Transition‐Metal‐Based Linear Chain Compounds

Majumdar, Moumita; Bera, Jitendra K.

doi:10.1002/9780470527085.ch5

Cited by 14 publications

(8 citation statements)

References 136 publications

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“…The current record spin value is S = 11 for a mixed-valent hexairon complex with an octahedral metal topology . Similar features are encountered in the so-called extended metal atom chains (EMACs), which have attracted attention as molecular analogues of macroscopic wires and benchmark systems for understanding metal–metal interactions. − EMACs consist of three or more metal centers forming a linear array supported by three or four deprotonated oligo-α-pyridylamine (or related) ligands, most often arranged in a helical fashion. − Their molecular wire-like structure has either rigorous or idealized axial symmetry and makes high-spin EMACs potential SMMs. In fact, the tri- and pentachromium(II) compounds [Cr 3 (dpa) 4 Cl 2 ]·CH 2 Cl 2 ( 1a ·CH 2 Cl 2 ) and [Cr 5 (tpda) 4 Cl 2 ]·4CHCl 3 ·2Et 2 O ( 2a ·4CHCl 3 ·2Et 2 O) have a well-isolated S = 2 state, display an easy-axis anisotropy of similar magnitude, and behave as SMMs with energy barriers of 10.6(6) and 8.6(5) K, respectively [Hdpa = dipyridin-2-yl-amine; H 2 tpda = N 2 , N 6 -di(pyridin-2-yl)pyridine-2,6-diamine; see Scheme ].…”

Section: Introductionmentioning

confidence: 96%

“… 25 Similar features are encountered in the so-called extended metal atom chains (EMACs), which have attracted attention as molecular analogues of macroscopic wires and benchmark systems for understanding metal–metal interactions. 26 − 29 EMACs consist of three or more metal centers forming a linear array supported by three or four deprotonated oligo-α-pyridylamine (or related) ligands, most often arranged in a helical fashion. 30 − 32 Their molecular wire-like structure has either rigorous or idealized axial symmetry and makes high-spin EMACs potential SMMs.…”

Section: Introductionmentioning

confidence: 99%

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The Origin of Magnetic Anisotropy and Single-Molecule Magnet Behavior in Chromium(II)-Based Extended Metal Atom Chains

et al. 2020

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S2 1. Synthesis General. Unless otherwise noted, reagents and solvents were of commercial origin and used without further purification. Naphthalene was resublimed and NaSCN was recrystallized from acetone before use. Dichloromethane and diethyl ether for the synthesis of 1a•Et2O were purified using an Inert Technologies solvent purification system. For the synthesis of 2a4CHCl32Et2O and 2b anhydrous dichloromethane (Sigma-Aldrich) was directly used, while chloroform was washed with water, stirred over CaCl2 overnight and distilled under N2; diethyl ether was pre-dried over CaCl2 overnight and distilled from its sodium benzophenone ketyl solution under N2; n-hexane was dried over 4A molecular sieves; all these solvents were degassed by three freeze-pump-thaw cycles. 1 The H2tpda ligand was prepared as described elsewhere, 2,3 recrystallized from boiling methanol or 2-propanol and checked by 1 H NMR spectroscopy and melting point measurement. All reactions involving chromium(II) complexes were carried out under Ar or N2 atmosphere using Schlenk techniques or glovebox methods. Elemental analysis was carried out by Microlab Kolbe (Oberhausen, Germany, 1a•Et2O) or on a Carlo Erba EA1110 CHNS-O automatic analyzer (2a4CHCl32Et2O and 2b). The IR spectra were measured on a Nicolet 6700 FT-IR spectrometer using a Smart iTR accessory between 600 and 4000 cm-1 with 4 cm-1 resolution (1a•Et2O) or on a JASCO 4700 FT-IR spectrometer between 400 and 4000 cm-1 with 2 cm −1 resolution (2a4CHCl32Et2O and 2b). Electrospray Ionization Mass Spectrometry (ESI-MS) was performed on an Agilent Technologies 6310A Ion Trap LC-MS(n) spectrometer. Synthesis of [Cr3(dpa)4Cl2]•Et2O (1a•Et2O). Complex 1a was prepared following a literature procedure 4,5 and isolated as the monodiethylether solvate 6,7 by layering a dichloromethane solution with diethyl ether, yielding a crop of dark green crystals in 60% yield after a week of diffusion. Anal. Calcd for

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Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

