Reactivity of bulky Ln(ii) amidinates towards P4, As4, and As4S4

Abstract

The reduction of P₄, As₄ and As₄S₄ (realgar) with the sterically encumbered reductants [(DippForm)₂Ln(thf)₂] (Ln = Sm, Yb; DippForm = {(2,6-ⁱPr₂C₆H₃)NC(H) = N(2,6-ⁱPr₂C₆H₃)}⁻) is reported. For the first time, purely f-element containing inverse inorganic sandwich complexes [{(DippForm)₂Sm}₂(μ²-η⁴:η⁴-E₄)] (E = P, As), featuring a π-aromatic cyclo [E₄]²⁻ middle deck, were obtained upon reaction with P₄ and As₄. The reaction with realgar leads to a cage disruption and the formation of the unusual species [{(DippForm)(DippForm-AsS₂)}Ln(thf)]. The reactivity of divalent Ln amidinates towards main group molecules is in comparison to metallocenes faster, more efficient and thus significantly influenced by the ligand environment. Experimental results are supported by DFT calculations.