Syntheses and characterizations of multinuclear, chain and layer silver(I) complexes assembled from bispyridine analogues of pyridinyl-hexahydropyrimidine

Abstract

Coordination chemistry of pyridinyl-hexahydropyrimidine has not been studied to date, despite that the organic chemistry and coordination chemistry involving rigid bispyridine (bipy), pyrimidine and their derivatives have been widely reported. In this paper, the one-pot reaction of AgX (X = NO3− and ClO4−) with three rigid-flexible bispyridine analogues, 2-(pyridin-n-yl)hexahydropyrimidine [n =4 (L1), 3 (L2), 2 (L3)], lead to the formation of seven complexes, namely, [AgL1(NO3)]n·n(H2O) (1), [AgL1(NO3)]n (2), [Ag6(L1)4(NO3)6]·6(H2O) (3), [AgL1(CH3CN)]n·n(ClO4) (4), [Ag2(L2)2(NO3)(H2O)]n·n(NO3)·n(H2O) (5), [Ag3(L2)3(CH3CN)2]n0.3n(ClO4) (6), and [Ag2(L3)2(NO3)2] (7), which have been characterized by elemental analysis, IR, TG, PL, powder and single-crystal X-ray diffraction. Structural analyses indicate that the conformational transformations of L1-L3 cause diverse structures. In 1 and 2, L1 presents modes I and II which connects adjacent Ag(I) into fes layers. In contrast, modes III and I in 3 and 4 join adjacent Ag(I) into hexanuclear and ladder chain structures. Complexes 5 and 6 show the same ladder chain structures with the L2 displaying the same coordination mode IV. L3 in 7 exhibits tripodal mode V to connect adjacent two Ag(I), thus forming dinuclear unit. Interestingly, adjacent dinuclear units are further joined by intermolecular hydrogen bonds to form kgd layer. Luminescent investigation reveals that 4 and 6 exhibit emissions from 443 to 581nm.