Charge transfer dithiolene-donor complexes

There are numerous examples of donor-acceptor complexes involving components like those in Charts 1 and 2 and dithiolene complexes. While there is considerable structural diversity, n-stacking is a common feature. Another common property is partial charge transfer from donor to acceptor, and anions such as (TCNQ) occur. As intimated in the previous example small variations in structure can have large effects on physical properties. 

It should be pointed out that the treatment of phosphorus or sulfur donors bearing ferrocenyl groups with diiodine results in the formation of molecular charge-transfer adducts without simultaneous oxidation of the ferrocenyl groups (Durfey et al. 2000, Gridunova et al. 1982). At the same time, the reaction of 4-ferrocenyl-l,3-dithiolene-2-thione with diiodine leads to a charge-transfer complex in which the iron has been oxidized from Fe" to Fe ". This was confirmed by magnetic measurements and Moessbauer spectroscopy (Allen et al. 2003). 

A particular subgroup of these low-dimensional conductors are the charge transfer complexes between dithiolenes and organic donor species such as TTF and related compounds. Here, nonintegral charge transfer is often seen as the reason for high conductivity down to low temperatures. 

The precursor dithiocarbonates were also used to prepare mesomorphic derivatives of TTF (tetrathiafulvalene), a strong electron donor compound used in the formation of highly conductive charge transfer complexes. Attempts to prepare CT complexes between the mesomorphic dithiolenes as acceptors and these mesomorphic TTF donors showed that the electron acceptor strength of this type of dithiolene does not suffice to form strong donor-acceptor complexes mixtures of the two components form mixed crystals without any visible degree of charge transfer.208... 

Metal dithiolene complexes such as [M(mnt)2] and [M(dmit)2] (see Chart 3) are electron-transfer active and can be readily generated in oxidized or reduced forms with variable charge z and can be used as either donors or acceptors. 

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