Syntheses,Structure And Properties Of Metal Complexes With Macrocyclic Secondary Amine N-heterocyclic Carbene Ligands

In the past years,polydentate macrocyclic NHC ligands,in which the donors could be just the NHC groups or NHC mixed with other donors,have attracted considerable interest due to their diverse coordination chemistry.To date,an increasing number of metal complexes bearing bidentate,tridentate,and tetradentate macrocyclic NHC ligands have been reported,some of which have found potential applications in homogeneous catalysts,medicine,guest recognition,and luminescence.Saturated polyamine macrocyclic compounds are among the most important macrocyclic ligands in coordination chemistry.The secondary amine usually coordinates to the metal ion as a neutral donor in the macrocyclic secondary amine ligands.However,in some cases,the secondary amine donor could be deprotonated and bonded to the metal ion as an amide donor.Considering the rich coordination chemistry of saturated polyamine macrocyclic ligands and polydentate NHC ligands,we have postulated that the combination of NHC and secondary amine donors would give macrocyclic NHC ligands with versatile coordination modes.The research presented in this thesis focused on the synthesis,characterization and coordination chemistry of Ni(II),Pd(II),Pt(II),Cu(I),Ag(I),Au(I)complexes bearing macrocyclic hybrid amine N-heterocyclic carbene ligands.The main resulst are summarized in the following:1.Synthesis of macrocyclic hybrid amine-benzimidazolium saltsFive macrocyclic hybrid amine-benzimidazolium salts with different numbers of benzimidazolium and amine units,[H2L][PF6]2(L = L1,L2,L5)and[H4L][PF6]4(L =L3,L4),have been synthesized via cyclization,detosylation,neutralization and anion-exchanged reactions.2.Synthesis,structure and luminescent properties of Ag(l)and Au(I)complexes with macrocyclic hybrid amine N-heterocyclic carbene ligandsTwelve new Ag(I)and Au(I)complexes bearing macrocyclic hybrid amine N-heterocyclic carbene ligands,have been synthesized.Ag complexes[Ag3(L1)2][PF6]3(1),[Aga(L2)2(CH3CN)2][PF6]4(2),[Ag(H2L3)][PF6]3(3)[Ag2(H2L3)][PF6]4(4)[Ag3(L5)][PF6]3(5)and[Ag3(L5)2(CH3CN)2][PF6]3(6)have been obtained from the reactions of the NHC precursors and Ag2O in acetonitrile.Au complexes[Au2(L1)2](PF6)2(7),[Au2(L2)2](PF6)2(8),[Au(H2L3)][PF6]3(9),[Au3(L3)(Cl)2][PF6](10),[Au2(L4)][PF6]2(11)and[Au2(L5)2][PF6]2(12)have been prepared by reacting the NHC precursors and AuCl(SMe2)or transillmetation reactions.Molecular structures of all complexes are established by single-crystal X-ray diffraction studies.Metal ions in Ag(i)complexes 1-3 and Au(I)complexes 9-11 are coordinated with two macrocyclic NHC ligands to form a sandwiched structure.In contrast,metal ions in Ag(I)complexes 4-6 and Au(I)complexes 7,8 and 12 are located in the cavity of one macrocyclic ligand.The photoluminescent properties of Au(I)complexes 9-12 have also been investigated.3.Synthesis,structure and luminescent properties of amine-bis(N-heterocyclic carbene)Cu(I)ComplexesDinuclear Cu(I)complexes bearing hexadentate,macrocyclic N-heterocyclic carbene(NHC)ligands,[Cu2(L3)(CH3CN)][PF6]2(13),[Cu2(L4)(CH3CN)]2[Cu2(L4)(CH3CN)2][PF6]6(14)have been synthesized by the reactions of[H4L][PF6]4(L = L3,L4)with excess Cu2O in acetonitrile.Recrystallizations of the heat-treated sample of 13 and 14 from suitable solvents result in.