Interaction of Copper(II) with Ditopic Pyridyl-β-diketone Ligands: Dimeric, Framework, and Metallogel Structures

Abstract

The interaction of Cu(II) with three β-diketone ligands of type R 1 C(O)CH 2 C(O)R 2 (where R 1 = 2-, 3-, or 4-pyridyl and R 2 = C 6 H 5 , respectively), HL 1 -HL 3 , along with the X-ray structures and the pK a values of each ligand, are reported. HL 1 yields a dimeric complex of type [Cu(L 1 ) 2 ] 2 . In this structure, two deprotonated HL 1 ligands coordinate in a trans planar fashion around each Cu(II) center, one oxygen from each CuL 2 unit bridges to an axial site of the second complex unit such that both Cu(II) centers attain equivalent five-coordinate square pyramidal geometries. The two-substituted pyridyl groups in this complex do not coordinate, perhaps reflecting steric factors associated with the closeness of the pyridyl nitrogen to the attached (conjugated) β-diketonato backbone of each ligand. The remaining two Cu(II) species, derived from HL 2 and HL 3 , are both coordination polymers of type [Cu(L) 2 ] n in which the terminal pyridine group of each ligand is intermolecularly linked to an adjacent copper center to generate the respective infinite structures. HL 2 was also demonstrated to form a fibrous metallogel when reacted with CuCl 2 in an acetonitrile/water mixture under defined conditions.

Dipyridyl β-diketonate complexes and their use as metalloligands in the formation of mixed-metal coordination networks

“…In particular, the Domasevitch 12 and Maverick 13 groups have prepared MMOFs based on 3-(4pyridyl)acetylacetonate, whereas monometallic networks have also been prepared with pyridyl-substituted !-diketonates. 14,15 We recently communicated the use of the 1,3-di(4-pyridyl)propane-1,3-dionato ligand (dppd) to prepare the octahedral complexes [Al(dppd) 3 ] 3 and [Ga(dppd) 3 ]. 16 These compounds are metalloligands containing six exotopic pyridyl groups, so have the potential to act as octahedral nodes.…”

Self-assembly of [2+2] Co(II) metallomacrocycles and Ni(II) metallogels with novel bis(pyridylimine) ligands

“…It is interesting to note that the other ligands did not form any metallogel under comparable conditions as used in the case for L 4 . Presumably, for L 1 and L 3 this can be attributed to the 2-position of the nitrogen atom in the pyridyl substituents hindering the formation of polymeric fibrous complex species as it was discussed by Dudek et al for pyridyl-b-diketone ligands [47]. Since L 2 possesses 3-pyridyl substituents compared to L 4 other structural features, must be responsible for the different behavior in this case, possibly the variation in the spacer unit.…”

Crystal structures of (E)-5-(4-methylphenyl)-1-(pyridin-2-yl)pent-2-en-4-yn-1-one and [3,4-bis(phenylethynyl)cyclobutane-1,2-diyl]bis(pyridin-2-ylmethanone)

“…al., 2013), AYUYOJ (Fun et al, 2011a), BERXEC (Wang et al, 2004), CIBYIY (Brennan et al, 2018), COBJEJ (Prajapati et al, 2008), ENINOG (Lee et al, 2016), GARMAP (Fan & Wang, 2012), IJUSAI (Jasinski et al, 2011), IXOXOJ (Dudek et al, 2011), LANTAY (Qian et al, 2017), OGIZIP and VUZVET (Tan et al, 2016), PUKVEY (Rout & Mondal, 2015), QEMJOK and QEMJUQ (Albaladejo et al, 2018), SOXHAP (Lin et al, 2009), TISCEF (Jayarama et al, 2013) and YUQTEK (Li et al, 2010)] demonstrate similar conformations, but different crystal packing in the region of pyridyl ring. The majority of 1-phenyl-substituted chalcones and 1-phenyl-substituted pentenyn-1-ones also exhibit a nearly coplanar arrangement of the aryl and ketone fragments and thus no hindrance occurs between the hydrogen atoms of these fragments.…”