Mastering the Third Dimension of Salicylaldimine‐Type Ligand Systems: Development of a Convenient Route to Bis(“ferrocene–saliminato”)zirconium Chemistry

Niemeyer, Jochen; Kehr, Gerald; Fröhlich, Roland; Erker, Gerhard

doi:10.1002/chem.200801221

Cited by 27 publications

(15 citation statements)

References 30 publications

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“…Both as-formed neutral bimetallic and ionic trimetallic species are NLO active chromophores showing large quadratic hyperpolarisability β values [13,30,33]. Encouraged by these results, we pursued our efforts in this field of three-dimensional architectures [43] in which a ferrocene donor unit is connected through the π-electron system of a planar metallo-salen-type framework to an electron withdrawing group borne by the salicylidene ring. Thus, a family of four new D-π-A organometallic-inorganic hybrids obtained via zinc(II)-, copper(II)-and cobalt(II)-mediated template reaction was designed and their structural, electronic and NLO properties studied.…”

Section: Introductionmentioning

confidence: 99%

Transition metal(II) complexes featuring push-pull dianionic Schiff base ligands: synthesis, crystal structure, electrochemical, and NLO studies

Celedón

Roisnel

Carrillo

et al. 2020

Journal of Coordination Chemistry

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The present study reports the synthesis and characterization of a family of three new neutral Zn(II), Cu(II), Co(II) bimetallic (2-4) and one ionic Co(II) trimetallic (5) complexes of ferrocene-containing unsymmetrically-substituted N 2 O 2 tetradentate Schiff base ligands. They were all prepared via a three-component one-pot template reaction involving the 4hydroxyphenyl substituted ferrocenyl-containing half unit Fc-C(=O)CH=C(4-C 6 H 4 OH)NH-CH 2 CH 2 NH 2 (Fc = ferrocenyl = (η 5 -C 5 H 5 )Fe(η 5 -C 5 H 4 )), metal(II) acetate and 5nitrosalicylaldehyde (for 2-4) or the organometallic salicylaldehyde [Cp*Ru(η 6 -2-OH-C 6 H 4 CHO)]PF 6 (for 5) (Cp* = η 5 -C 5 Me 5 ). The four complexes were isolated as air and moisture insensitive solids in yields > 80 %. They were characterized using several analytical techniques such as CHN analyses, ESI mass, FT-IR, UV-vis and NMR spectroscopy, including single crystal X-ray diffraction analysis. The crystal structure of 3 reveals that the four-coordinate copper atom adopts a square planar geometry with two nitrogen and two oxygen atoms as donors occupying cis positions. An electrochemical study utilizing cyclic voltammetry showed for each compound a reversible redox process ascribed to the Fe(II)/Fe(III) couple of the appended donor ferrocene. The largest anodic potentials were measured for the two Co(II) species. The second-order NLO responses of the push-pull chromophores 2-5 have been determined by harmonic light scattering measurements in N,Ndimethylformamide solutions at 1.91 μm incident wavelength, and rather high, non-resonant quadratic hyperpolarisability β values ranging from 140-280 x 10 -30 esu were determined.

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Section: Introductionmentioning

confidence: 99%

Transition metal(II) complexes featuring push-pull dianionic Schiff base ligands: synthesis, crystal structure, electrochemical, and NLO studies

Celedón

Roisnel

Carrillo

et al. 2020

Journal of Coordination Chemistry

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“…The key building block [( S p )‐ 1 ] for the synthesis of ligand ( S p , S p )‐ 3 is available from Kagan's ferrocene acetal9 in four steps, as described previously 10. Reaction of the ( S p )‐isomer of this O‐silyl‐protected 2‐hydroxyferrocene carbaldehyde with half an equivalent of ethylenediamine in ethanol gave rise to the bisprotected ligand precursor ( S p , S p )‐ 2 in almost quantitative yield.…”

Section: Resultsmentioning

confidence: 99%

Salen Ligands Revisited: Synthesis and Application of a Planar Chiral “Ferro‐Salen” Ligand

et al. 2010

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Condensation of the O‐protected planar chiral hydroxyferrocene carbaldehyde (Sp)‐1 with ethylenediamine, followed by deprotection gave rise to the “ferro‐salen” ligand (Sp,Sp)‐3 in good yield. This scaffold was used for the preparation of a series of metal complexes [(Sp,Sp)‐4/5/6], which were subsequently applied for the Lewis acid catalyzed asymmetric trimethylsilylcyanation of benzaldehyde.