[Cu2(L3)][PF6]2(15)and[Cu2(L4)][PF6]2(16).The mechanochromic luminescent properties of 13-16 have been studied.After grinding in a mortar,a significant emission color change is found with a red-shift of 98 nm for 13,80 nm for 14,20 nm for 15,and 64 nm for 16,respectively.This mechanochromic transformation is found to be a cry stall ine-to-amorphous conversion,which can be reverted by converting the amorphous solids to the original crystalline states through adding drops of organic solvent or recrystallization.The possible correlations between the luminescent properties and structural modifications such as Cu-Cu distances have been discussed.In order to further study the luminescent properties of Cu(I)complexes with[(NHC)2Cu(N)]+moiety,we prepared two amine-bis(N-heterocyclic carbene)ligand precursors[H2L6][PF6]2 and[H2L7][PF6]2,from which Ag(I)and Cu(I)complexes[Ag3(L6)2][PF6]3(17),[Ag3(L7)2][PF6]3(18),[Cu(L6)][PF6](19)and[Cu(L7)][PF6](20)have been synthesized by reactions of these precursors with Ag2O and Cu2O,respectively.Complexes 19 and 20 can also be obtained by transmetalation of 17 and 18,respectively,with 3.0 equiv of CuCl.A heterometallic Cu/Ag-NHC complex[Cu2Ag(L6)2(CH3CN)2][PF6]3(21)is formed by the reaction of 17 with 2.0 equiv of CuCl.The luminescent properties of 19-21 in solution and the solid state have been studied.At room temperature,19-21 exhibit evident luminescence in the solid state and solution state.The emission wavelengths of 19-21 are found to be at 483 nm in CH3CN,but they are 484,480 and 592 nm in the solid state for 19-21,respectively.These results suggest that 21 dissociates into two molecules of 19 and Ag(I)ion in solution.Complex 21 is the first luminescent heterometallic Cu/Ag-NHC complex.4.Synthesis,structural characterization and NMR studies of group 10 metal complexes with macrocyclic amine N-heterocyclic carbene ligandsA series of Ni(II),Pd(II)and Pt(II)complexes[ML][PF6]2[L = L1,M = Ni(22),Pd(23),Pt(24);L = L2,M = Ni(25),Pd(26),Pt(27)]and[Pt(L2)(acac)](28)have been prepared by the reactions of two tetradentate macrocyclic amine-NHC ligand precursors,[H2L1][PF6]2 and[H2L2][PF6]2,with Ni(OAc)2·4H20,Pd(OAc)2 and Pt(acac)2 in the presence of NaOAc.Complex 28 is isolated along with 27 from the same reaction between[H2L2][PF6]2 and Pt(acac)2.There are two atropisomers in 22-24 and two achiral conformers in 25-27.The crystal structures of 22-25 and one conformer of 25-27(25a-27a)have been determined by single-crystal X-ray diffraction studies.The metal ion is found to reside in the cavity of the macrocyclic ring and adopts square-planar configuration.Detailed NMR studies including variable-temperature NMR spectra reveal a dynamic interconverting process between two atropisomers of 22-24 in the solutions via a ring twisting mechanism.Two conformers in the equilibrated solution of 25-27,probably arising from the orientation of two amine N-H bonds with respect to the coordination plane,exchange slowly.Time-dependent 1H NMR spectra show that one conformer(25a-27a)in solution converts into the other(25b-27b)via the inversion of nitrogen atom.5.Synthesis and structure of Ni(II)and Pd(II)complexes with a hexadentate macrocyclic diamine-tetracarbene ligandCoordination chemistry of macrocyclic N-heterocyclic carbene(NHC)ligand precursor[H4L][PF6]4(L = L3,L4)has been studied by the synthesis of its Ni(II)and Pd(II)complexes.Reactions of[H4L][PF6]4(L = L3,L4)with Ni(OAc)2 and Pd(OAc)2 in the presence of NaOAc yield[Ni(L)][PF6]2(L=L3,29;L = L4,30),[Pd(L)][PF6]2(L=L3,31;L = L4,32),[Ni2(L-2H)][PF6]2(L=L3,33;L = L4,34)and[Pd2(L-2H)][PF6]2(L = L3,35;L = L4,36),respectively.33 is also formed by the reaction of 29 with 1.0 equiv of Ni(OAc)2·4H2O in the presence of NaOAc.Transmetallation of 4 with two equiv of Ni(PPh3)2Cl2 gives[Ni2(L3)(μ-O)](PF6)2(37),the first example of a dinuclear Ni(II)complex with a singly bridging oxo group.37 is converted to 33 in good yield through the treatment with NaOAc.