大会报告师范-段天宇

1、Synthesis and Characterization of Coordinatively Unsaturated Bimetallic Units不饱和双金属螯合单元的合成与表征Tianyu Duan1, Javier Grajeda2, Dino Villagrn2*1College of Chemistry, Beijing Normal University, 2Department of Chemistry, The University of Texas at El PasoIntroductionThe unique properties, including ultra-

2、short metal-metal bond lengths and high bond orders, of coordinatively unsaturated bimetallic systems with multiple metal-metal bonds have attracted growing attention. Photo-electron spectrum (PES) of Re2Cl82-In 1964, Cotton et al presented the first strong evidence for the notion of metalmetal 242

3、quadruple bonding in Re2Cl82 molecular units。IntroductionIn 2005, Power et al reported the first bimetallic compound with a fivefold bond order and an ultra-short CrCr bond length .The first complex with a fivefold bond orderPower et al. Science 2005, 310, 844CrCr = 1.8351(4) 2022/7/25IntroductionIn

4、troduction Since then, bimetallic systems of Cr or Mo with a fivefold bond order have been synthesized and studied. Tsai et al. J. Am. Chem. Soc. 2009, 131, 12434 Tsai et al. Angew. Chem. Int. Ed. 2008, 47, 9933 Kempe et al. Z. Anorg. Allg. Chem. 2009, 635, 1149IntroductionSterically demanding suppo

5、rting ligands such as bis-diisopropylphenyl formamidine (HDippF) and bis-diisopropylphenyl guanidine (HDippG) are used to prevent more than two ligands to surrounding the bimetallic unit.In amidinates, a two-wings-up arrangement allows the wings to be put further down, aligning the N-centred lone pa

6、irs to provide shorter metalmetal bonds. In guanidinates, the steric pressure on top of the ligand initiates a process that pushes the wings down, resulting in a further shortening of the CrCr distance.Kempe et al. Nature Chem. 2009, Oct., 529-536 IntroductionMuch work remains to be done: 1. underst

7、anding the structure of such CrCr and MoMo compounds. 2. Research of WW compounds with a fivefold bond order.Understanding the structure of such bimetallic compounds with a fivefold bond order will lead to: 1. An enhanced understanding of chemical bonding. 2. Possible future applications as molecula

8、r catalysts.HypothesisSynthesis of bimetallic units with fivefold bolds of Mo and W utilizing ligands DippF- and DippG- : 1. the reported compounds Mo2(DippF)2, 2. the new Mo-Mo compound with DippG- , and the unexplored W-W compounds with ether ligand. Characterization of these compounds to understa

9、nd the structure of them. (NMR spectroscopy, X-ray crystallography and PES)Further understanding of how the three metals behave in such compounds, as well as how the two ligands influence the structure of such compounds.2022/7/25Synthesis of ligandsKrahulic et. al. J. Am. Chem. Soc. 2005, 127, 41424

10、143.2022/7/25Ge et. anometallics 2008, 27, 31313135.Synthesis of ligandsNSynthesis of Mo-Mo compounds2022/7/25Synthesis of Mo2Cl6(THF)31. Poli et. al. Eur. J. Inorg. Chem. 2001, 2001, 26992703.2. Boyd, I.; Wedd, A. Aust. J. Chem. 1976, 29, 18291832.Sn, Et2O2022/7/25Synthesis of Mo-Mo compoundsMo2Cl6

11、(THF)3 is reduced by Zn powder, then the lithium salt of HDippF or HDippG is added.ResultsMo2(DippF)2Cl3Li has been synthesized through a modified literature procedure.ResultsMo2(DippG)2Cl2 has been synthesized.ResultsTwo new compounds with a quadruple W-W bond has been synthesizedC2/c Z =16a = 39.0

12、239(1) b = 28.9800(9) c = 30.0552(1) = 90 = 125.01 = 90wR2 = 0.1653WW = 2.2574(6) Two new compounds with a quadruple W-W bond has been synthesizedResultsConclusionMo2(DippF)2Cl3Li, has been synthesized utilizing a modified literature procedure. Mo2(DippG)2Cl2 has been synthesized. W2(DippF)2Cl4Li(TH

13、F)4 and W2(DippF)2Cl3Li have been prepared.Reduction of Mo2(DippF)2Cl3Li has been tried to synthesize Mo2(DippF)2. purification and characterization of products are needed.Further purification and reduction are demanded for Mo2(DippG)2Cl2 , W2(DippF)2Cl4Li(THF)4 and W2(DippF)2Cl3LiFuture workStructu

14、ral characterization (NMR spectrascopy and x-ray crystallography) and further reduction of the Mo2(DippG)2Cl2 and the two WW compoundsReduction of Mo2(DippF)2Cl3Li, Mo2(DippG)2Cl2 , W2(DippF)2Cl4Li(THF)4 and W2(DippF)2Cl3Li to synthesize compounds M2L2 which are supposed to have a fivefold bond order.Ground-state electronic configuration of these s