Exploring Spin-Orbit Effects in a [Cu6Tl]+ Nanocluster Featuring an Uncommon Tl-H Interaction

Reaction of [CuH(PPh3)](6) with 1 equiv. of Tl(OTf) results in formation of [Cu6TlH6(PPh3)(6)][OTf] (<bold>[1]OTf]</bold>), which can be isolated in good yields. Variable-temperature H-1 NMR spectroscopy, in combination with density functional theory (DFT) calculations, confirms the presence of a rare Tl-H orbital interaction. According to DFT, the H-1 chemical shift of the Tl-adjacent hydride ligands of <bold>[1]</bold>(+) includes 7.7 ppm of deshielding due to spin-orbit effects from the heavy Tl atom. This study provides valuable new insights into a rare class of metal hydrides, given that <bold>[1][OTf]</bold> is only the third isolable species reported to contain a Tl-H interaction.