Polynuclear iron/tantalum and tantalum complexes with As-n ligands

Starting with [Cp " Ta(CO)(4)] (1) (Cp " = (C5H3Bu2)-Bu-t-1,3) and As-4 or ((BuAs)-Bu-t)(4) (2) its thermolysis at 190 degrees C in decalin gives [{Cp " Ta}(2)(mu-eta(4):eta(4)-As-8)] (3), which is also formed according to eq uation(2) in addition to [{Cp " Ta}(3)As-6] (5). The reaction of 1 or [{Cp* (OC)(2)Fe}(2)] (6) with 3 affords 5 or [{Cp*Fe}{Cp " Ta}As-5] (8) demonstra ting the use of 3 as As-n source. 8 can also be synthesized from 1 and [Cp* Fe(eta(5)-As-5)] (7) for which the cothermolysis of 2 and 6 gives a better yield.