Select all statements concerning metallocenes that are true (you may select more than one answer) Select one or more: a. Ferrocene is paramagnetic b. Metallocene complexes always have 18 valence electrons c. Nickelocene is paramagnetic d. Nickelocene has 20 valence electrons e. Metallocenes are never stable in air f. Metallocenes typically contain cyclopentadienyl (C5H5− )ions bound to a transition metal centre g. Titanocene is highly unstable due to a low valence electron count. h. Cobaltocene is more stable than ferrocene as a result of a higher valence electron count.