Issue 8, 2011

Synthesis and X-ray crystal structures of imido and ureato derivatives of titanium(iv) phthalocyanine and their application in the catalytic formation of carbodiimides by metathesis from isocyanates

Abstract

The imido titanium phthalocyanine complex [PcTi(NDip)] (Dip = 2,6-diisopropylphenyl) 2a was synthesized from [PcTiO] 1 and one eq. of DipNCO. Due to the steric demand of the Dip group, addition of another isocyanate molecule to the Ti[double bond, length as m-dash]N functionality of 2a does not occur even at high molar ratios of DipNCO. However, 1 reacts with 2 eq. of arylisocyanates containing sterically less demanding aryl groups producing N,N′-diarylureatotitanium(IV)phthalocyanines [PcTi{κ2-(NR)C(O)(N′R)}] (R = p-tolyl (Tol) 3a or mesityl (Mes) 3b). The N,N′ coordination (III) of the ureato ligand in 3a and 3b was proven by a single set of resonances for the aryl groups in their 1H-NMR spectra. An N,O coordination (IV) can therefore be excluded. This is also confirmed by the X-ray crystal structure of 3a. Upon heating [PcTiO] and an excess of aryl isocyanates for 6 days, a steady evolution of CO2 was observed and a white precipitate, identified as the corresponding diarylcarbodiimides (V), could be isolated. Therefore this reaction was applied in the metathetic conversion of two isocyanate molecules into diarylcarbodiimides (V) and CO2. Additionally, imido titanium Pc's 2b (R = tBu) and 2c (R = Mes) were prepared by a more general synthetic strategy, reacting the potassium salt of the ligand PcK2 with appropriate imido titanium precursors.

Graphical abstract: Synthesis and X-ray crystal structures of imido and ureato derivatives of titanium(iv) phthalocyanine and their application in the catalytic formation of carbodiimides by metathesis from isocyanates

Supplementary files

Article information

Article type
Paper
Submitted
19 Jul 2010
Accepted
09 Dec 2010
First published
17 Jan 2011

Dalton Trans., 2011,40, 1787-1794

Synthesis and X-ray crystal structures of imido and ureato derivatives of titanium(IV) phthalocyanine and their application in the catalytic formation of carbodiimides by metathesis from isocyanates

W. Darwish, E. Seikel, R. Käsmarker, K. Harms and J. Sundermeyer, Dalton Trans., 2011, 40, 1787 DOI: 10.1039/C0DT00867B

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