral ruthenium complexes. Crystal structures of trans-[Ru(Cl)(trpy){Ph2PC6H4CH2O(CO)(CH2)4(CO)OCH2C6H4PPh2}][PF6]·0.25C6H5Me·0.5CH2Cl2 and trans-[Ru(Cl)(trpy)(PPh3)2][BF4]·CH2Cl2†

Abstract

The formation of stable, undistorted octahedral transition metal complexes which contain a trans-spanning bidentate ligand remains a synthetic challenge. The reported complexes are of the type trans-[Ru(Cl)(trpy){Ph₂PC₆H₄CH₂O(CO)Y(CO)OCH₂C₆H₄PPh₂}][PF₆] [where trpy = 2,2′∶6′,2″-terpyridine and Y = (CH₂)₃ = C3SPAN, 6; (CH₂)₄ = C4SPAN, 7; or isophthalate = ISPAN, 8] and represent the first examples of trans-spanned transition metal complexes which display little bond angle distortion from octahedral geometry and also contain a bridging linkage which is stable towards oxidation, reduction and hydrolysis. These complexes were characterized by elemental analyses, cyclic voltammetry, conductivity and UV-VIS spectroscopy. COSY, HETCOR and variable temperature (¹H and ¹³C) NMR spectra of the complexes are consistent with a flexible spanning linkage that does not demonstrate restricted rotation about either the P–C_ipso or the Ru–P bonds while the X-ray crystal structure analysis of 7 showed that the spanning linkage is positioned to one side of the meridional chloride.