Charge-transfer salts of ferrocene derivatives with bis(maleonitriledithiolato)metallate(III) complexes ([M(mnt)(2)](-), M = Ni, Pt): A ground-state high-spin [(Ni(mnt)(2))(2)](2-) dimer

New hexamethylated ferrocene derivatives containing thioether moieties (1,1 '-bis[(tert-butyl)thio]2,2',3,3',4,4'-hexamethylferrocene (3a,b)) or fused S-heteropolycyclic substituents (rac-1-[(1,3-benzodithiol-2-yliden)methyl]- 2,2',3,3',4,4'-hexamethylferrocene (14)), as well as a series of ferrocene- substituted vinylogous tetrathiafulvalenes (1,1'-bis[1,1'-bis[1,2-bis(1,3-d ithiolo[4,5-b][1,4]dithiin-2-yliden)ethyl]ferrocene (6a), 1,1'-bis[1-(1,3-b enzodithiol-2-yliden)-2-(5,6-dihydro-1,3-dithiolo[4,5-b][1,4]dithiin-2-ylid en)ethylferrocene (6b), [1,2-bis(1,3-benzodithiol-2-yliden)-ethyl]ferrocene (21a), [1-(1,3-benzodithiol-2-yliden)-2-(5,6-dihydro-1,3-dithiolo[4,5-b][1 ,4]dithiin-2-yliden)-ethyl]ferrocene (21b), [1,2-bis(5,6-dihydro-1,3-dithio lo[4,5-b][1,4]dithiin-2-yliden)ethyl]ferrocene (21c), [1-(5,6-dihydro-1,3-d ithiolo[4,5-b][1,4-b][1,4]dithiin-2-yliden)-2-(1,3-benzodithiol-2-yliden)et hyl]ferrocene (21d)) were prepared and fully characterized. Their redox pro perties show that some of them are easily oxidized and undergo transformati on to paramagnetic salts containing bis(maleonitriledithiolato)-metallate(I II) anions [M(mnt)(2)](-) (M = Ni, Pt; bis[2,3-dimercapto-kappa S)but-2-ene dinitrilato(2(-))]nickelate (1(-)) or -platinate (1(-)). The derivatives [3 a] [Ni(mnt)(2)] (26), [3a][Pt(mnt)(2)] (27), [Fe{(eta(5)-C5Me4S)(2)S}] [Ni( Mnt)(2)] (28), [Fe{(eta(5)-C5Me4S)(2)S}] [Pt(mnt)(2)] (29), [5] [Ni(mnt)(2) ] . ClCH2CH2Cl (30), [6a] [Ni(mnt)(2)] (31), [6a] [Ni(mnt)(2)] . ClCH2CH2Cl (31a), [6a] [Pt(mnt)(2)] [32), and [6b] [Ni(mnt)(2)] (33) were prepared an d fully characterized, including by SQUID (superconducting quantum interfer ence device) susceptibility measurements. X-Ray crystal-structural studies of the neutral ferrocene derivatives 6a,b, 21c,d, and 1,1'-bis[1-(1,3-benzo dithiol-2-yliden)-2-oxoethyl]ferrocene (23), as well as of the charge-trans fer salts 26-28, 30, and 31a, are reported. The salts 28 and 30 display bot h a D(+)A(-)A(-)D(+) structural motif, however, with a different relative a rrangement of the [P{Ni(mnt)(2)}(2)](2-) dimers, thus giving rise to differ ent but strong antiferromagnetic couplings. Salt 26 exhibits isolated ferro magnetically coupled [(Ni(mnt)(2)}(2)](2) dimers. Salt 27 displays a D(+)A( -)D(+)A(-) structural motif in all three space dimensions, and a week ferro magnetic ordering at low temperature. Salt 31a, on the contrary shows segre gated stacks of cations and anions. The cations are connected with each oth er in two dimensions, and the: anions are separated by a 1,2-dichloroethane molecule.