Monomeric, trimeric, and tetrameric transition metal complexes (Mn, Fe, Co) containing <i>N</i>,<i>N</i>-bis(2-pyridylmethyl)-2-aminoethanol/-ate: preparation, crystal structure, molecular magnetism and oxidation catalysis

Shin, Jong Won,Rowthu, Sankara Rao,Hyun, Min Young,Song, Young Joo,Kim, Cheal,Kim, Bong Gon,Min, Kil Sik Royal Society of Chemistry 2011 Dalton transactions Vol.40 No.21

<P>The reaction of <I>N</I>,<I>N</I>–bis(2-pyridylmethyl)-2-aminoethanol (bpaeOH), NaSCN/NaN<SUB>3</SUB>, and metal (M) ions [M = Mn(<SMALL>II</SMALL>), Fe(<SMALL>II</SMALL>/<SMALL>III</SMALL>), Co(<SMALL>II</SMALL>)] in MeOH, leads to the isolation of a series of monomeric, trimeric, and tetrameric metal complexes, namely [Mn(bpaeOH)(NCS)<SUB>2</SUB>] (1), [Mn(bpaeO)(N<SUB>3</SUB>)<SUB>2</SUB>] (2), [Fe(bpaeOH)(NCS)<SUB>2</SUB>] (3), [Fe<SUB>4</SUB>(bpaeO)<SUB>2</SUB>(CH<SUB>3</SUB>O)<SUB>2</SUB>(N<SUB>3</SUB>)<SUB>8</SUB>] (4), [Co(bpaeOH)(NCS)<SUB>2</SUB>] (5), and [Co<SUB>3</SUB>(bpaeO)<SUB>2</SUB>(NO<SUB>3</SUB>)(N<SUB>3</SUB>)<SUB>4</SUB>](NO<SUB>3</SUB>) (6). These compounds have been investigated by single crystal X-ray diffractometry and magnetochemistry. In complex 1 the Mn(<SMALL>II</SMALL>) is bonded to one bpaeOH and two thiocyanate ions, while in complex 2 it is coordinated to a deprotonated bpaeO<SUP>−</SUP> and two azide ions. The oxidation states of manganese ions are 2+ for 1 and 3+ for 2, respectively, indicating that the different oxidation states depend on the type of binding anions. The structures of monomeric iron(<SMALL>II</SMALL>) and cobalt(<SMALL>II</SMALL>) complexes 3 and 5 with two thiocyanate ions are isomorphous to that of 1. Compounds 1, 2, 3, and 5 exhibit high-spin states in the temperature range 5 to 300 K. 4 contains two different iron(<SMALL>III</SMALL>) ions in an asymmetric unit, one is coordinated to a deprotonated bpaeO<SUP>−</SUP>, an azide ion, and a methoxy group, and the other is bonded to three azide ions and two oxygens from bpaeO<SUP>−</SUP> and a methoxy group. Two independent iron(<SMALL>III</SMALL>) ions in 4 form a tetranuclear complex by symmetry. 4 displays both ferromagnetic and antiferromagnetic couplings (<I>J</I> = 9.8 and −14.3 cm<SUP>−1</SUP>) between the iron(<SMALL>III</SMALL>) ions. 6 is a mixed-valence trinuclear cobalt complex, which is formulated as Co<SUP>III</SUP>(<I>S</I> = 0)–Co<SUP>II</SUP>(<I>S</I> = 3/2)–Co<SUP>III</SUP>(<I>S</I> = 0). The effective magnetic moment at room temperature corresponds to the high-spin cobalt(<SMALL>II</SMALL>) ion (∼4.27 <I>μ</I><SUB>B</SUB>). Interestingly, 6 showed efficient catalytic activities toward various olefins and alcohols with modest to excellent yields, and it has been proposed that a high-valent Co<SUP>V</SUP>–oxo species might be responsible for oxygen atom transfer in the olefin epoxidation and alcohol oxidation reactions.</P> <P>Graphic Abstract</P><P>Mn, Fe and Co complexes with interesting properties are reported. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c1dt10028a'> </P>