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“…Although a lot of specific problems associated with this attractive, but challenging development are not solved yet (especially with regard to the specific attachment of important catalysis controlling substituents 10-12 ), we may have opened a door to interesting future catalytic developments by our first simple examples of optically active bis("ferrocene-salicylminato")MX 2type complexes (and derivatives thereof). 8 Some of the synthetic and structural chemistry of these first new examples will be described in this article, followed by a brief account of first catalytic experiments.…”

Section: Methodsmentioning

confidence: 99%

“…The Zr complex had been described and its molecular structure depicted in a preliminary communication. 8 Therefore, we will only depict the analogous structure of the corresponding hafnium complex (p-S,p-S,K)-7a in this account (see Fig. 6).…”

Section: Methodsmentioning

confidence: 99%

“…6,7 We seem to have done this for the first time by introducing a planar chiral variant of the salicylaldiminato systems, namely the "ferrocene-saliminato" system. 8,9 Attaching two like enan-Organisch-Chemisches Institut, Universität Münster, Corrensstraße 40, D-41849, Münster, Germany. E-mail: erker@uni-muenster.de;Fax: +49-251-8336503 † Electronic supplementary information (ESI) available: Details of NMR spectroscopic characterizations, kinetic NMR experiments, and polymerisation reactions.…”

Section: Introductionmentioning

confidence: 99%

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Bis(“ferrocene-saliminato”) group 4 metal complexes: synthesis, structural features and use in homogenous Ziegler–Natta polymerization catalysis

et al. 2009

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Reaction of the (p-S) enantiomers of the N-aryl-substituted planar chiral alpha-hydroxy-ferrocene carbaldimines [(p-S)- (aryl=2,6-diisopropylphenyl (), -C6F5 ()] with LDA gave the corresponding lithiated "ferrocene-saliminato" systems (p-S)- and (p-S)-, respectively. Both were characterized by X-ray diffraction. In the crystal, compound (p-S)- features an associated cyclotrimeric structure with a six-membered alternating Li3O3 core while (p-S)- shows a cyclotetrameric structure around a central cubic Li4O4 core unit. The reagent (p-S)- was treated with the group 4 metal tetrahalides to yield the bis(ferrocene-saliminato)MCl2 complexes (Ti), (Zr), and (Hf). In the crystal the latter feature single diastereomeric octahedral (p-S,p-S,Lambda)- (Zr) and (p-S,p-S,Lambda)- (Hf) structures, whereas the titanium analogue shows both the (p-S,p-S,Lambda)- and the (p-S,p-S,Delta)- diastereoisomers in the crystal. Upon dissolving, we observe a rapid Delta- to Lambda- isomerization to occur. The latter is the only isomer observed in solution under thermodynamic control. In contrast, the pure Lambda- and Lambda- isomers equilibrate in solution with a second isomer to a ca. 1:1 mixture. Treatment of (p-S)- (aryl=C6F5) with TiCl4 or ZrCl4 gave the analogous octahedral complexes and , respectively, as single diastereoisomers. Treatment of the neutral ferrocene-salimines (p-S)- with ZrCl4 or HfCl4 gave the respective N-aryl-substituted zwitterionic (ferrocene-salimine)2MCl4 complexes (: Zr, 2,6-diisopropylphenyl; : Hf, 2,6-diisopropylphenyl; : Zr, mesityl; : Zr, C6F5), that contain the zwitterionic iminium-tautomers O-bonded to the metal. Activation of a variety of the complexes and with methylalumoxane gave homogeneous ethylene polymerization catalysts that exhibit low to moderate catalyst activities in the 20 degrees C to 125 degrees C temperature range.

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Mastering the Third Dimension of Salicylaldimine‐Type Ligand Systems: Development of a Convenient Route to Bis(“ferrocene–saliminato”)zirconium Chemistry

Cited by 27 publications

References 30 publications

Transition metal(II) complexes featuring push-pull dianionic Schiff base ligands: synthesis, crystal structure, electrochemical, and NLO studies

Transition metal(II) complexes featuring push-pull dianionic Schiff base ligands: synthesis, crystal structure, electrochemical, and NLO studies

Salen Ligands Revisited: Synthesis and Application of a Planar Chiral “Ferro‐Salen” Ligand

Bis(“ferrocene-saliminato”) group 4 metal complexes: synthesis, structural features and use in homogenous Ziegler–Natta polymerization catalysis

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