Dimolybdenum Complexes Containing Pairs of N,N'-di(6-methyl-2-pyridyl)formamidine and Carboxylate Ligands

• Main Authors: Hsiao-Yun Weng, 翁曉芸
• Other Authors: Jhy-Der Chen
• Format: Others
• Language: en_US
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/85379026749556935331

碩士 === 中原大學 === 化學研究所 === 90 === Abstract. The coordination chemistry of dimolybdenum complexes containing pairs of the anion of N, N’□di(6□methyl□2□pyridyl)formamidine (DMepyF□) and carboxylate ligands are discussed. One of the starting materials Mo2(O2C(CH2)nCH3)4 (n = 8, 1) is a liquid crystalline material. Complex 1 conforms to the triclinic, crystal system space group P1, with a = 5.4439 (5), b = 14.481 (2), c = 16.154 (2) Å, □ = 63.722 (8), □ = 85.089 (6), □ = 82.348 (9)o with Z = 1. Reactions of Mo2(O2C(CH2)nCH3)4 with HDMepyF in CH2Cl2 afforded complexes of the type Mo2(O2(CH2)nCH3)2(DMepyF)2 (n = 2, 2; n = 5, 3; n = 8, 4; n = 14, 5). Their structures have been determined by X□ray crystallography. Complex 2 is monoclinic, space group P21/n, with a = 9.881 (1), b = 9.471 (1), c = 18.599 (2) Å, □ = 95.39 (1)o with Z = 2. Complex 3 is triclinic, space group P , with a = 8.616 (2), b = 9.652 (2), c = 13.337 (3) Å, □ = 89.082 (2), □ = 85.040 (2), □ = 69.827 (2)o with Z = 1. Complex 4 is triclinic, space group P , with a = 8.6609 (6), b = 9.6515 (7), c = 15.6103 (11) Å, □ = 78.4120 (10), □ = 82.2360 (10), □ = 69.6900 (10)o with Z = 1. Complex 5 is triclinic, space group P , with a = 8.5717 (6), b = 9.6087 (7), c = 19.287 (2) Å, □ = 89.925 (2), □ = 86.108 (2), □ = 69.9560 (10)o with Z = 1. The molecular structures of complexes 2 □ 5 consist of two quadruply bonded molybdenum atoms which are spanned by two trans bridging formamidanate ligands and two trans bridging carboxylate ligands. The formamidinate ligands are coordinated to the Mo centers in bidentate fashions via the two central nitrogen atoms and the terminal nitrogen atoms of the two dangling pyridine ring are located in a trans configuration, resulting in a Mo···N and a Mo···H□C axial interactions for each DMepyF□ ligand. Reactions of complex 3 or 4 with HBF4 in CH2Cl2/CH3CN afforded the complex trans□Mo2(H2DMepyF)2(CH3CN)4(BF4)6, 6. Complex 6 crystallized in two different crystal systems. Complex 6a, trans□Mo2(H2DMepyF)2(CH3CN)4(ax□CH3CN)2(BF4)6 · 2CH2Cl2, is orthorhombic, space group Pbca, with a = 18.527(3), b = 16.565 (3), c = 21.010 (2) Å, with Z = 4. Complex 6b, trans□Mo2(H2DMepyF)2(CH3CN)4(ax□BF4)2(BF4)4 · 2CH2Cl2, is monoclinic, space group C2, with a = 23.269 (5), b = 13.416 (2), c = 10.4359 (13) Å, □ = 110.53 (1)o with Z = 2. The molecular structures of complexes 6 consist of two quadruply bonded molybdenum atoms which are spanned by two trans bridging formamidinate ligands and coordinated by four trans CH3CN. They are the first dimolybdenum complexes, which contain trans, protonated formamidinate and trans CH3CN ligands. The difference between 6a and 6b is that complex 6a contains two CH3CN molecules as axial ligands, while 6b contains two BF4□ anions as axial ligands.