The reaction of (CH 3C 5H 4CrSCMe 3) 2S (Ia) with Cp 2Mn in boiling toluene (containing some THF) has been used to prepare a pentanuclear cluster, [(CH 3C 5H 4) 2Cr 2(SCMe 3)(μ 3-S) 2]Mn (II), which is antiferromagnetic and crystallizes into the monoclinic crystal system: space group Cc, a 26.540(10), b 9.208(3), c 21.595(9) Å; β 135.30(2)°, V = 3712.1 Å 3, Z = 4. According to X-ray analysis, cluster II contains a metallospirane core, Cr 4Mn, which appears to be strongly distorted, compared to its earlier studied cyclopentadienyl analogue [Cp 2Cr 2SCMe 3(μ 3-S) 2] 2Mn, due to the short intramolecular contacts CH 3…S (2.9–3.1 Å). The angle between the metal triangle planes of Cr 2Mn is 109.60°. Here, the two long CrMn bonds (3.019(3) and 3.104(4) Å) are combined with the shorter Cr Cr bond (2.651(6) Å) in one triangle and, vice versa, the less extended CrMn bonds (2.839(4) and 2.967(3) Å) are combined with a longer CrCr bond (2.726(6) Å) in the other triangle of Cr 2Mn. By the reaction of Ia with [CpFe(CO) 2] 2 (taken in the ratio of 2 1 ) in boiling toluene, the antiferromagnetic cluster [(CH 3C 5H 4) 2Cr 2(SCMe 3)(μ 3-S) 2] 2Fe (III) has been synthesized in which the same distortions as in cluster II are present, as revealed by X-ray analysis. In the metallospirane core of the molecule of III, the Cr 2Fe triangles make an angle of 113.84° with each other. In this cluster, the CrCr distances in the peripheral binuclear fragments (CH 3C 5H 4) 2Cr 2(μ-SCMe 3)(μ 3-S) 2 are practically equal (2.688(3) and 2.661(3) Å), whereas the FeCr bond lengths are markedly different (2.749(2) and 2.827(2) Å in on triangle and 2.910(2) and 2.969(2) Å in the other). The dependence of the geometries of clusters II and III on the steric effects of the methyl substituents in the cyclopentadienyl ligands and on the electronic effect of the central metal atom (Mn II or Fe II) is discussed.