Ligand-Controlled Mixed-Valence Copper Rectangular Grid-Type Coordination Polymers Based on Pyridylterpyridine

摘要

Six mixed-valence Cu~ICu~(II) compounds containing 4'-(4-pyridyl)-2,2':6',2"-terpyridine (L1) or 4'-(2-pyridyl)-2,2':6',2"-terpyridine (L2) were prepared under the hydrothermal and ambient conditions,and their crystal structures were determined by single-crystal X-ray diffraction.Selection of CuCl_2centre dot2H_2O or Cu(CH_3COO)_2centre dotH_2O with the L1 ligand and NH_4SCN,Kl,or KBr under hydrothermal conditions afforded 1-dimensional mixed-valence Cu~ICu~(II) compounds [Cu_2(L1)(mu-1,1-SCN)(mu-Cl)Cl]_n (1),[Cu_2(L1)(mu-1)_2Cl]_n (2),[Cu_2(L1)(mu-Br)_2Br]_n (3),and [Cu_2(L1)(mu-1,3-SCN)_2(SCN)]_n (4),respectively.Compound 5,prepared by layering with CuSCN and L1,is a 2-dimensional bilayer structure.In compounds 1-5,the L1 ligand and X (X=Cl,Br,I,SCN) linked between monovalent and divalent copper atoms resulting in the formation of mixed-valence rectangular grid-type M_4L_4 or M_6L_6 building blocks,which were further linked by X (X=Cl,Br,I,SCN) to form 1- or 2-dimensional polymers.The sizes of M_4L_4 units in 1-4 were fine-tuned by the sizes of X linkers.Reaction of Cu(CH_3COO)_2centre dotH_2O with L2 and NH_4SCN under hydrothermal conditions gave mixed-valence Cu~ICu~(II) compound [Cu_2(L2)(mu-1,3-SCN)_3]_n (6).Unlike those in 1-5,the structure of 6 was constructed from thiocyanate groups and the pendant pyridine of L2 left uncoordinated.The temperature-dependent magnetic susceptibility studies on compounds 1 and 4 showed the presence of mixed-valence electronic structure.