Synthesis and Complexation Properties of the Anions (η⁵-C₅Me₅)Ru(PR₂O)₃^2- as Ligands

Reaction of [(η5-C5Me5)Ru(OMe)]2 (2) with HP(O)(OR)2 gave the novel tripod ligands H2(η5-C5Me5)Ru{PO(OR)2}3 (R = Me, Et, iPr, H21). H2(η5-C5Me5)Ru{PO(Ph2)}3 was formed with HP(O)Ph2. [(η5-C5Me5)RuCl2]2 (3) with NaP(O)(OEt)2 similarly gave Na2(η5-C5Me5)Ru{PO(OEt)2}3 (Na21; Na2L). Either the hydrogen form or the sodium salt was reacted with main group and transition metal halides to yield complexes [ML2]n- (M = SiIV, TiIV, NbIV, n = 0; CoII, n = 2; CrIII, FeIII, n = 1), or complexes of the form LMX with MX = BPh, VO. Reaction of Na2(η5-C5Me5)Ru{PO(Ph2)}3 with TiCl4 gave intermediately [LTiCl2]2 which readily hydrolyzed on chromatography over Al2O3 to trinuclear (LTiO)3(μ3-O)H2. The latter was characterized by X-ray structure analysis. It crystallizes in the cubic space group Pa3 (No. 205), z = 8, a = 30.83(1) Å, V = 29300(30) Å3. From the reaction of Na21 and 3 under appropriate conditions, the mixed valence complex LRu(η5-C5Me5) (4) was isolated. Compounds were characterized by spectroscopy and electrochemistry. From absorption spectra of the CoII and the CrIII complex ligand field parameters Δo = 902 and 1450 cm-1, respectively, were derived, placing 1 near F- in the spectrochemical series.