Cobalt a structural analog to ferrocene, with cobalt in place of iron. Cobaltocene is much more sensitive to oxidation than ferrocene. Cobalt carbonyl (Co(CO)) is a catalyst in carbonylation and hydrosilylation reactions. Vitamin B (see below) is an organometallic compound found in nature and is the only vitamin that contains a metal atom. An example of an alkylcobalt complex in the otherwise uncommon +4 oxidation state of cobalt is the homoleptic complex (Co(1-norb)), a transition metal-alkyl complex that is notable for its stability to β-hydrogen elimination. The cobalt(III) and cobalt(V) complexes [Li(THF)][Co(1-norb)] and [Co(1-norb)][BF] are also known. Co is the only
Chemical element isotopes: specifically the elements without any stable isotopes are technetium (atomic number 43), promethium (atomic number 61), and all observed elements with atomic numbers greater than 82. Of the 80 elements with at least one stable isotope, 26 have only one single stable isotope. The mean number of stable isotopes for the 80 stable elements is 3.1 stable isotopes per element. The largest number of stable isotopes that occur for a single element is 10 (for tin, element 50). The mass number of an element, "A", is the number of nucleons (protons and neutrons) in the atomic nucleus. Different isotopes