Antiferromagnetic complexes involving metal—metal bonds

Summary The photochemical reaction of the antiferromagnetic binuclear complex (CpCrSCMe3)2S (I, Cp=cyclopentadienyl) with Mn2(CO)10 in THF yields the adduct (CpCrSCMe3)2S·Mn2(CO)9 (IV). According to X-ray diffraction data, the fragments in IV are linked through an Mn−S bond (2.448(2) A), and the geometry of I changes only insignificantly upon the addition of Mn2(CO)9: the Cr−Cr bond distance changes from 2.689(8) A in I to 2.740(8) A in IV, the Cr−S(sulphide) bond length increases from 2.24(1) A (I) to 2.31(1) A (IV), whereas the Cr−S (thiolate) bond and CrSCr angles (72.7(3) and 71.4(3)°) remain almost unaffected. Accordingly, formation of the adduct has little affect on the magnetic properties of I (the exchange parameter, −2J, value is equal to 440 cm−1 for IV and 430 cm−1 for I). Compound I reacts with Co2(CO)8 in THF at 20°C without UV irradiation to give the trinuclear cluster, (Cp2Cr2SCMe3)-(μ3-S)2Co(CO)2 (V). Compound V is antiferromagnetic (−2J 530 cm−1, the Co atom is diamagnetic) and, according to the X-ray structural data, contains the CrCrCo metallacycle (the bond lengths are: Cr−Cr, 2.617(1); Cr−Co, 2.579(1) and 2.592(1) A) and sulphide bridges above and below the metallacycle plane. The effect of the coordination number of M on the transformations of the adducts of the type (CpCrSCMe3)2S·M2(CO)n is discussed.