Novel Bonding Modes between Tetrathiafulvalenes (TTFs) and Transition Metal Centers: π‐Bonding and Covalent TTFSiMe 2 −ML n Coordination to Platinum

Two novel strategies for coordinating TTF to transition metal centers have been developed. The reaction of tetrathiafulvalene (TTF) or 3,4‐dimethyltetrathiafulvalene ( o ‐Me 2 TTF) with [Pt(η 2 ‐C 2 H 4 )(PPh 3 ) 2 ] leads to the π complexes [Pt(η 2 ‐TTF)(PPh 3 ) 2 ] ( 1 ) and [Pt(η 2 ‐ o ‐Me 2 TTF)(PPh 3 ) 2 ] ( 2 ), respectively. An X‐ray crystallographic study performed on 2 confirmed, that TTFs act as a π acidic ligand. NMR studies revealed the existence, in solution, of an equilibrium between free and complexed TTF. Dilithiation of o ‐Me 2 TTF and subsequent silylation with ClSiMe 2 H afforded 3,4‐dimethyl‐3′,4′‐(dimethylsilyl)tetrathiafulvalene ( 3 ), which has been structurally characterized. 3 reacts by oxidative addition across [Pt(η 2 ‐C 2 H 4 )(PPh 3 ) 2 ] to give [Pt{η 2 ‐ o ‐(SiMe 2 ) 2 TTFMe 2 }(PPh 3 ) 2 ] ( 4 ), in which the TTF ligand is covalently ligated to platinum via SiMe 2 bridges. The redox properties of 3 and 4 have been investigated by cyclic voltammetry. Strong cathodic shifts of the two redox processes were observed for 4 , implying the TTF core. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)