Search results for "Polymerization"

A Bis(tridentate)cobalt Polypyridine Complex as Mediator in Dye‐Sensitized Solar Cells

2015

Dye-sensitized solar cells equipped with cationic and neutral RuII-based sensitizers [Ru(ddpd){tpy(COOH)3}]2+ [12+; ddpd = N,N′-dimethyl-N,N′-di(pyridin-2-yl)pyridin-2,6-diamine, tpy(COOH)3 = 2,2″6′,2″-terpyridine-4,4′,4″-tricarboxylic acid] and [Ru(ddpd){tpy(COOH)(COO)2}] (2) with and without the coadsorbent chenodeoxycholic acid were constructed with I3–/I– or the CoIII/II-based redox mediators [Co(bpy)3]3+/2+ (33+/2+; bpy = 2,2′-bipyridine) and [Co(ddpd)2]3+/2+ (43+/2+) in the presence of LiClO4 and 4-tert-butylpyridine. The best photovoltaic performance was achieved by using the 43+/2+ shuttle and the neutral sensitizer 2 without coadsorbent. The higher short-circuit photocurrent densit…

Novel Alkylanthracenes Synthesis, Reductive Alkylation, and Reductive Polymerization

1988

A series of novel substituted anthracenes has been prepared which carry two or four n-alkyl groups at C-2 and C-3 (C-6 and C-7). The route taken includes the synthesis of novel 2,3-dialkylbutadienes, their Diels-Alder reaction with 1,4-benzo- or 1,4-naphthoquinone, the dehydrogenation of the adducts, and the reduction of the anthraquinones. The substituted anthracenes are submitted to reduction and reductive alkylation in ethereal solvents and in liquid ammonia to yield 9,10-dialkyl-substituted 9,10-dihydroanthracenes. A modification of the reductive alkylation, i.e. the introduction of 1,n-dihaloalkanes as electrophiles, provides polymeric chains, in which dihydroanthracene moieties are li…

Enhancing Performance of a Bis(arylimino)pyridine‐Iron Precatalyst for Ethylene Polymerization by Substitution with a 2,4‐Bis(4,4′‐dimethoxybenzhydry…

2021

A series of unsymmetrical 2-(2,4-bis(bis(4-methoxyphenyl)methyl)-6-MeC6H2N)-6-(1-(arylimino)ethyl)pyridine-iron halides has been synthesized and characterized. The molecular structure of two representative species was determined by the single-crystal X-ray diffraction. Activated with either MAO or MMAO, the precatalysts displayed high activity, reaching 2.19×107 g PE (mol Fe)−1 h−1 at 60 °C in ethylene polymerization. The microstructural analysis of the polymers obtained indicates highly linear polyethylene containing a vinyl chain end.

Solution Chemistry of Element 106:  Theoretical Predictions of Hydrolysis of Group 6 Cations Mo, W, and Sg

2001

Fully relativistic molecular density-functional calculations of the electronic structure of hydrated and hydrolyzed complexes have been performed for the group 6 elements Mo, W, and element 106, Sg. By use of the electronic density distribution data, relative values of the free energy changes and constants of hydrolysis reactions were defined. The results show hydrolysis of the cationic species with the formation of neutral molecules to decrease in the order Mo > W > Sg, which is in agreement with experiments for Mo, W, and Sg. For the further hydrolysis process with the formation of anionic species, the trend is reversed:  Mo > Sg > W. A decisive energetic factor in the hydrolysis process …

Magnetic Molecular Rectangles Constructed from Functionalized Nitronyl‐Nitroxide Ligands and Lanthanide(III) Ions

2020

Metal complexes of a picolinate-based nitronyl nitroxide free radical.

2009

A nitronyl nitroxide free radical containing an appended picolinate moiety was synthesized. The resulting tridentate ligand picNN forms neutral mononuclear metal complexes of formula [M(picNN)(2)].3H(2)O (M = Mn, Co, Ni, Zn). These compounds are isostructural and crystallize in the orthorhombic Pnna space group. The metal complexes have a C(2) symmetric structure, with the metal centers lying on the binary axis and surrounded by two equivalent picNN radicals. The magnetic properties of this family of compounds indicate the presence of very strong metal-radical exchange interactions, ranging from J(Ni-rad) = -193 cm(-1) to J(Mn-rad) = -98 cm(-1). Relatively weak (J(rad-rad) = -15 cm(-1)) thr…

Thiophen—Mangantricarbonyl-Komplexe

1967

Abstract Cationic thiophenemanganese tricabonyl complexes of the formula [C 4 (CH 3 ) x H 4- x S Mn(CO) 3 ] + have been prepared with 2-methyl-, 3-methyl-, 2,5-dimethyl-, 2,3,5-trimethyl-, tetramethylthiophene, and with thiophene by the reaction of Mn(CO) 5 Cl+AlCl 3 or AlBr 3 with the thiophenes in petrol ether, at 100–110°. The complexions give yellow solutions which are fairly stable. Their IR and some NMR spectra are given and discussed.

A black-box approach to the construction of metal-radical multispin systems and analysis of their magnetic properties

2020

An interaction of M(hfac)2 (M = Mn or Ni) with N-(bis(4,4,5,5-tetramethyl-3-oxido-1-oxyl-4,5-dihydro-1H-imidazol-2-yl)methylene)-2-methyl-propan-2-amine oxide (a nitronyl nitroxide diradical with theC[double bond, length as m-dash]N(O)-tert-Bu coupler) was investigated under various conditions. It was found that prolongation of reaction time caused transformation of the initial diradical into new diradicals with the uniqueC[double bond, length as m-dash]N-OH coupling unit and formation of binuclear Mn(ii) and Ni(ii) complexes, which were characterized by X-ray diffraction analysis. The resulting binuclear heterospin complexes have a complicated magnetic structure with six paramagnetic cente…

General Kinetic Analysis and Comparison of Molecular Weight Distributions for Various Mechanisms of Activity Exchange in Living Polymerizations

1997

The molecular weight distributions in many living (e.g. anionic, group transfer, cationic, and radical) polymerizations strongly depend on the dynamics of various equilibria between chain ends of d...

Synthesis, Spectroscopic Characterization, and Crystal Structure Determination of Cationic [(Cyclopentadienyl)dicarbonyliron](alkynyl)‐aminocarbene C…

1996

(Alkynoyl)iron complexes 1, Cp(CO)2Fe(OCCCR) (R = CH3, Ph, SiMe3), were synthesized by applying a mixed anhydride procedure and transformed into the cationic methoxycarbene complexes 2, [Cp(CO)2 Fe(C(OMe)CCR)+]-[PF6–]. Primary amines H2NR′ react with the methoxycarbene complexes to furnish exclusively cationic aminocarbene complexes 3, [Cp(CO)2 Fe(C(NHR′)CCR)+][PF6–], or (2-methoxyvinyl)aminocarbene complexes 5. The spectroscopic properties of the new complexes are discussed. The (alkynyl)-aminocarbene complexes 3e and 3f were characterized by X-ray crystal structure analysis.