Novel isonitrile derivatives of a diruthenium carbonyl complex, (μ2.η3:η5-guaiazulene)Ru2(CO)5 (2), were synthesized by substitution of a CO ligand by an isonitrile, and were subjected to studies on thermal and photochemical haptotropic interconvension. Treatment of 2 (a 45:55 mixture of two haptotropic isomers. 2-A and 2-B) with RNC at room temperature resulted in coordination of RNC and alternation of the coordination mode of the guaiazulene ligand to form (μ2η1:η5-guaiazulene)Ru2(CO)5(CNR), 5d-5f, [5d; R = 'Bu, 5e; 2,4,6-Me3C6H2, or 5f; 2,6-iPr2C6H3] in moderate to good yields. Thermal dissociation of a CO ligand from 5 at 60 °C resulted in quantitative formation of a desirable isonitrile analogue of 2. (μ2.η3:η5-guaiazulene)Ru2(CO)4(CNR), 4d-4f, [4d; R = 'Bu, 4e; 2,4,6-Me3C6H2, or 4f' 2,6-iPr2H3], as a 1:1 mixture of the two haptotropic isomers. A direct synthetic route from 2 to 4d-4f was alternatively discovered; treatment of 2 with one equivalent of RNC at 60 °C have 4d-4f in moderate yields. All of the new compounds were characterized by spectroscopy, and structures of 5d (R = 'Bu) and 4d-A (R = 'Bu) were determined by crystallography. Thermal and photochemical interconvention between the two haptotropic isomers of 4d-4f revealed that the isomer ratios in the thermal equilibrium and in the photostatic state were in the range of 48:52-54:46.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry
- Materials Chemistry