Cobalt may be substituted by its heavier congener rhodium to give rhodocene, an even stronger reducing agent.
kˈoʊbɔlt mˈeɪ biː sˈʌbstɪtˌuːɾᵻd baɪ ɪts hˈɛviɚ kəndʒˈɛnɚ ɹˈoʊdiəm tə ɡˈɪv ɹˈoʊdəsˌiːn, ɐn ˈiːvən stɹˈɔŋɡɚ ɹᵻdˈuːsɪŋ ˈeɪdʒənt.