Syntheses, structures and magnetic properties of dinuclear oxo-bridged iron(III) complexes

Shin, Jong Won,Rowthu, Sankara Rao,Lee, Ju Eun,Lee, Hong In,Min, Kil Sik Elsevier 2012 Polyhedron Vol.33 No.1

<P><B>Graphical abstract</B></P><P>We have prepared three novel iron(III) complexes which show oxo-bridged dinuclear iron(III) structures. Complexes <B>1</B> and <B>3</B> display offset face-to-face π–π interactions between the dinuclear units, while <B>2</B> shows hydrogen bonding interactions via the hydroxyl group. The magnetic data of all the complexes indicate that very strong antiferromagnetic couplings occur via the oxo bridge within the iron(III) dimer and weak antiferromagnetic interactions exist between the dimers.</P><ce:figure id='f0040'></ce:figure> <P><B>Abstract</B></P><P>The reaction of tris(2-pyridylmethyl)amine (TPyA)/<I>N</I>,<I>N</I>-bis(2-pyridylmethyl)-2-aminoethanol (bpaeOH), H<SUB>2</SUB>DHBN/Na<SUB>2</SUB>C<SUB>2</SUB>O<SUB>4</SUB>/NaN<SUB>3</SUB> and Fe(II/III) ions in MeOH leads to the isolation of three iron(III) dimeric complexes, namely [(TPyA)(DHBN)Fe<SUP>III</SUP>OFe<SUP>III</SUP>(TPyA)(DHBN)]·2H<SUB>2</SUB>O (<B>1</B>), [(bpaeOH)(C<SUB>2</SUB>O<SUB>4</SUB>)Fe<SUP>III</SUP>OFe<SUP>III</SUP>(C<SUB>2</SUB>O<SUB>4</SUB>)(bpaeOH)]·2H<SUB>2</SUB>O (<B>2</B>) and [(TPyA)(N<SUB>3</SUB>)Fe<SUP>III</SUP>OFe<SUP>III</SUP>(N<SUB>3</SUB>)(TPyA)](ClO<SUB>4</SUB>)<SUB>2</SUB> (<B>3</B>) (H<SUB>2</SUB>DHBN=3,4-dihydroxybenzonitrile). These complexes have been investigated by single crystal X-ray diffractometry and magnetochemistry. Complexes <B>1</B>–<B>3</B> show dimeric structures with a bridging oxo (O<SUP>2−</SUP>) ion, and all the iron(III) ions have a distorted octahedral geometry. Complexes <B>1</B> and <B>3</B> have offset face-to-face π–π interactions between the dimers and possess a supramolecular structure, while <B>2</B> has O–H···O hydrogen bonding interactions between the dimers, which gives rise to a 1-D chain structure. These (<I>μ</I>-oxo)diiron(III) complexes exhibit antiferromagnetic interactions [<B>1</B>: <I>g</I>=2.0, <I>J</I>/<I>k</I><SUB>B</SUB>=−112K (−78cm<SUP>−1</SUP>), <I>θ</I>=−0.29K, <I>ρ</I>=0.035; <B>2</B>: <I>g</I>=2.0, <I>J</I>/<I>k</I><SUB>B</SUB>=−141K (−98cm<SUP>−1</SUP>), <I>θ</I>=−0.3K, <I>ρ</I>=0.01; <B>3</B>: <I>g</I>=2.0, <I>J</I>/<I>k</I><SUB>B</SUB>=−130K (−90cm<SUP>−1</SUP>), <I>θ</I>=−0.5K, <I>ρ</I>=0.009]. These indicate that very strong antiferromagnetic interactions occur via the oxo bridge within the iron(III) dimer and weak antiferromagnetic interactions exist between the dimers.</P>

A zigzag tetranuclear iron(<small>III</small>) complex, [Fe₄(bpaeO)₂(CH₃O)₂(N₃)₈] coexisting both ferromagnetic and antiferromagnetic couplings (bpaeOH = <i>N</i>,<i>N</i>-bis(2-pyridylmet

