Syntheses and Characterizations of Multiply-Bonded Dichromium Complexes: From Quadruple to Quintuple Bond

• Main Authors: Chia-Wei Hsu, 許家瑋
• Other Authors: Yi-Chou Tsai
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/18939074047872713067

碩士 === 國立清華大學 === 化學系 === 96 === In this thesis, we report the syntheses and characterizations of multiply bonded dichromium complexes. Upon reduction of Cr2(��-Cl)2[(2,6-Me2C6H3)NCHN(2,6-Me2C6H3)]2(THF)2 (1) with KC8, two quintuply-bonded dinuclear chromium complexes Cr2[(2,6-Me2C6H3)NCHN(2,6-Me2C6H3)]2 (2) and Cr2[(2,6-Me2C6H3)NCHN(2,6-Me2C6H3)]3 (3) were isolated. Subsequent reduction of 3 with KC8 in the presence of cryptand-[2.2.2] led to the formation of a quintuply-bonded Cr(I)2 compound [K(cryptand [2.2.2])]{Cr2[(2,6-Me2C6H3)NCHN(2,6-Me2C6H3)]3} (4) (Cr-Cr, 1.7397(9) Å) . Complexes 2, 3, 4 have been characterized by NMR, elemental analysis and X-ray diffraction. Complexes 2 and 4 are diamagnetic and they both feature a Cr-Cr quintuple bond. Furthermore, we also synthesized a family of Cr2[ArNCRNAr]2 (Ar = 2,4,6-Me3C6H2, R = H 8; Ar = 2,6-Et2C6H3, R = H 10; Ar = 2,6-i-Pr2C6H3, R = H 12; Ar = 2,6-i-Pr2C6H3, R = CH3 14), which all display a Cr-Cr quintuple bond with Cr-Cr bond lengths in the range of 1.7395(7)-1.812(2) Å. Complexes 8, 10, 12, 14 have been characterized by NMR, elemental analysis and X-ray diffraction. In conclusion, we successfully synthesized two types of quintuply-bonded Cr-Cr complexes, the D3h symmetry complex (4) and D2h symmetry complexes (2, 8, 10, 12, 14). In addition, we isolated an unusual quadruply-bonded Cr(II)2 complex , Cr2{u-[(2-ClC6H4)NCH(tBu)N(2-ClC6H4)]Li}2{u-[(2-ClC6H4)NCH(tBu)N(2-ClC6H4)]} (16) with a nonparallel square planes of each Cr.