Molecular and Crystal Structures of Some Bromocymantrenes

Crystals of mono- and dibromo as well as two isomeric tribromocymantrenes [Mn(C₅H_5-nBr_n)(CO)₂(PPh₃)] (n = 1–3) were obtained and examined by X-ray diffraction. The degree of substitution has only minor influence on bond lengths and angles. However, the relative orientations of bromo substituents and PPh₃ ligand as well as relative orientation of the cyclopentadienyl ring and the MnC₂P tripod are sensitive to the number and position of bromines. All compounds show weak Br…O interactions, mostly combined with hydrogen bonds, while Br…Br interactions are unimportant. These interactions lead to sometimes complicated chain structures.

In the crystal structures of the bromocymantrenes [Mn(C₅H_5-nBr_n)(CO)₂(PPh₃₎] (n = 1–3) a combination of H bonds and Br…O/Br…Br interactions leads to one-dimensional molecular chains or double-chains, which are not further connected in the other dimensions.