Boron-Metallated Borirenes and Bis(Borirenes).

Heating the metalloborylene complex [{(η(5) -C5 Me5 )Fe(CO)2 }(μ-B){Cr(CO)5 }] with alkynes and diynes leads to the formation of B-metallated borirenes and a bis(B-metallated borirene) through formal transfer of the metalloborylene moiety [(η(5) -C5 Me5 )(OC)2 Fe(B:)]. By using this protocol, a range of B-metallated borirenes with electron-donating and electron-withdrawing substituents are prepared, and these are studied spectroscopically, structurally, and computationally. The yellow-orange color of the complexes is additionally explained through time-dependent density functional theory calculations.