First Examples of Homogeneous Catalytic Cyclotrimerization and Polymerization of Phenylacetylene and Copolymerization of Phenylacetylene and Norbonene with Dinuclear Complexes Containing Unbridged Metal-Metal Quadruple Bond

2003 ◽  
Vol 68 (6) ◽  
pp. 1094-1104 ◽  
Author(s):  
Konstantinos Mertis ◽  
Stavros Arbilias ◽  
Demos Argyris ◽  
Nikos Psaroudakis ◽  
Jiří Vohlídal ◽  
...  
Keyword(s):  
Dinuclear Complexes ◽  
Addition Reactions ◽  
Polymer Yield ◽  
Quadruple Bond ◽  
Metal Metal ◽  
Medium Activity ◽  
Copolymer Structure ◽  
Almost All ◽  
Ligand Addition ◽  
Low Activity

First examples of application of dinuclear complexes containing unbrigded metal-metal quadruple bond as catalysts in cyclotrimerization, oligomerization and polymerization of substituted acetylene are reported. The d4-d4 dinuclear complexes (Bu4N)2[Re2X8] (1) (1a, X = Cl; 1b, X = Br and 1c, X = I) show low activity and the complex [Mo2Cl4(MeOH)2(PPh3)2] (2) medium activity in cyclotrimerization and oligomerization of phenylacetylene (PA). In contrast, the tungsten-based d4-d4, complex Na4[W2Cl8] (3) exhibits high polymerization activity (polymer yield above 90%) and ca 75% cis-selectivity in tetrahydrofuran. The activity and cis-stereoselectivity of these single-component catalysts decrease in the order 3 >> 2 >> 1, which is proportional to the metal-metal quadruple bond propensity towards ligand addition reactions. Complex 3 induces metathesis polymerization of norbornene (NBE) to poly(cyclopentene-1,3-diylvinylene) with 82% cis-selectivity and copolymerization of PA and NBE to almost all-cis high-molecular-weight copolymer containing cyclopentene-1,3-diylvinylene units, which is free of longer sequences of both PA and NBE units. This suggests that also homopolymerization of PA with 3 proceeds by the metathesis mechanism and that the PA/NBE copolymer structure is close to the alternating one.

Metathesis Polymerization of Phenylacetylene by Tungsten Aryloxo Complexes

1995 ◽  
Vol 60 (3) ◽  
pp. 489-497 ◽  
Author(s):  
Hynek Balcar ◽  
Jan Sedláček ◽  
Marta Pacovská ◽  
Vratislav Blechta
Keyword(s):  
Molecular Weight ◽  
Catalytic Activity ◽  
Induction Period ◽  
Average Molecular Weight ◽  
Molar Fraction ◽  
Molar Ratio ◽  
Weight Average Molecular Weight ◽  
Polymer Yield ◽  
Positive Effect ◽  
Ligand Addition

Catalytic activity of the tungsten aryloxo complexes WCl5(OAr) and WOCl3(OAr), where Ar = 4-t-C4H9C6H4, 2,6-(t-C4H9)2C6H3, 2,6-Cl2C6H3, 2,4,6-Cl3C6H2, and 2,4,6-Br3C6H2 in polymerization of phenylacetylene (20 °C, monomer to catalyst molar ratio = 1 000) was studied. The activity of WCl5(OAr) as unicomponent catalysts increases with increasing electron withdrawing character of the -OAr ligand. Addition of two equivalents of organotin cocatalysts (Me4Sn, Bu4Sn, Ph4Sn, Bu3SnH) to WCl5(O-C6H2Cl3-2,4 ,6) has only slight positive effect (slightly higher polymer yield and/or molecular weight of poly(phenylacetylene)s was achieved). However, in the case of WOCl3(O-C6H3Cl2-2, 6) catalyst, it enhances the activity considerably by eliminating the induction period. Poly(phenylacetylene)s prepared with the catalysts studied have weight-average molecular weight ranging from 100 000 to 200 000. They are trans-prevailing and have relatively low molar fraction of monomer units comprised in cyclohexadiene sequences (about 6%).