Shin, Jong Won,Rowthu, Sankara Rao,Kim, Bong Gon,Min, Kil Sik Royal Society of Chemistry 2010 Dalton Transactions Vol.39 No.11

<P>A zigzag tetranuclear [Fe<SUB>4</SUB>(bpaeO)<SUB>2</SUB>(CH<SUB>3</SUB>O)<SUB>2</SUB>(N<SUB>3</SUB>)<SUB>8</SUB>] possesses two different high-spin ferric sites and both ferromagnetic and antiferromagnetic interactions exist within the iron(<SMALL>III</SMALL>) ions.</P> <P>Graphic Abstract</P><P>A zigzag tetranuclear [Fe<SUB>4</SUB>(bpaeO)<SUB>2</SUB>(CH<SUB>3</SUB>O)<SUB>2</SUB>(N<SUB>3</SUB>)<SUB>8</SUB>] possesses two different high-spin ferric sites and both ferromagnetic and antiferromagnetic interactions exist within the iron(<SMALL>III</SMALL>) ions. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c000412j'> </P>

Synthesis, Crystal structure, and Magnetic Properties of Dinuclear Iron(III) Complexes with Methoxo Bridges

Shin, Jong-Won,Han, Jeong-Hyeong,Rowthu, Sankara Rao,Kim, Bong-Gon,Min, Kil-Sik Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.12

The reaction of stoichiometric amount of $FeCl_2{\cdot}4H_2O$, (2-pyridylmethyl, 3-pyridylmethyl)amine (2,3-pyma) and sodium azide/sodium thiocyanate in methanol under aerobic conditions affords the dinuclear Fe(III) complexes, [(2,3-pyma) $(N_3)_2Fe({\mu}-OCH_3)_2Fe(N_3)_2$(2,3-pyma)]${\cdot}CH_3OH$ (1) and [(2,3-pyma)$(NCS)_2Fe({\mu}-OCH_3)_2Fe(NCS)_2$(2,3-pyma)] (2) in good yield. Two bis-methoxy-bridged diiron(III) complexes are isolated and characterized. The coordination geometries around iron(III) ions in 1 and 2 are the same tetragonally distorted octahedron. The iron(III) ions are coordinated by two nitrogens of a 2,3-pyma, two nitrogens of two azide/thiocyanate ions, and two oxygens of two methoxy groups. Both compounds are isomorphous. The structures of 1 and 2 display the C-$H{\cdots}\pi$ and/or $\pi-\pi$ stacking interactions as well as hydrogen bonding interactions, respectively. Compounds 1 and 2 show significant antiferromagnetic couplings through the bridged methoxy groups between the iron(III) ions in the temperature range from 5 to 300 K ($H=-2JS_1{\cdot}S_2$, J=-19.1 and $-13.9\;cm^{-1}$ for 1 and 2).

Synthesis and characterization of enantiopure copper(<small>II</small>) complexes using chiral bidentate ligands

Min, Kil Sik,Park, A Hyun,Shin, Jong Won,Rowthu, Sankara Rao,Kim, Seog K.,Ryoo, Jae Jeong Royal Society of Chemistry 2010 Dalton transactions Vol.39 No.37

