Heterodi-, -tri- and -tetrametallic Transition-Metal-Complexes

Abstract

Complexes trans-[Pt(CCMc)2(PBu3)2)] (Mc = Fc = Fe(ƞ5-C5H4)(ƞ5-C5H5) (3), [1,2] Mc = Rc = Ru(ƞ5-C5H4)(ƞ5-C5H5) (4)) were synthesized by treatment of cis-[PtCl2(PBu3)2] with McCCH (Mc = Fc (1), Rc (2)). The synthesis of trans-[Pt(PR3)2(CCFc)(CCRʹ)] (R = Bu: Rʹ = H (7a), Rʹ = PPh2 (7b), Rʹ = Rc (7c); R = Ph: Rʹ = 4-C5H4N (8a), Rʹ = C6H4-4-CN (8b), Rʹ = 2,2ʹ-bipyridin-5-yl (8c), Rʹ = C6H4-4-CCH (8d)) was realized by the reaction of trans-[PtCl(PR3)2(CCFc)] (R = Bu (5), R = Ph (6)) with alkynes HCCRʹ. Treatment of 8a with [RuCl2(cymene)]2 (cymene = η6-1-Me-4-iPr-C6H4) or [Rh(η5-C5Me5)Cl2]2 and of 8c with [Mo(CO)4(2,5-norbornadiene)] or [Mn(CO)5Br] led to heterotrimetallic trans-[Pt(PPh3)2(CCFc)(CCRʹ-{M})] (Rʹ = 4-C5H4N: {M} = Ru(η6-cymene)Cl2 (10a), = Rh(η5-C5Me5)Cl2 (10b); Rʹ = 2,2ʹ-bipyridin-5-yl: {M} = Mo(CO)4 (11a), = Mn(CO)3Br (11b)). When 8b,c were reacted with [{[Ti](µ-σ,π-CCSiMe3)2}Cu(MeCN)][PF6] ([Ti] = Ti(η5-C5H4SiMe3)2) then heterotetrametallic trans-[Pt(PPh3)2(CCFc)(CCRʹ-{M})][PF6] ({M} = [Ti](µ-σ,π-CCSiMe3)2Cu: R’ = 2,2ʹ-bipyridin-5-yl (11c), Rʹ = -C6H4-4-CN (11d) were produced. Compounds 3, 4 and 7c were characterized by single-crystal X-ray diffraction studies establishing the trans arrangement at Pt. The electrochemical behaviour of all compounds was investigated by CV showing reversible redox events for Fc in 3, 7a,c, 8a−d, 10a,b, 11b,c in the range of E°1′ = -120 − -85 mV, while M feature irreversible redox processes between 745 and 1230 mV.