Synthesis, structure, and solution NMR studies of cyanide-copper(II) and cyanide-bridged iron(III)-copper(II) complexes

Daniele M. Corsi, Narasimha N. Murthy, Victor G. Young, Kenneth D. Karlin

Research output: Contribution to journalArticle

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Abstract

A range of small molecules, such as cyanide, are known to bind and/or inhibit the active site of the heme-copper oxidase enzymes. As such, model studies are aimed at elucidating ligand binding modes and their subsequent impact on spectroscopic properties of derived complexes. We describe here the isolation and characterization of two compounds containing the Fe-CN-Cu moiety, [(py)(F8-TPP)FeIII-CN-CuII(TMPA)]2+ (5) and [(F8-TPP)-FeIII-(CN)2-{Cu II(TMPA)}2]3+ (6) [py = pyridine, TMPA = tris(2-pyridylmethyl)amine, and (F8-TPP) = tetrakis-(2,6-difluorophenyl)porphyrinate(2-)]. [CuII(TMPA)(CH3CN)](ClO4)2 and [(py)(F8-TPP)FeIII(CN)] (3) react to yield 5, while 6 is formed by combination of [CuII(TMPA)(CN)]PF6 (2-(PF6)) and [(F8-TPP)FeIII(PF6)] (4). Complex 2-(PF6) crystallizes in the orthorhombic space group Iba2 with a = 17.2269(5) Å, b = 17.3143(4) Å, and c = 14.4971(4) Å, Z = 8, complex (5-(Sb/P)F6)1.5(ClO4)0.5 was obtained in the orthorhombic space group P222 with a = 17.9541(2) Å, b = 20.5359(1) Å, and c = 21.2023(2) Å, Z = 4, and 6-(PF6)3 crystallized in the monoclinic space group P21/c with a = 15.318(4) Å, b = 33.921(2) Å, and c = 19.649(6) Å, β = 109.69(2)°, and Z = 4. Compound 5 possesses a low-spin iron(III) center, bridged via cyanide to copper. The iron-cyanide vector deviates slightly from linearity (174.6(5)°). The copper(II) ion is five-coordinated by the TMPA N-donor atoms and the cyanide carbon atom. The Cu(TMPA) moiety is bent with an angle of 163.8(5)° around the cyanide-copper vector. Compound 6 possesses a low-spin iron(III) atom axially coordinated by two cyanide ligands capped on either side by trigonally coordinated [Cu(TMPA)] moieties. The [Cu(1)(TMPA)] unit is twisted somewhat (∠Cu1-N≡C = 168°), whereas the [Cu(2)(TMPA)] unit is coordinated in a nearly linear fashion with respect to the cyanide-iron vector (∠Cu2-N≡C4 = 175°). 1H and 2H NMR spectroscopy on 5 and 6 confirmed the low-spin nature of these iron complexes (pyrrole resonance found at -11.1 and -8 ppm, respectively). The NMR data as well as observed solution magnetic moment (μB = 2.7 for 5; μB = 3.4 for 6) suggest ferromagnetic coupling between the paramagnetic metal ions. This gives rise to an enhancement of the electronic relaxation rate for Cu(II) in both 5 and 6 allowing for the observation of the sharp and downfield shifted TMPA ligand proton signals.

Original languageEnglish (US)
Pages (from-to)848-858
Number of pages11
JournalInorganic Chemistry
Volume38
Issue number5
StatePublished - Dec 1 1999

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iron cyanides
Cyanides
cyanides
Copper
Iron
Nuclear magnetic resonance
copper
nuclear magnetic resonance
synthesis
iron
ligands
Ligands
Atoms
atoms
oxidase
pyrroles
linearity
Pyrroles
enzymes
isolation

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Synthesis, structure, and solution NMR studies of cyanide-copper(II) and cyanide-bridged iron(III)-copper(II) complexes. / Corsi, Daniele M.; Murthy, Narasimha N.; Young, Victor G.; Karlin, Kenneth D.

In: Inorganic Chemistry, Vol. 38, No. 5, 01.12.1999, p. 848-858.

