Synthesis and structure of vaulted trans-Bis[1-(2-phenoxy)-imidazol-2-ylidene-C2,O]platinum(II) complex

trans-Bis[1-(2-phenoxy)-imidazol-2-ylidene-C2,O]platinum(II) complex bearing a dodecamethylene bridge (1) was synthesized and characterized by 1H, 13C NMR, COSY, NOESY, FT-IR, high-resolution mass spectroscopy, and single crystal X-ray diffraction. X-ray and 2D-NMR analyses revealed that complex 1 has a characteristic syn-conformation in both the solid and solution states, where cofacial phenoxy-NHC ligands are folded and fixed under strong restriction by the vaulted structure. A crystal of 1 obtained from EtOH exhibits weak blue phosphorescence under UV excitation at 320 nm.