• Bulletin of the Korean Chemical Society
• /
• v.29 no.9
• /
• pp.1819-1822
• /
• 2008

• Polymer(Korea)
• /
• v.30 no.1
• /
• pp.64-69
• /
• 2006

A series of dinuclear half-sandwich titanium complexes with aryloxy substituent at titanium$[(\eta^5-cyclopentadienyl)(aryloxy)TiCl_2]_2[(CH_2)_n]$ (n=3, n=6, n=9) have been successfully synthesized and their styrene polymerization properties have been investigated. All complexes are characterized by $^1H\;NMR,\;^{13}C\;NMR$, elemental analysis, and mass spectrometry. In order to examine the catalytic properties of the dinuclear complexes styrene polymerization has beer conducted in the presence of MMAO. It was found that (i) all the prepared complexes were very effective catalyst for the production of SPS (syndiotactic polystyrene), (ii) the complex with the longest bridge between the two active sites exhibited greatest catalytic activity among the three catalysts, but produced SPS with the smallest molecular weight, (iii) the activities of dinuclear half-titanocens with aryloxy substitution at titanium metal were greater than those of the chloride substituted compounds. These results indicate that not only the nature of the bridge between the two active sites but also the property of substituents at the metal exert a significant influence on the polymerization behaviors of the dinuclear half-titanocene.

• Bulletin of the Korean Chemical Society
• /
• v.18 no.6
• /
• pp.618-622
• /
• 1997

The polysiloxane-bridged dinuclear metallocenes $[(SiMe_2O)_n-SiMe_2(C_5H_4)_2][(C_9H_7)ZrCl_2]_2$ (n=1 (7), 2 (8), 3 (9)) have been generated as a model complex for the immobilized metallocene at silica surface by treating the respective disodium salts of the ligands with 2 equivalents of $(C_9H_7)ZrCl_3$ in THF. All three complexes are characterized by $^1H$ NMR and measurement of metal content through ICP-MS. It turned out that the values of ${\Delta}{\delta}=[{\delta}_d-{\delta}_p]$, the chemical shift difference between the distal $({\delta}_d)$ and proximal $({\delta}_p)$ protons, for the produced dinuclear compounds (0.47 for 7, 0.49 for 8, and 0.5 for 9) were larger than the Δδ value of the known ansa-type complex holding the same ligand as a chelating one, that is just the opposite to the normal trend. In order to compare polymerization behavior of the dinuclear metallocene with the corresponding mononuclear metallocene, (Cp)$(C_9H_7)ZrCl_2$ was separately prepared. To investigate the catalytic properties of the dinuclear complexes and mononuclear metallocenes ethylene polymerization has been conducted in the presence of MMAO. The polymerization results display the typical activity dependence on polymerization temperature for all complexes. The most important feature is that the polymers from the dinuclear metallocenes represent enormously improved molecular weight compared with the polymer from the corresponding mononuclear metallocene. In addition, the influence of the nature of the bridging ligand upon the reactivities of the dinuclear metallocenes has also been observed.

• Bulletin of the Korean Chemical Society
• /
• v.29 no.9
• /
• pp.1803-1806
• /
• 2008

• Bulletin of the Korean Chemical Society
• /
• v.25 no.7
• /
• pp.1012-1019
• /
• 2004

The synthesis of novel group 9 metal complexes containing the S,S'-chelate ligands, $Li_2S_2C_2B_{10}H_{10}$ (2a) and $LiS(S=PMe_2)C_2B_{10}H_{10$} (2b), is described. Two new dinuclear complexes of the type $[{(cod)M}_2(S,S'-S_2C_2B_{10}H_{10})]$ (cod = 1,5-cyclooctadiene; M = Rh (3a), or Ir (3b)) were synthesized by the reaction of chloridebridged dimers $[M({\mu}-Cl)(cod)]_2$ with one molar equivalent of the corresponding dilithium dithiolato ligand $Li_2S_2C_2B_{10}H_{10}$ (2a). X-ray crystal structure analysis of 3a revealed a dinuclear structure in which each (cod)Rh unit is attached to a distinct sulfur atom of a 1,2-dithio-o-carboranyl ligand (2a). Additionally, the electrochemical properties of 3a and 3b were investigated by cyclic voltammetry. In an analogous manner, reaction of the lithium dithiolato ligand $LiS(S=PMe_2)C_2B_{10}H_{10}$ (2b) with $Cp^{\ast}CoI_2(CO)$ produced a mononuclear dithiolato complex, $[Cp^{\ast}CoI{(S,S'-S(S=PMe_2)C_2B_{10}H_{10})}]$ (4), which was characterized by single-crystal X-ray analysis.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.3
• /
• pp.725-730
• /
• 2013

