1,2-Maleonitrile 1,2-dithiolate ligands

Like metal chelates of some other dithio ligands, e.g. maleonitrile dithiolate, dithio-/J-diketonato complexes undergo reversible redox reactions in non-aqueous solvents. The square-planar complexes [ML2] (M = Co, Ni, Pd and Pt) exhibit two consecutive one-electron reductions as shown in equation (5).252,253... 

Three 1 1 Fe Cu model compounds have been reported, each of which contains a dmuclear anion in which an iron(III) porphyrin and a copper(II) maleonitrile dithiolate are bridged by one of the thiolate anions. The other ligand to Fe in each case is THF. The cations of the three compounds are either [TPPFe(THF)2]+, [TPPGa(THF)2]+, or [TPPA1(THF)(H20)]+ (Figure 8(e)). The structural results and the Mossbauer parameters suggest that the Fe center in... 

By performing the CV experiments, only three reversible waves are found, with half-wave potentials as detailed in Table 7.9. The fourth expected reduction eventually leading to [la]3- has not been observed, although it has been recorded for a related complex with the maleonitrile-l,2-dithiolate ligand, at —1.83 V. The [la]3-complex should contain the MNO 8 moiety. As discussed in Section 7.5, iron complexes of this configuration are scarce, and very elusive to a proper characterization. 

The structures of typical ligands were shown earlier in Figure 1.9 and will also be shown later in Figures 3.1 and 3.2. Complexes include some metal halides, hydrates, amines, amides and imides, such as Ti(NR2)4 (R is an alkyl group), oxides, H3B NR3 (a borane-amine adduct), Co(MNT)2 (MNT = maleonitrile dithiolate), Cupc (pc = phthalocyanine), Mo(CO)6, cluster carbonyls, and metal acetylacetonate derivatives. 

For platinum(II), Balch and coworkers [78] have studied the reaction of a biscar-bene platinum(II) dicyanide complex with thallium(I) in basic solution (Scheme 18). They obtained two polymorphs involving Pt -Xl contacts a yellow dimeric structure and a red extended structure. Subsequent work by the same authors [79] showed that replacement of the CN ligands with dimethylglyoxime or maleonitrile dithiolate provides access to a range of extended structures based on Pt i Xl interactions. 

Transition metal complexes (1) of 1,2-dicyanoethylene-1,2-dithiol (maleonitrile), mnt, have received special study since this ligand can stabilize transition metals in a variety of oxidation states and the high electron affinity of the terminal cyanide groups aids the delocalization of charge within the complex, thus reducing potential coulombic repulsions. 

When considering the synthesis of a dithiolene complex, it is essential to bear in mind that dithiolenes vary widely in their electronic properties. If one simply seeks an unsaturated chelating dithiolate, the most convenient options are benzenedithiolate and the inorganic dithiolenes 1,3-dithiole-2-thione-4,5-dithiolate (dmit2 ) and l,2-maleonitrile-l,2-dithiolate (l,2-dicyanoethene-l,2-dithio-late) (mnt2 ). Large-scale syntheses of these ligands are available. Dithiolenes... 

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