Synthesis and structure of the heterotrinuclear chromium-palladium clusters (RC5H4CrCl)2-(μ3S)(μ-SCMe3)2Pd(PPh3) with ferromagnetic exchange interactions over the CrSCr system

Abstract Reactions of (RC5H4)2Cr2(SCMe3)2S(I, R = H; II, R = Me) with (PPh3)2PdCl2 in benzene at 20°C gives trinuclear complexes (RC5H4)2Cr2Cl2(μ3-S)(μ-SCMe3)2Pd(PPh3)(III, R = H; IV, R = Me). The structure of IV as a monobenzene solvate is established by an X-ray analysis (black-green triclinic crystals space group P 1 with a = 11.403(4), b = 14.933(5), c = 14.131(5) A, α = 99.13(3), β = 112.72(3), γ = 95.65(3)°, V = 2201.6 A, Z = 2; IV·C6H6). The structure was solved by direct methods and refined in an anisotropic approximation to R = 0.046, Rw = 0.058 for 7643 reflections with I ⩾ 2σ(I). In the molecule of IV metal atoms are separated by non-bonding distances (Cr … Cr 4.079(I), Cr … Pd 3.230(I) and 3.380(I) A) but linked by the bridging tridentate sulphur atom (CrS 2.339(2) and 2.329(2), PdS 2.327(2) A), and two SCMe3 groups between Pd and Cr (CrS 2.396(2) and 2.403(2), PdS 2.350(2) and 2.381(2) A, CrŜPd 85.14(6) and 89.92(6)°). The Cl atoms are transferred from Pd to Cr atoms (CrCl 2.308(2) A) and being terminally coordinated are in trans-positions to each other (as well as η-CH3C5H4 rings) with respect to the Cr2Pd plane. Cr atoms in III and IV exhibit ferromagnetic exchange interactions over the CrŜCr system (+2J = 28 and 11 cm−1, respectively).