 The ( C5H5 ) − ion in samarium cyclopentadienides can be replaced by the indenide ( C9H7 ) − or cyclooctatetraenide ( C8H8 ) 2 − ring , resulting in Sm ( C9H7 ) 3 or KSm ( η8 @-@ C8H8 ) 2 . The latter compound has a similar structure to that of uranocene . There is also a cyclopentadienide of divalent samarium , Sm ( C5H5 ) 2 – a solid that sublimates at about 85 ° C. Contrary to ferrocene , the C5H5 rings in Sm ( C5H5 ) 2 are not parallel but are tilted by 40 ° . 