An investigation of the coordination behavior of sulfur-containing mixed-donor tribenzo-macrocycles $L^1-L^3$ ($L^1$: 20-membered $O_3S_2$, $L^2$: 20-membered $O_2S_3$, and $L^3$: 23-membered $O_4S_2$) with $d^{10}$-metal ($Ag^+$, $Hg^{2+}$, and $Pb^{2+}$) salts is reported. The X-ray structures of five complexes (1-5) with different structural types and stoichiometries, including mono- to dinuclear species have been determined. Reactions of $L^2$ and $L^3$ with the silver(I) salts ($PF_6{^-}$ and $SCN^-$) afforded two dinuclear 2:2 (metal-to-ligand) complexes with different arrangements: a sandwich-type cyclic dinuclear complex $[Ag_2(L^2)_2](PF_6)_2{\cdot}3CH_2Cl_2$ (1) and a linear dinuclear complex $[Ag_2(L^3)_2(SCN)_2]$ (2), in which two monosilver(I) complex units are linked by an Ag-Ag contact. Reactions of $L^1$ and $L^2$ with mercury(II) salts ($SCN^-$ and $Cl^-$) gave a mononuclear 1:1 complexes $[Hg(L^1)(SCN)_2]$ (3) and $[Hg(L^2)Cl_2]$ (4) with anion coordination in both cases. $L^2$ reacts with lead(II) perchlorate to yield a mononuclear sandwich-type complex $[Pb(L^2)_2(ClO_4)_2]$ (5), giving an overall metal coordination geometry of eight with a square antiprism arrangement. From these results, the effects of the donor variation and the anioncoordination ability on the resulting topologies of the soft metal complexes are discussed.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.4
• /
• pp.1329-1332
• /
• 2012

• Bulletin of the Korean Chemical Society
• /
• v.32 no.8
• /
• pp.2617-2622
• /
• 2011

Two new Zn(II) complexes, $[Zn_2(dpa)_2(phen)_2(H_2O)_2]{\cdot}H_2O$ (1) (dpa = dephenate, phen = 1,10-phenanthroline) and [$Zn_2(dpa)_2(bpy)_2(H_2O)_2$] (2) (bpy = 2,2'-bipyridine) have been synthesized and characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis, and single crystal X-ray diffraction. The X-ray analysis reveals that the structures of 1 and 2 are dinuclear zinc(II) complexes bridged by dpa dianions, respectively. The zinc ions in 1 exhibit a distorted square pyramidal environments, while the zinc ions in 2 exhibit a trigonal bipyramid geometry. In each complex, the dpa ligand is coordinated to zinc ions as a bis-monodentate.

• Polymer(Korea)
• /
• v.24 no.2
• /
• pp.159-167
• /
• 2000

The polymethylene-bridged dinuclear half-titanocenes [(CH$_2$)$_{n}$(C$_{5}$ H$_4$)$_2$][TiCl$_3$]$_2$ (n=5(10), 7(11), 9(12)) have been synthesized by treating the distannylated derivatives of the ligands with two equivalents of TiCl$_4$ in toluene. All complexes are characterized by IR, $^1$H NMR, $^{13}$ C NMR and mass spectrometry. In order to examine the catalytic properties of the dinuclear complexes styrene polymerization has been conducted in the presence of MMAO. From the polymerization experiments it was found that ( i ) all the prepared complexes 10-12 produced syndiotactic polystyrenes, ( ii ) the complex 12 holding the longest bridging ligand exhibited the highest activity but produced a polymer having the smallest molecular weight among the polymethylene-bridged dinuclear half-titanocenes. This behavior was attributed to the influence of electron-donating caused by the polymethylene bridge between two active centers as well as the effect of steric congestion around metal center caused by the proximal distance between two active sites.s.

• Polymer(Korea)
• /
• v.30 no.5
• /
• pp.432-436
• /
• 2006

The new dinuclear CGC (constrained geometry complexes) with indenyl and methyl sub-stituted indenyl and polymethylene bridge have been synthesized, and the copolymerization of ethylene and styrene has been studied in the presence of methylalumionoxane. The activity of 12-methylene and 9-methylene bridged dinuclear CGC were 4 times higher than that of 6-methylene bridged dinucleay CGC. This result might be understood by the implication that the steric effect rather than the electronic effect nay play a major role to direct the polymerization behavior of the dinuclear CGC. The dinuclear CGCs are very efficient to incorporate styrene in backbone. The styrene contents in the formed co-polymers ranged from 6 to 45 mol% according to the polymerization conditions. The melting temperature of copolymers disappeared at high content of styrene (about 11 mol%) There is no styrene-styrene diblock sequence in copolymers. This result Indicates that the dinuclear CGC are very effective to generate random copolymer of ethylene and styrene.