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

Complexes trans-[Pt(C[tbnd]CMc)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 McC[tbnd]CH (Mc = Fc (1), Rc (2)). The synthesis of trans-[Pt(PR₃)₂(C[tbnd]CFc)(C[tbnd]CRʹ)] (R = Bu: Rʹ = H (7a), Rʹ = PPh₂ (7b), Rʹ = Rc (7c); R = Ph: Rʹ = 4-C₅H₄N (8a), Rʹ = C₆H₄-4-C[tbnd]N (8b), Rʹ = 2,2ʹ-bipyridin-5-yl (8c), Rʹ = C₆H₄-4-C[tbnd]CH (8d)) was realized by the reaction of trans-[PtCl(PR₃)₂(C[tbnd]CFc)] (R = Bu (5), R = Ph (6)) with alkynes HC[tbnd]CRʹ. 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(C[tbnd]CFc)(C[tbnd]CRʹ-{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-C[tbnd]CSiMe₃)₂}Cu(MeC[tbnd]N)][PF₆] ([Ti] = Ti(η⁵-C₅H₄SiMe₃)₂) then heterotetrametallic trans-[Pt(PPh₃)₂(C[tbnd]CFc)(C[tbnd]CRʹ-{M})][PF₆] ({M} = [Ti](µ-σ,π-C[tbnd]CSiMe₃)₂Cu: R’ = 2,2ʹ-bipyridin-5-yl (11c), Rʹ = -C₆H₄-4-C[tbnd]N (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.