Preparation of U(IV) κ1-amidinate complexes by nitrile metathesis

Treating U(IV) imido compounds, Tp*U-2(N-p-methoxyphenyl) (2-OMe) and Tp*U-2(N-pTol) (2-pTol), with benzonitrile or 4-cyanopyridine results in unusual products of multiple bond metathesis ([2 pi+2 pi]-cycloaddition and [2 pi+2 pi]-cycloreversion). H-1 and B-11 NMR, infrared, and electronic absorption spectroscopic analyses provides evidence of tetravalent uranium compounds, while X-ray crystallography confirmed molecular structures to be Tp*U-2[=N-C(=N-pOMePh)pyr] (3-py), Tp*U-2[=N-C(=N-pOMePh)Ph] (3-Ph), Tp*U-2[=N-C(=N-pTol)pyr] (4-py), Tp*U-2[=N-C(=N-pTol)Ph] (4-Ph), Tp*U-2[=N-C(=N-pOMePh)p-CNPh] (5-OMe), and Tp*U-2[=N-C(=N-pTol)p-CNPh] (5-Tol). Previous examples of actinide imidos treated with nitriles resulted in cyclometallated products; thus, the compounds reported represent divergent chemistry in that an kappa(1)-amidinate ligand is formed through [2 pi+2 pi]-cycloaddition and [2 pi+2 pi]-cycloreversion. (C) 2018 Elsevier Ltd. All rights reserved.