Synthesis, Characterization And Properties Of Acylthiourea And Their Copper Complexes

Abstract:Thiourea is a kind of thiocarbonyl compounds that can stably exist in nature. It has received considerable attention, especially in the fields of biology, chemistry, and medical industry. It is extensively accepted that the substitution of thiourea derivatives plays an important role in tuning the properties and activities of the resultant complexes. With the presence of N, O, S, and N’ donors, acylthioureas show versatile coordination behaviour in complexation and have potential application in catalysis, materials, analytical chemistry. Based on the ligand effects, the objective of this thesis is focusing on the synthesis and characterization of a series of novel acylthioureas ligands and their copper complexes, and further on the use of a part of complexes as catalyst for the C-N coupling reaction. This thesis contains two parts as follows.1. Synthesis of copper complexes bearing the novel N-(2,6-diisopropylphenyl)-N’-benzoylthiourea ligandAryl chloride (ArCO(Cl), potassium sulfocyanide (KSCN) and2,6-diisopropyl aniline were employed to synthesize N-(2,6-diisopropylphenyl)-N-benzoylthiourea ligand L1(1). Products obtained by reactions of1with Cu(Ⅰ)/Cu(Ⅱ) halides were characterized by NMR spectroscopy, FT-IR and elemental analysis, and single crystal X-ray diffraction. The reaction of1with CuCl2afforded the mononuclear Cu(Ⅰ) adduct (L1)2CuCl (3) of2:1stoichiometry by the reduction of Cu(Ⅱ) to Cu(Ⅰ). Affected by interaction in intramolecular N-H…Br hydrogen bonding, the two ligands of3forms a butterfly-like structure. The product of1and CuBr2turned out to be Cu(Ⅰ) compound of2:1stoichiometry. The dinuclear dimeric [L1BrCu(μ-L1)]2(4) exhibits the shortest Cu…Cu separation (2.6121(6) A) so far of this type. Ligand1and CuCl gave the same complex (L1)2CuCl (3), while the product of1and Cul is dimeric adduct [L1ICu(μ-L1)]2(8) with a structure resembling to that of [L’BrCu(μ-L1)]2(4). Instead, the direct reaction of1with CuBr led to the formation of adamantanoid cage (L1Cu)2(μ-L1)2Cu2(μ-Br)4(5) containing the unprecedented S2(μ-S)2Cu2(μ-Br)4core. There are two inequivalent molecules (5a and5b) in the asymmetric unit, which formed enantiomeric couple. In addition, each molecule is interconnected to its four enantiomers. Intermolecular N-H…O hydrogen bonding interactions of cages of5give rise to an infinite2-D grid with the R22(12) motif in the ac plane of the unit. In order to further understand ligand effects, we carried out reactions of its methyl analogue L2(2) with CuBr. No Cu(I) compound of1:1stoichiometry was obtained. Instead, dimeric [L2BrCu(μ-L2)]2-(6) and mononuclear (L2)3CuBr (7) were produced. These results suggest that ligand effect plays an important role in the formation and structure of complexes. All Cu(Ⅰ) compounds were used in catalytic bromobenzene and imidazole, pyrazole and3,5-dimethyl pyrazole C-N coupling reaction. No catalytic activity was found.2. Synthesis of the novel N,N-disubstituted acylthiourea ligands with their copper complexesThree kinds of aryl chloride (ArCO(Cl)), potassium sulfocyanide (KSCN) and secondary amine containing different substituents (HNRR’) were employed to synthesize a series of N,N-disubstituted acylthiourea ligands ArC(O)NHC(S)NRR’ including1) the structures containing benzene acyl:L3(9, Ar=C6H5, NRR’=NiPrPh) and L4(10, Ar=C6H5, NRR’=NPh2),2) the structures containing2,4,6-trimethyl benzene acyl: L5(11, Ar=2,4,6-Me3C6H2, NRR’=N/PrPh), L6(12, Ar=2,4,6-Me3C6H2, NRR’=NPh2), L7(13, Ar=2,4,6-Me3C6H2, NRR’=NEt2) and L8(14, Ar=2,4,6-Me3C6H2, NRR’=NiPr2),3)the structures containing1-naphthalene acyl:L9(15, Ar=C10H7, NRR’=NiPrPh), L10(16, Ar=C10H7, NRR’=NPh2), L11(17, Ar=C10H7, NRR’=NEt2) and L12(18, Ar=C10H7, NRR’=NzPr2).Monovalent anionic ligands were prepared from ligand L3-12to react with Cu(Ⅰ)/Cu(Ⅱ) halides. The deprotonation of L5(11) by using NaOAc followed with CuI afforded Cu(Ⅱ) compound trans-(L5’)2Cu (19) of2:1stoichiometry. Structure analysis showed that L5’ acts as a chelating bidentate O,S-monoanionic ligand to form six-membered ring with metal ion in trans arrangement. While the deprotonation of L9(15) by using NaOAc followed by reaction with CuCl turned out to be the adduct of Cu(Ⅱ) compound cis-(L9’)2Cu (20).2) The deprotonation of L4(10) by using EtsN followed with metathesis reaction with CuBr also afforded Cu(Ⅱ) compound ciss-(L4’)2Cu (21);3) Surprisingly, The direct reaction of L7(13) with CuCl2led to the formation of trans-(L7’)2Cu (22), which is similar to26. In sharp contrast, the reaction of L6(12) with CuBr in anhydrous ethanol solution gave a Cu(Ⅰ) complex (L6)2CuBr (23), which forms a butterfly-like structure similar to that of3. Reactions involving other ligands are too complicated to explain.