Transformation of Mononuclear Plutonium(III) Tetrazolate Complexes into Dinuclear Complexes in the Solid State

The salt metathesis reaction of Na­(pmtz)·H2O [pmtz– = 5-(pyrimidyl)­tetrazolate] and PuBr3·nH2O in an aqueous media leads to the formation of the mononuclear compound [Pu­(pmtz)3(H2O)3]·(3 + n) H2O (Pu1, n = ∼8) that is isotypic with the lanthanide compounds [Ln­(pmtz)3(H2O)3]·(3 + n) H2O (Ln = Ce–Nd). Dissolution and recrystallization of Pu1 in water yields the dinuclear compound {[Pu­(pmtz)2(H2O)3]2(μ-pmtz)}2(pmtz)2·14H2O (Pu2), which is isotypic with the lanthanide compounds {[Ln­(pmtz)2(H2O)3]2(μ-pmtz)}2(pmtz)2·14H2O (Ln = Nd and Sm). Like their nine-coordinate ionic radii, the M–O and M–N bond lengths in Pu1/Pu2 and Nd1/Nd2, respectively, are within error of one another. The Laporte-forbidden 4f → 4f and 5f → 5f transitions are also assigned in the UV–vis–NIR spectra for these f-element tetrazolate coordination compounds.