Research output: Contribution to journalArticle

Corsi, Daniele M. ; Murthy, Narasimha N. ; Young, Victor G. ; Karlin, Kenneth D. / Synthesis, structure, and solution NMR studies of cyanide-copper(II) and cyanide-bridged iron(III)-copper(II) complexes. In: Inorganic Chemistry. 1999 ; Vol. 38, No. 5. pp. 848-858.
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title = "Synthesis, structure, and solution NMR studies of cyanide-copper(II) and cyanide-bridged iron(III)-copper(II) complexes",
abstract = "A range of small molecules, such as cyanide, are known to bind and/or inhibit the active site of the heme-copper oxidase enzymes. As such, model studies are aimed at elucidating ligand binding modes and their subsequent impact on spectroscopic properties of derived complexes. We describe here the isolation and characterization of two compounds containing the Fe-CN-Cu moiety, [(py)(F8-TPP)FeIII-CN-CuII(TMPA)]2+ (5) and [(F8-TPP)-FeIII-(CN)2-{Cu II(TMPA)}2]3+ (6) [py = pyridine, TMPA = tris(2-pyridylmethyl)amine, and (F8-TPP) = tetrakis-(2,6-difluorophenyl)porphyrinate(2-)]. [CuII(TMPA)(CH3CN)](ClO4)2 and [(py)(F8-TPP)FeIII(CN)] (3) react to yield 5, while 6 is formed by combination of [CuII(TMPA)(CN)]PF6 (2-(PF6)) and [(F8-TPP)FeIII(PF6)] (4). Complex 2-(PF6) crystallizes in the orthorhombic space group Iba2 with a = 17.2269(5) {\AA}, b = 17.3143(4) {\AA}, and c = 14.4971(4) {\AA}, Z = 8, complex (5-(Sb/P)F6)1.5(ClO4)0.5 was obtained in the orthorhombic space group P222 with a = 17.9541(2) {\AA}, b = 20.5359(1) {\AA}, and c = 21.2023(2) {\AA}, Z = 4, and 6-(PF6)3 crystallized in the monoclinic space group P21/c with a = 15.318(4) {\AA}, b = 33.921(2) {\AA}, and c = 19.649(6) {\AA}, β = 109.69(2)°, and Z = 4. Compound 5 possesses a low-spin iron(III) center, bridged via cyanide to copper. The iron-cyanide vector deviates slightly from linearity (174.6(5)°). The copper(II) ion is five-coordinated by the TMPA N-donor atoms and the cyanide carbon atom. The Cu(TMPA) moiety is bent with an angle of 163.8(5)° around the cyanide-copper vector. Compound 6 possesses a low-spin iron(III) atom axially coordinated by two cyanide ligands capped on either side by trigonally coordinated [Cu(TMPA)] moieties. The [Cu(1)(TMPA)] unit is twisted somewhat (∠Cu1-N≡C = 168°), whereas the [Cu(2)(TMPA)] unit is coordinated in a nearly linear fashion with respect to the cyanide-iron vector (∠Cu2-N≡C4 = 175°). 1H and 2H NMR spectroscopy on 5 and 6 confirmed the low-spin nature of these iron complexes (pyrrole resonance found at -11.1 and -8 ppm, respectively). The NMR data as well as observed solution magnetic moment (μB = 2.7 for 5; μB = 3.4 for 6) suggest ferromagnetic coupling between the paramagnetic metal ions. This gives rise to an enhancement of the electronic relaxation rate for Cu(II) in both 5 and 6 allowing for the observation of the sharp and downfield shifted TMPA ligand proton signals.",
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TY - JOUR

T1 - Synthesis, structure, and solution NMR studies of cyanide-copper(II) and cyanide-bridged iron(III)-copper(II) complexes

AU - Corsi, Daniele M.

AU - Murthy, Narasimha N.

AU - Young, Victor G.

AU - Karlin, Kenneth D.