The Origin of Magnetic Anisotropy and Single-Molecule Magnet Behavior in Chromium(II)-Based Extended Metal Atom Chains

et al. 2020

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“…To a solution of 5•1.5CH 2 Cl 2 (20.4 mg, 0.0065 mmol) in CH 2 Cl 2 (3 mL) was added KBr (6.0 mg, 0.050 mmol). The mixture was stirred at room temperature for 16 h. Then, the solution was filtered by membrane [Pd 2 I 2 (rac-dpmppm)(rac-Binac)] 2 (OTf) 4 (7). To a solution of 5• 1.5CH 2 Cl 2 (19.5 mg, 0.0062 mmol) in CH 2 Cl 2 (3 mL) was added KI (5.0 mg, 0.030 mmol).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…One dimensionally extended metal atom chains (EMACs) wrapped by insulating organic ligands are actual nanoscale miniatures of electric cables and, hence, can be recognized as important single molecules to study 1D signal transductions including quantum electron transporting phenomena and as versatile building blocks to develop molecular based electronic devices. − Nevertheless, successfully synthesized examples have still been very limited to those utilizing linearly designed template ligands, − which involves Ni 9 and Ni 11 chains supported by polypyridyl- and polynaphthyridylamide ligands, − and Pd 10 chains sandwiched by two β-carotenes, as the longest structurally characterized EMACs . We have also developed low-valent metal atom chains of Pt and Pd atoms by using methylene-bridged linear triphosphine, bis(diphenylphosphinomethyl)phenylphosphine (dpmp), − tetraphosphines, meso - and rac -bis[(diphenylphosphinomethyl)phenylphosphino]methane (dpmppm), − and a PCP- and PNP-bridged tetraphosphine, rac -bis[(diphenylphosphinomethyl)phenylphosphino]phenylamine (dpmppan) .…”

Section: Introductionmentioning

confidence: 99%

Chiral Octapalladium Chains Supported by Enantiopure P-Stereogenic Linear Tetraphosphines, (R,R)- and (S,S)-Ph₂PCH₂P(Ph)CH₂P(Ph)CH₂PPh₂

et al. 2021

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Binuclear Pd(II) and Pt(II) complexes supported by rac-dpmppm (bis[(diphenylphosphinomethyl)phenylphosphino]methane) in a triply-bridged Z-form, [M2Cl4(rac-dpmppm)] (M = Pd (3a), Pt (3b)), readily reacted with 2,6-xylyl isocyanide (XylNC) in the presence of NH4PF6 to afford [M2Cl2(rac-dpmppm)(XylNC)2](PF6)2 (M = Pd (4a), Pt (4b)), in which each metal center accommodates one isocyanide ligand at the trans position to the inner P atom of dpmppm. Similarly, treatment of 3a and 3b with axially chiral (R/S)-1,1′-binaphthyl-2,2′-bisisocyanide (rac-Binac) in the presence of NH4OTf gave cyclic tetranuclear complexes, [{M2Cl2(rac-dpmppm)(rac-Binac)}2](OTf)4 (M = Pd (5), Pt (8)), where two {M2Cl2(rac-dpmppm)}2+ fragments are connected by two rac-Binac ligands through chirality sorting of (R*,R*)-dpmppm and (R*)-Binac. Complex 5 could be transformed into the halide exchanged tetranuclear complexes, [{Pd2X2(rac-dpmppm)(rac-Binac)}2](OTf)4 (X = Br (6), I (7)), to show that the rectangular arrangement of four Pd(II) ions is elongated by repulsive interaction between halide ligands. By using (R)- and (S)-Binac, enantiopure Pd4 complexes, [{Pd2Cl2((R*,R*)-dpmppm)((R*)-Binac)}2](OTf)4 (5 RR/R and 5 SS/S ), were successfully isolated as pure crystalline forms, from which enantiopure (R,R)- and (S,S)-dpmppm were obtained by treatment with NaCN aqueous solution. Namely, optical resolution of rac-dpmppm was established through the tetranuclear Pd complexes, which is the first example for methylene-bridged polyphosphines, R2P(CH2PR) n CH2PR2 (n > 0). Furthermore, chiral octapalladium chains, [Pd8((R*,R*)-dpmppm)4(NCCH3)2](BF4)4 (2 RR and 2 SS ), were synthesized by reacting enantiopure P-chiral dpmppm with [Pd2(CH3CN)6](BF4)2 and [Pd2(dba)3]·C6H6 and were characterized by spectroscopic and X-ray crystallographic analyses, to determine the absolute configurational structures. The Pd8 chains are the longest enantiopure chiral single-metal-atom chains structurally characterized, thus far, and the electronic structures were examined on the basis of DFT calculations of 2 RR .

