Polarised Covalent Thorium(IV)- and Uranium(IV)-Silicon Bonds

We report the synthesis and characterisation of isostructural thorium(IV)- and uranium(IV)- silanide complexes, providing the first structurally authenticated Th-Si bond and a rare example of a molecular U-Si bond. These complexes therefore present the first opportunity to directly compare the chemical bonding of Th-Si and U-Si bonds. Quantum chemical calculations show significant and surprisingly similar 7s, 6d, and 5f orbital contributions from both actinide (An) elements in polarised covalent An-Si bonds