The reaction of KCp
ni (Cp
ni = (C
3H
7)
nC
5H
5-n;
n = 3, 4) with MnCl
2 in THF produces themetallocenes (Cp
3i)
2Mn or (Cp
4i)
2Mn in good yield. Solid-state magnetic susceptibilitymeasurements indicate that orange-red (Cp
3i)
2Mn is in high-spin/low-spin equilibrium atroom temperature. In the solid-state, it has a centrosymmetric sandwich structure with anaverage Mn-C bond
length (2.130(6) Å) typical of low-spin manganocenes. (Cp
3i)
2Mn reducestetracyanoethylene (TCNE) to generate the TCNE radical anion. Despite the presence ofadditional electron-donating isopropyl groups, pale yellow (Cp
4i)
2Mn is entirely high-spinfrom room temperature to 10 K. The crystal structure of (Cp
4i)
2Mn reveals a bent metallocenestructure, with a centroid-Mn-centroid angle of 167.4
![](/images/entities/deg.gif)
and an average Mn-C distance of2.42(2) Å. This structure is consistent with its high-spin electron configuration; the longerMn-C bonds provide relief from the steric strain that would be present in a low-spin complex.The reaction of (Cp
4i)
2Mn with TCNE produces a tricyanovinylation product, C
5(
i-Pr)
4HC(CN)=C(CN)
2, which was characterized by X-ray diffraction.