PY - 1999/12/1

Y1 - 1999/12/1

N2 - A range of small molecules, such as cyanide, are known to bind and/or inhibit the active site of the heme-copper oxidase enzymes. As such, model studies are aimed at elucidating ligand binding modes and their subsequent impact on spectroscopic properties of derived complexes. We describe here the isolation and characterization of two compounds containing the Fe-CN-Cu moiety, [(py)(F8-TPP)FeIII-CN-CuII(TMPA)]2+ (5) and [(F8-TPP)-FeIII-(CN)2-{Cu II(TMPA)}2]3+ (6) [py = pyridine, TMPA = tris(2-pyridylmethyl)amine, and (F8-TPP) = tetrakis-(2,6-difluorophenyl)porphyrinate(2-)]. [CuII(TMPA)(CH3CN)](ClO4)2 and [(py)(F8-TPP)FeIII(CN)] (3) react to yield 5, while 6 is formed by combination of [CuII(TMPA)(CN)]PF6 (2-(PF6)) and [(F8-TPP)FeIII(PF6)] (4). Complex 2-(PF6) crystallizes in the orthorhombic space group Iba2 with a = 17.2269(5) Å, b = 17.3143(4) Å, and c = 14.4971(4) Å, Z = 8, complex (5-(Sb/P)F6)1.5(ClO4)0.5 was obtained in the orthorhombic space group P222 with a = 17.9541(2) Å, b = 20.5359(1) Å, and c = 21.2023(2) Å, Z = 4, and 6-(PF6)3 crystallized in the monoclinic space group P21/c with a = 15.318(4) Å, b = 33.921(2) Å, and c = 19.649(6) Å, β = 109.69(2)°, and Z = 4. Compound 5 possesses a low-spin iron(III) center, bridged via cyanide to copper. The iron-cyanide vector deviates slightly from linearity (174.6(5)°). The copper(II) ion is five-coordinated by the TMPA N-donor atoms and the cyanide carbon atom. The Cu(TMPA) moiety is bent with an angle of 163.8(5)° around the cyanide-copper vector. Compound 6 possesses a low-spin iron(III) atom axially coordinated by two cyanide ligands capped on either side by trigonally coordinated [Cu(TMPA)] moieties. The [Cu(1)(TMPA)] unit is twisted somewhat (∠Cu1-N≡C = 168°), whereas the [Cu(2)(TMPA)] unit is coordinated in a nearly linear fashion with respect to the cyanide-iron vector (∠Cu2-N≡C4 = 175°). 1H and 2H NMR spectroscopy on 5 and 6 confirmed the low-spin nature of these iron complexes (pyrrole resonance found at -11.1 and -8 ppm, respectively). The NMR data as well as observed solution magnetic moment (μB = 2.7 for 5; μB = 3.4 for 6) suggest ferromagnetic coupling between the paramagnetic metal ions. This gives rise to an enhancement of the electronic relaxation rate for Cu(II) in both 5 and 6 allowing for the observation of the sharp and downfield shifted TMPA ligand proton signals.

AB - A range of small molecules, such as cyanide, are known to bind and/or inhibit the active site of the heme-copper oxidase enzymes. As such, model studies are aimed at elucidating ligand binding modes and their subsequent impact on spectroscopic properties of derived complexes. We describe here the isolation and characterization of two compounds containing the Fe-CN-Cu moiety, [(py)(F8-TPP)FeIII-CN-CuII(TMPA)]2+ (5) and [(F8-TPP)-FeIII-(CN)2-{Cu II(TMPA)}2]3+ (6) [py = pyridine, TMPA = tris(2-pyridylmethyl)amine, and (F8-TPP) = tetrakis-(2,6-difluorophenyl)porphyrinate(2-)]. [CuII(TMPA)(CH3CN)](ClO4)2 and [(py)(F8-TPP)FeIII(CN)] (3) react to yield 5, while 6 is formed by combination of [CuII(TMPA)(CN)]PF6 (2-(PF6)) and [(F8-TPP)FeIII(PF6)] (4). Complex 2-(PF6) crystallizes in the orthorhombic space group Iba2 with a = 17.2269(5) Å, b = 17.3143(4) Å, and c = 14.4971(4) Å, Z = 8, complex (5-(Sb/P)F6)1.5(ClO4)0.5 was obtained in the orthorhombic space group P222 with a = 17.9541(2) Å, b = 20.5359(1) Å, and c = 21.2023(2) Å, Z = 4, and 6-(PF6)3 crystallized in the monoclinic space group P21/c with a = 15.318(4) Å, b = 33.921(2) Å, and c = 19.649(6) Å, β = 109.69(2)°, and Z = 4. Compound 5 possesses a low-spin iron(III) center, bridged via cyanide to copper. The iron-cyanide vector deviates slightly from linearity (174.6(5)°). The copper(II) ion is five-coordinated by the TMPA N-donor atoms and the cyanide carbon atom. The Cu(TMPA) moiety is bent with an angle of 163.8(5)° around the cyanide-copper vector. Compound 6 possesses a low-spin iron(III) atom axially coordinated by two cyanide ligands capped on either side by trigonally coordinated [Cu(TMPA)] moieties. The [Cu(1)(TMPA)] unit is twisted somewhat (∠Cu1-N≡C = 168°), whereas the [Cu(2)(TMPA)] unit is coordinated in a nearly linear fashion with respect to the cyanide-iron vector (∠Cu2-N≡C4 = 175°). 1H and 2H NMR spectroscopy on 5 and 6 confirmed the low-spin nature of these iron complexes (pyrrole resonance found at -11.1 and -8 ppm, respectively). The NMR data as well as observed solution magnetic moment (μB = 2.7 for 5; μB = 3.4 for 6) suggest ferromagnetic coupling between the paramagnetic metal ions. This gives rise to an enhancement of the electronic relaxation rate for Cu(II) in both 5 and 6 allowing for the observation of the sharp and downfield shifted TMPA ligand proton signals.

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