The first examples of Co(II) mesoionic carbene complexes (CoX2DippMIC2; X = Cl−, Br−, I−) demonstrate a new electronic perturbation on tetrahedral Co(II) complexes. Using absorption spectroscopy and magnetometry, the consequences of the MIC's strong σ-donating/minimal π-accepting nature are analyzed and shown to be further tunable by the nature of the coordinated halide.
