Gyroscope-Like Platinum and Palladium Complexes with Trans-Spanning Bis(pyridine) Ligands Academic Article uri icon

abstract

  • Pyridines with one or two substituents terminating in vinyl groups are prepared. Intramolecular ring-closing metatheses of trans-MCl 2 adducts and hydrogenations supply the title compounds. Williamson ether syntheses using the alcohols HO(CH 2) nCH=CH 2 (n = 1 (a), 2 (b), 3 (c), 4 (d), 5 (e), 6 (f), 8 (h), 9 (i)) and appropriate halides give the pyridines 2-NC 5H 4(CH 2O(CH 2) nCH=CH 2) (1a,b), 3-NC 5H 4(CH 2O(CH 2) nCH=CH 2) (2a-e,h,i), and 2,6-NC 5H 3(CH 2O(CH 2) nCH=CH 2) 2 (4a-d) in 92-45% yields. Reactions of 3,5-NC 5H 3(COCl) 2 and HO(CH 2) nCH=CH 2 afford the diesters 3,5-NC 5H 3(COO(CH 2) nCH=CH 2) 2 (5a-f,h, 90-41%). The reaction of 3,5-NC 5H 3(4-C 6H 4OH) 2, Br(CH 2) 5CH=CH 2, and Cs 2CO 3 yields 3,5-NC 5H 3(4-C 6H 4O(CH 2) 5CH=CH 2) 2 (8; 32%). Reactions of PtCl 2 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 H 2 (Pd/C) to give trans-PtCl 2[2,2′-(NC 5H 4(CH 2O(CH 2) 2n+2OCH 2)H 4C 5N)] (trans-11a,b; 79-63%), trans-PtCl 2[3,3′-(NC 5H 4(CH 2O(CH 2) 2n+2OCH 2)H 4C 5N)] (trans-13,d,h,i; 93-80%), trans-PtCl 2[2,6,2′, 6′-(NC 5H 3(CH 2O(CH 2) 2n+2OCH 2) 2H 3C 5N)] (trans-18a,b; 22-10%), trans-PtCl 2[3,5,3′,5′-(NC 5H 3(COO(CH 2) 2n+2OCO) 2H 3C 5N)] (trans-20d-f,h; 45-14%), and trans-PtCl 2[3,5,3′,5′-(NC 5H 3(4-C 6H 4O(CH 2) 12O-4- C 6H 4) 2H 3C 5N)] (40%). A previously reported ring-closing metathesis of trans-PdCl 2[2,6- NC 5H 3(CH 2CH 2CH=CH 2) 2] 2 is confirmed, and the new hydrogenation product trans-PdCl 2[2,6,2′,6′-(NC 5H 3((CH 2) 6) 2H 3C 5N)] (trans-16; 62%) is isolated. Additions of CH 3MgBr to 12b,h and 13d,h afford the corresponding PtClCH 3 species (94-41%), but analogous reactions fail with 2-substituted pyridine adducts. The reaction of trans-19c with PhC≡CH and CuI/i-Pr 2NH gives the corresponding PtCl(C≡CPh) adduct (18%). The crystal structures of trans-17a, trans-11b, trans-13d, trans-13ḣCH 2Cl 2, trans-16, trans-18a,b, and trans-20ė2CHCl 3 are determined. Steric effects in the preceding data, especially involving 2-substituents and the MCl 2 or MCl(X) rotators, are analyzed in detail. © 2012 American Chemical Society.

altmetric score

  • 0.25

author list (cited authors)

  • Zeits, P. D., Rachiero, G. P., Hampel, F., Reibenspies, J. H., & Gladysz, J. A.

citation count

  • 40

publication date

  • March 2012