The electronic nature of the metal-metal quadruple bond: variable photon energy photoelectron spectroscopy of Mo2(O2CCH3)4

1992 ◽  
Vol 114 (26) ◽  
pp. 10492-10497 ◽  
Author(s):  
Dennis L. Lichtenberger ◽  
Charles D. Ray ◽  
Frank Stepniak ◽  
Yu Chen ◽  
J. H. Weaver
Keyword(s):  
Photon Energy ◽  
Photoelectron Spectroscopy ◽  
Electronic Nature ◽  
Quadruple Bond ◽  
Metal Metal

scholarly journals Activity Profiles of Soccer Players During the 2010 World Cup

2013 ◽  
Vol 38 ◽  
pp. 201-211 ◽  
Author(s):  
Filipe Manuel Clemente ◽  
Micael Santos Couceiro ◽  
Fernando Manuel Lourenço Martins ◽  
Monika Ognyanova Ivanova ◽  
Rui Mendes
Keyword(s):  
High Activity ◽  
Soccer Players ◽  
Activity Time ◽  
Activity Profile ◽  
World Cup ◽  
Physical Demands ◽  
Fifa World Cup ◽  
Medium Activity ◽  
The Mean ◽  
Low Activity

Abstract The main objective of this study was to analyse the distance covered and the activity profile that players presented at the FIFA World Cup in 2010. Complementarily, the distance covered by each team within the same competition was analysed. For the purposes of this study 443 players were analysed, of which 35 were goalkeepers, 84 were external defenders, 77 were central defenders, 182 were midfielders, and 65 were forwards. Afterwards, a thorough analysis was performed on 16 teams that reached the group stage, 8 teams that achieved the round of 16, 4 teams that reached the quarter-finals, and 4 teams that qualified for the semi-finals and finals. A comparison of the mean distance covered per minute among the playing positions showed statistically significant differences (F(4,438) = 559.283; p < 0.001; 2 = 0.836; Power = 1.00). A comparison of the activity time among tactical positions also resulted in statistically significant differences, specifically, low activity (F(4,183.371) = 1476.844; p < 0.001; 2 = 0.742; Power = 1.00), medium activity (F(4,183.370) = 1408.106; p < 0.001; 2 = 0.731; Power = 1.00), and high activity (F(4,182.861) = 1152.508; p < 0.001; 2 = 0.703; Power = 1.00). Comparing the mean distance covered by teams, differences that are not statistically significant were observed (F(3,9.651) = 4.337; p < 0.035; 2 = 0.206; Power = 0.541). In conclusion, the tactical positions of the players and their specific tasks influence the activity profile and physical demands during a match.

scholarly journals Axial Addition in Diastereoisomeric [Ni(Me8[14]ane)](ClO4)2 Complexes and Their Antifungal Activities

2021 ◽  
Vol 41 (1) ◽  
pp. 122-147
Author(s):  
D Palit ◽  
L Dey ◽  
S Rabi ◽  
S Roy ◽  
A Alam ◽  
...  
Keyword(s):  
Phytopathogenic Fungi ◽  
Axial Ligand ◽  
Addition Reactions ◽  
Antifungal Activities ◽  
Conductance Data ◽  
Square Planar ◽  
Square Planar Complexes ◽  
Ligand Addition

A series of diastereoisomeric square planar nickel(II) diperchlorate complexes, [Ni(L)](ClO4)2{L= isomeric Me8[14]ane (LAα, LBα or LCα)}undergo axial ligand addition reactions with NO3-, Cl-, Br-, SCN- or ClO4- to yield six coordinate octahedral derivatives [NiL(X)x(Y)y].z(H2O)(X=NO3,Cl, Br or SCN; Y= ClO4; x = 1 or 2; y = 1 or 0 and z = 0, 1 or 2). The products have been characterized on the basis of analytical, spectroscopic, magnetic and conductance data. All the derivatives are unstable in open air except one derivative and revert back to original square planar complexes. Antifungal activities of the ligands and their nickel(II) complexes  have been investigated against some phytopathogenic fungi. The Chittagong Univ. J. Sci. 40(1) : 122-147, 2019

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