Antiferromagnetic complexes with metal-metal bonds XXVI. Synthesis, molecular structure and magnetic properties of mixed-metal triangular clusters, Cp2Cr2(μ-SR)(μ3-S)2FeCp (R = CMe3 or Ph) and linear mixed-metal chain CpCr(μ-SPh)3Fe(μ-SPh)3CrCp

Abstract The antiferromagnetic triangular cluster Cp 2 Cr 2 (μ-SCMe 3 )(μ 3 -S) 2 FeCp ( II ) ( - 2 J = 520 cm −1 ) with a strongly bonded Cr 2 Fe metal core (CrCr 2.650(3), CrFe 2.666(3) and 2.675(2) A) was obtained by prolonged photochemical reaction of Cp 2 Cr 2 (μ-SCMe 3 ) 2 (μ-S) ( I ) and Cp 2 Fe 2 (CO) 4 in THF. It was shown that thermal reaction between complex I and Cp 2 Fe 2 (CO) 2 (μ-SPh) 2 yields two clusters, diamagnetic triangular Cp 2 Cr 2 (μ-SPh)(μ 3 -S) 2 FeCp ( III ) and antiferromagnetic metal chain CpCr(μ-SPh) 3 Fe(μ-SPh) 3 CrCp ( IV ) (μ eff . 5.29 (296 K) - 3.95 (77 K) μ B ). Complex III as well as II involves the strongly bonded metal core Cr 2 Fe (CrCr 2.637(3), CrFe 2.644(3) and 2.672(3) A), whereas the FeCr bonds in the linear chain of IV are considerably elongated (up to 2.996(3) and 2.969(3) A), which is in agreement with their reduced bond order (equal to 1/2).