Synthetic and metal organic photochemistry in industry

Roloff, Achim; Meier, Kurt; Riediker, Martin

doi:10.1351/pac198658091267

Cited by 90 publications

(43 citation statements)

References 20 publications

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“…Product studies and trapping experiments with 2,2,6,6-tetramethylpiperidine N-oxide (TMPO) have, however, indicated that titanocenes with perfluorinated Ph groups behave quite differently [4]. Since no organic radicals could be trapped, the question arose by which mechanism the fluorinated diphenyltitanocenes initiated polymerization.…”

Section: Photochemical Ring Slippage Of Bis(pentafluoropheny1)titanocmentioning

confidence: 99%

Photochemical Ring Slippage of Bis(pentafluorophenyl)titanocene: Reaction kinetics and matrix isolation of the primary photoproduct

Klingert

Roloff

Urwyler

et al. 1988

Helvetica Chimica Acta

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Laser flash photolysis and matrix-isolation techniques were applied to elucidate the photochemistry of the orange complex bis(pentafluoropheny1)titanocene ( = bis(q '-cyclopentadienyl)bis(pentafluorophenyl)titanium-(IV), Cp2Ti1V{C,Fs}2, Cp = q5-C,H,, 1) which is used as a polymerization photo-initiator. The primary photoreaction of 1 is the formation of a highly reactive blue isomer X with unit quantum yield. In carefully dried and degassed benzene solution, the photoisomer X rearranges to starting material 1 with a first-order reaction, k = 5 . 10' s-' at room temperature. X is highly reactive towards H,O, MeOH, acetone, MeCN, MeN02, butane-1,4-diyl diacrylate, 2,2,6,6-tetramethylpiperidine N-oxide, CO, O,, and N2; ahsolute bimolecular rate constants range from lob to 10' M-' . s-'. The primary photoisomerization l-+X is tentatively ascribed to acyclopentadienyl ring slippage from q 5 to a lower hapticity, a process that opens up coordinative unsaturation.Introduction. -Low-valent organotitanium complexes are capable of nitrogen fixation [l] and are well-known as polymerization catalysts [2]. The photoreactions of Ti complexes have been studied rather extensively, and this work has been reviewed [3] but, surprisingly, flash photolysis has so far not been applied to a direct kinetic and spectrographic observation of the relevant reactive intermediates. We have investigated the primary photoprocesses of bis(pentafluoropheny1)titanocene ( = bis(r '-cyclopentadienyl)bis(pentafluorophenyl)titanium(IV), Cp,Ti1V{C,F5),, Cp = 9 '-C,H,, 1) by flash photolysis and matrix-isolation techniques in order to elucidate the mechanism by which 1 acts as a photo-initiator used for integrated circuit fabrication [4-81.

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Section: Photochemical Ring Slippage Of Bis(pentafluoropheny1)titanocmentioning

confidence: 99%

Photochemical Ring Slippage of Bis(pentafluorophenyl)titanocene: Reaction kinetics and matrix isolation of the primary photoproduct

Klingert

Roloff

Urwyler

et al. 1988

Helvetica Chimica Acta

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“…[37][38][39][40] A radically different class of cationic photoinitiators was developed by workers at the Ciba-Geigy Corporation. [41][42][43] Ferrocenium salts (XI) undergo photolysis to generate an iron-based Lewis acid with the loss of the arene ligand (eq 16). Coordination of this latter species with an epoxide monomer is followed by ring-opening polymerization.…”

mentioning

confidence: 99%

The discovery and development of onium salt cationic photoinitiators

Crivello

1999

J. Polym. Sci. A Polym. Chem.

457

170

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“…The absorption spectrum of complex (I) is similar to those all five ironarene complexes studied. 15 proposed a mechanism for the initiation in epoxide photopolymerization with the iron-arene complex as a photoinitiator, as shown in Scheme 1. epoxides during the photolytic step, is formed. Ring opening and polymerization reaction could thus start in the ligand sphere of the iron cation leading to cyclopolyethers.…”

Section: Resultsmentioning

confidence: 99%