Long-Range Through-Bond Heteronuclear Communication in Platinum Complexes

Four analogous platinum stilbene- and stilbazole-based complexes exhibit unusual long-range heteronuclear spin−spin coupling in solution. Single crystal analysis and NMR experiments show that the 19F, 31P, and 195Pt nuclei communicate over large distances (0.9−1.3 nm) through bond rather than through space. Spin−spin couplings between 195Pt and 19F over seven bonds and between 31P and 19F over eight bonds are observed with 7JPtF = 2.9 Hz and 8JPF = 11.8 Hz. Remarkably, a very large spin coupling between 195Pt and 19F over six bonds (6JPtF = 40.1 Hz) is also observed in a structurally related pyridinium complex. Experimental and gNMR (version 5.0) simulated 19F{1H}, 31P{1H}, and 195Pt{1H} spectra of the complexes reveal a three-spin AMY system (A = 31P, M = 31P, Y = 19F) or a five-spin AMY3 flanked by a four-spin AMXY or a six-spin AMXY3 system (X = 195Pt), respectively. Density functional theory calculations at the PBE0/SDD level of theory show a π-conjugated metal−ligand network, which may contribute to the experimentally observed spin−spin interactions.