Gyroscope-Like Platinum and Palladium Complexes with Trans-Spanning Bis(pyridine) Ligands

Abstract

Pyridines with one or two substituents terminating in vinyl groups are prepared. Intramolecular ring-closing metatheses of trans-MCl2 adducts and hydrogenations supply the title compounds. Williamson ether syntheses using the alcohols HO(CH2)nCH═CH2 (n = 1 (a), 2 (b), 3 (c), 4 (d), 5 (e), 6 (f), 8 (h), 9 (i)) and appropriate halides give the pyridines 2-NC5H4(CH2O(CH2)nCH═CH2) (1a,b), 3-NC5H4(CH2O(CH2)nCH═CH2) (2a–e,h,i), and 2,6-NC5H3(CH2O(CH2)nCH═CH2)2 (4a–d) in 92–45% yields. Reactions of 3,5-NC5H3(COCl)2 and HO(CH2)nCH═CH2 afford the diesters 3,5-NC5H3(COO(CH2)nCH═CH2)2 (5a–f,h, 90–41%). The reaction of 3,5-NC5H3(4-C6H4OH)2, Br(CH2)5CH═CH2, and Cs2CO3 yields 3,5-NC5H3(4-C6H4O(CH2)5CH═CH2)2 (8; 32%). Reactions of PtCl2 with 1a,b, 2a–e,h,i, 4a,b (but not 4c,d), 5a,c–f,h, and 8 afford the corresponding bis(pyridine) complexes trans-10a,b (40–12%), trans-12a–e,h,i (84–46%), trans-17a,b (88–22%), trans-19a,c–f,h (94–63%), and trans-22 (96%). Selected adducts are treated with Grubbs’ catalyst and then H2 (P...