<P>Chiral copper(<SMALL>II</SMALL>) complexes of the types [Cu<SUP>II</SUP>(<I>R</I>/<I>S</I>-ppme)<SUB>3</SUB>](ClO<SUB>4</SUB>)<SUB>2</SUB> and [Cu<SUP>II</SUP>(<I>R</I>/<I>S</I>-ppme)<SUB>2</SUB>(SO<SUB>4</SUB>)] have been synthesized by reactions of Cu(ClO<SUB>4</SUB>)<SUB>2</SUB>·6H<SUB>2</SUB>O and CuSO<SUB>4</SUB>·5H<SUB>2</SUB>O with <I>R</I>/<I>S</I>-ppme in methanol under aerobic conditions (<I>R</I>/<I>S</I>-ppme = (<I>R</I>/<I>S</I>)-(±)-1-phenyl-<I>N</I>-(pyridine-2-ylmethylene)ethanamine). All complexes were isolated and characterized by X-ray crystallography and circular dichroism (CD): (Λ)-[Cu<SUP>II</SUP>(<I>R</I>-ppme)<SUB>3</SUB>](ClO<SUB>4</SUB>)<SUB>2</SUB> (<B>1</B>), (Δ)-[Cu(<I>S</I>-ppme)<SUB>3</SUB>](ClO<SUB>4</SUB>)<SUB>2</SUB>·H<SUB>2</SUB>O (<B>2</B>), (Δ)-[Cu<SUP>II</SUP>(<I>R</I>-ppme)<SUB>2</SUB>(SO<SUB>4</SUB>)]·4CH<SUB>3</SUB>OH (<B>3</B>), and (Λ)-[Cu<SUP>II</SUP>(<I>S</I>-ppme)<SUB>2</SUB>(SO<SUB>4</SUB>)]·4CH<SUB>3</SUB>OH (<B>4</B>). <B>1</B> and <B>2</B> with ClO<SUB>4</SUB><SUP>−</SUP> anions are formed as tris(<I>R</I>/<I>S</I>-ppme) copper(<SMALL>II</SMALL>) complexes, while <B>3</B> and <B>4</B> with SO<SUB>4</SUB><SUP>2−</SUP> are formed as bis(<I>R</I>/<I>S</I>-ppme) copper(<SMALL>II</SMALL>) complexes. The structures of <B>1</B> with <I>R</I>-ppmes and <B>4</B> with <I>S</I>-ppmes show the same absolute configurations (Λ). In contrast, <B>2</B> with <I>S</I>-ppmes and <B>3</B> with <I>R</I>-ppmes exhibit Δ configurations. In the electron paramagnetic resonance (EPR) spectra of <B>1</B> and <B>3</B>, both compounds demonstrate <I>z</I>-axis elongated structures. The CD spectra of <B>1</B> and <B>2</B> show Cotton effects in an enantiomeric pattern; those of <B>3</B> and <B>4</B> also display the same effects.</P> <P>Graphic Abstract</P><P>Complexes <B>1</B> and <B>2</B> are coordinated by three <I>R</I>/<I>S</I>-ppme ligands, in which they form distorted octahedral structures. The structures of <B>1</B> and <B>2</B> display Λ and Δ configurations, respectively. The CD spectra of <B>1</B> and <B>2</B> exhibit Cotton effects in an enantiomeric pattern. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0dt00380h'> </P>

Synthesis, Crystal structure, and Magnetic Properties of Dinuclear Iron(Ⅲ ) Complexes with Methoxo Bridges

Jong Won Shin,Jeong Hyeong Han,Sankara Rao Rowthu,Bong Gon Kim,Kil Sik Min 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.12

The reaction of stoichiometric amount of FeCl2·4H2O, (2-pyridylmethyl, 3-pyridylmethyl)amine (2,3-pyma) and sodium azide/sodium thiocyanate in methanol under aerobic conditions affords the dinuclear Fe(III) complexes, [(2,3-pyma) (N3)2Fe(μ-OCH3)2Fe(N3)2(2,3-pyma)]·CH3OH (1) and [(2,3-pyma)(NCS)2Fe(μ-OCH3)2Fe(NCS)2(2,3-pyma)] (2) in good yield. Two bis-methoxy-bridged diiron(III) complexes are isolated and characterized. The coordination geometries around iron(III) ions in 1 and 2 are the same tetragonally distorted octahedron. The iron(III) ions are coordinated by two nitrogens of a 2,3-pyma, two nitrogens of two azide/thiocyanate ions, and two oxygens of two methoxy groups. Both compounds are isomorphous. The structures of 1 and 2 display the C-H···π and/or π-π stacking interactions as well as hydrogen bonding interactions, respectively. Compounds 1 and 2 show significant antiferromagnetic couplings through the bridged methoxy groups between the iron(III) ions in the temperature range from 5 to 300 K (H = ‒2JS1·S2, J = ‒19.1 and ‒13.9 cm‒1 for 1 and 2).