Dinuclear Tin(II) Complex of a Bulky cis ‐Oxamide: Synthesis, Characterization, Crystal Structure, and DFT Studies

The reaction of the di‐lithiated oxamide of 1 with two equivalents of SnCl 2 provided the tin trans ‐oxamide 3 . In solution, spectroscopic analysis suggests exclusively the formation of a trans ‐oxamide ( trans ‐ 3 ). However, the solid state shows an atypical cis ‐oxamide ( cis ‐ 3 ), where the oxamide fragment acts as an anti‐Janus head ligand. An 119 Sn‐NMR variable temperature experiment ([D 8 ]THF) of the trans ‐oxamide ( trans ‐ 3 ) was performed however, at lower temperature no additional signal was observed, which confirmed the absence of a dynamic equilibrium. Dispersion‐corrected density functional calculations revealed that the cis conformation of this tin(II) oxamide complex is more stable than the trans isomer by 1.4 kcal · mol –1 .