Conversion between Doubly and Triply Carboxylate Bridged Bis(ethylzinc) Complexes and Formation of the (μ-Oxo)tetrazinc Carboxylate [Zn(4)O(Ar(Tol)CO(2))(6)]

[Image: see text] Ethylzinc 2,6-bis(p-tolyl)benzoate converts between two forms in solution. Through NMR spectroscopic techniques and X-ray crystallography, the species in equilibrium were identified as [Zn(2)(Ar(Tol)CO(2))(2)(Et)(2)(THF)(2)] (1), [Zn(2)(Ar(Tol)CO(2))(3)(Et)(THF)] (2), and diethylzinc (Ar(Tol) = 2,6-bis(p-tolyl)phenyl). The equilibrium provides a model for understanding the speciation between doubly and triply m-terphenylcarboxylate bridged diiron(II) and mononuclear iron(II) complexes. Evidence is presented for the occurrence of coordinatively unsaturated trigonal zinc species in solution. Both 1 and 2 decompose in air to form the T-symmetric oxozinc carboxylate [Zn(4)O(Ar(Tol)CO(2))(6)] (3).