Synthesis and thermal average gas phase molecular structures of bis(pentamethylcyclopentadienyl)-strontium and -barium; the first organo-strontium and -barium structures

The thermal average gas phase molecular structures of bis(pentamethylcyclopentadienyl)-strontium, Sr(C5Me5)2, and -barium, Ba(C5Me5)2, are best described as bent sandwich structures where the mean Sr–C and Ba–C bond distances are 275.0(8) and 289.8(17)pm and the ring centroid–metal–ring centroid angles are 149(3)° and 148(6)° respectively.