The thermolysis of Cp ''' Ta(CO)(4) with white phosphorus (P-4) gives access to [{Cp ''' Ta}(2)(mu,eta(2 : 2 : 2 : 2 : 1 : 1)-P-8)] (A), representing the first complex containing a cyclooctatetraene-like (COT) cyclo-P-8 ligand. While ring sizes of n >6 have remained elusive for cyclo-P-n structural motifs, the choice of the transition metal, co-ligand and reaction conditions allowed the isolation of A. Reactivity investigations reveal its versatile coordination behaviour as well as its redox properties. Oxidation leads to dimerization to afford [{Cp ''' Ta}(4)(mu(4),eta(2 : 2 : 2 : 2 : 2 : 2 : 2 : 2 : 1 : 1 : 1 : 1)-P-16)][TEF](2) (4, TEF=[Al(OC{CF3}(3))(4)](-)). Reduction, however, leads to the fission of one P-P bond in A followed by rapid dimerization to form [K@[2.2.2]cryptand](2)[{Cp ''' Ta}(4)(mu(4),eta(2 : 2 : 2 : 2 : 2 : 2 : 2 : 2 : 1 : 1 : 1 : 1)-P-16)] (5), which features an unprecedented chain-type P-16 ligand. Lastly, A serves as a P-2 synthon, via ring contraction to the triple-decker complex [{Cp ''' Ta}(2)(mu,eta(6 : 6)-P-6)] (B).