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“…These terms refer to polynuclear paddlewheel complexes with three or more linearly-arranged arranged metal atoms bridged by four equatorial ligands, typically oligopyridylamines. These compounds, often containing metal-metal bonds, have been extensively studied since the late 1990s because of their fascinating magnetic and electronic properties [17][18][19]. Much less studied, however, is the use of such complexes to build extended structures, with only few one-dimensional (1D) and two-dimensional (2D) CPs based on [Co3(dpa)4] 2+ [20][21][22] and [Ni3(dpa)4] 2+ [23,24] (dpa = the anion of 2,2′−dipyridylamine) to be found in the literature.…”

Section: Introductionmentioning

confidence: 99%

Enantiopure Chiral Coordination Polymers Based on Polynuclear Paddlewheel Helices and Arsenyl Tartrate

et al. 2018

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Herein, we report the preparation of chiral, one-dimensional coordination polymers based on trinuclear paddlewheel helices [M 3 (dpa) 4 ] 2+ (M = Co(II) and Ni(II); dpa = the anion of 2,2 -dipyridylamine). Enantiomeric resolution of a racemic mixture of [M 3 (dpa) 4 ] 2+ complexes was achieved by chiral recognition of the respective enantiomer by [∆-As 2 (tartrate) 2 ] 2− or [Λ-As 2 (tartrate) 2 ] 2− in N,N-dimethylformamide (DMF), affording crystalline coordination polymers formed from [(∆-Co 3 (dpa) 4 )(Λ-As 2 (tartrate) 2 )]·3DMF (∆-1), [(Λ-Co 3 (dpa) 4 )(∆-As 2 (tartrate) 2 )]·3DMF (Λ-1), [(∆-Ni 3 (dpa) 4 )(Λ-As 2 (tartrate) 2 )]·(4 − n)DMF·nEt 2 O (∆-2) or [(Λ-Ni 3 (dpa) 4 )(∆-As 2 (tartrate) 2 )]·(4 − n)DMF·nEt 2 O (Λ-2) repeating units. UV-visible circular dichroism spectra of the complexes in DMF solutions demonstrate the efficient isolation of optically active species. The helicoidal [M 3 (dpa) 4 ] 2+ units that were obtained display high stability towards racemization as shown by the absence of an evolution of the dichroic signals after several days at room temperature and only a small decrease of the signal after 3 h at 80 • C.

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Transition‐Metal‐Based Linear Chain Compounds

Cited by 14 publications

References 136 publications

The Origin of Magnetic Anisotropy and Single-Molecule Magnet Behavior in Chromium(II)-Based Extended Metal Atom Chains

The Origin of Magnetic Anisotropy and Single-Molecule Magnet Behavior in Chromium(II)-Based Extended Metal Atom Chains

Chiral Octapalladium Chains Supported by Enantiopure P-Stereogenic Linear Tetraphosphines, (R,R)- and (S,S)-Ph₂PCH₂P(Ph)CH₂P(Ph)CH₂PPh₂

Enantiopure Chiral Coordination Polymers Based on Polynuclear Paddlewheel Helices and Arsenyl Tartrate

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Transition‐Metal‐Based Linear Chain Compounds

Cited by 14 publications

References 136 publications

The Origin of Magnetic Anisotropy and Single-Molecule Magnet Behavior in Chromium(II)-Based Extended Metal Atom Chains

The Origin of Magnetic Anisotropy and Single-Molecule Magnet Behavior in Chromium(II)-Based Extended Metal Atom Chains

Chiral Octapalladium Chains Supported by Enantiopure P-Stereogenic Linear Tetraphosphines, (R,R)- and (S,S)-Ph2PCH2P(Ph)CH2P(Ph)CH2PPh2

Enantiopure Chiral Coordination Polymers Based on Polynuclear Paddlewheel Helices and Arsenyl Tartrate

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Chiral Octapalladium Chains Supported by Enantiopure P-Stereogenic Linear Tetraphosphines, (R,R)- and (S,S)-Ph₂PCH₂P(Ph)CH₂P(Ph)CH₂PPh₂