Magnetic behaviour of octaethylporphyrinatomanganese(III) tetracyanoethenide, [MnOEP][TCNE], and hexacyanobutadienide, [MnOEP][C4(CN)6]: the importance of a uniform chain for stabilizing strong effective ferromagnetic coupling

Miller, Joel S.; Vazquez, Carlos; Jones, Nancy Lee; McLean, R. S.; Epstein, Arthur J.

doi:10.1039/jm9950500707

Cited by 57 publications

(62 citation statements)

References 14 publications

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“…The Mn-N-C 160.0 (10)8 angle is midway between that of [MnTtBuPP][HCBD] [5] (172.38), and [MnOEP][HCBD] (148.18) which has different bonding motif. [4] The dihedral angle between the MnN 4 plane and plane of one half of [HCBD] .À is 83.7(3)8 close to that found for [MnTtBuPP][HCBD] (87.48). [5] In the structurally related [MnTPP][TCNE] family of magnets, it has been shown that this angle is inversely proportional to the strength of the 1-D antiferromagnetic coupling between the Mn III and [TCNE] .À .…”

Section: Resultssupporting

confidence: 68%

“…[4] These data are less than that found for either with [MnTtBuPP][HCBD] (1.445 ) [5] or [MnOEP][HCBD] (1.433 ). [4] The CN bond distances for the exo-, endo-and interior positions range from 1.139(5) to 1.167(5), and average 1.156 . The N-C-C bond angles average 175.18, whereas the NC-C-C bond angles average 121.28.…”

Section: Resultsmentioning

confidence: 78%

“…[7] Nonetheless, these values are inconsistent both unbound [HCBD] .À , such as [FeCp* 2 ] [HCBD] (Cp* pentamethylcyclo-pentadienide) [2185 (s) and 2168 (m) cm À1 ], [8] or either mode of trans-N-sbound [HCBD] .À (A or B). [4,5] The n Ä CN for a-2 Clpy is inconsistent with known [HCBD] .À complexes. [6,7] The 2128 cm À1 absorption suggests a new structural arrangement for reduced HCBD.…”

Section: Resultsmentioning

confidence: 99%

“…[4] Due to the ease of modifying the porphyrin structure, we are studying electrontransfer salts of substituted-Mn II TPP complexes with HCBD to identify factors responsible for differences in [HCBD] .À binding and subsequent magnetic coupling. Herein, we report the structural, chemical, magnetic, and thermal properties of several HCBD electron transfer salts with mesotetrakis(4-chlorophenyl)porphinatomanganese(ii) pyridine [Mn II TClPPpy] (1 Clpy), and meso-tetrakis(4-bromophenyl)porphinatomanganese(ii) pyridine [Mn II TBrPPpy] (1 Br).…”

Section: Introductionmentioning

confidence: 99%

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Products from the Reaction ofmeso-Tetrakis(4-halophenyl)porphinato-manganese(II) and Hexacyanobutadiene (HCBD): Formation of π-[HCBD]22− Dimers,μ-[HCBD].−, σ-[HCBD].−, and [C4(CN)5O]−

et al. 2000

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The reaction of hexacyanobutadiene (HCBD) and meso-tetrakis(4-chlorophenyl)porphinatomanganese(II) pyridine [MnIITClPPpy] (1Cl) leads to two phases of [MnIIITClPPpy][HCBD].PhMe (alpha-2Clpy, beta-2Clpy). Similarly, the reaction of HCBD and tetrakis(4-bromophenyl)porphinatomanganese(II) pyridine [MnIITBrPPpy] (1Br) leads to two products [MnIIITBrPPpy] [HCBD] * PhMe (2 Brpy) and [MnIIITBrPP][HCBD]*2 PhMe (3Br). The structure of dark-green alpha-2Clpy consists of one porphyrin unit with MnIII in a square pyramidal coordination environment axially bound to one pyridine. The cation forms [MnIIITCIPPpy](2)2+ as cofacial dimerized porphyrins. Each [HCBD]*- is nonplanar with a torsion angle of 170.8(4) degrees about the center C-C bound, and forms [HCBD](2)2- dimers in the solid state with sub-van der Waals contacts of 3.325 and 3.340 angstroms. The magnetic data above 10 K obey the Curie-Weiss expression with a theta of -2.5 K, and mueff (300 K) = 4.91 muB as expected for S=2MnIII and S = 0 [HCBD](2)2-. The magnetic data for alpha-2Clpy can be fit with an zero-field-splitting D of -1.45 K. beta-2 Clpy consists of one porphyrin unit with MnIII in a distorted octahedral coordination environment axially bound to py and to a monodentate [HCBD]*- bound via an exo-nitrile. [HCBD]*- is nonplanar with a torsion angle of 169.7(5) degrees about the center C-C bound. The ueff (350 K) is 5.09 muB; however, the magnetic data do not obey the Curie-Weiss expression above 70 K. The low temperature data may be fit with a theta of -5.4 K. The data was modeled to an isolated S = 2 and S = 1/2 dinuclear spin system with J/kappaB = - 90 K. Decomposition of [HCBD]*- to [C4(CN)5O]- was evidenced by the determination of the structure of [MnIIITCIPP][C4(CN)5O] 2PhMe (3ClO). Crystals of 3 Cl-O were prepared by reaction of HCBD and 1Cl in the presence of a drop of water. The molecular structure consists of [HCBD]*-trans-mu-N-2,3-bound to [MnIIITBrPP]+ forming a 1-D coordination polymer of alternating [MnIIITBrPP]+ and [HCBD]*-. The intrachain Mn***Mn distance was 10.675(3) angstroms, with important interchain Mn***Mn distances of 10.832, 11.016, and 14.696 A. The magnetic data were fit to a Curie-Weiss law (10 < T< 290 K) with a theta of -3.5 K, and D = 0.3 K with mueff = 4.97 muB at 300 K.

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Section: Resultssupporting

confidence: 68%

Section: Resultsmentioning

confidence: 78%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Products from the Reaction ofmeso-Tetrakis(4-halophenyl)porphinato-manganese(II) and Hexacyanobutadiene (HCBD): Formation of π-[HCBD]22− Dimers,μ-[HCBD].−, σ-[HCBD].−, and [C4(CN)5O]−

et al. 2000

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“…Another class of Mn(III) complex that has been used for assembly of magnetic materials employs metal coordination by porphyrinic ligands [11][12][13]. Again, the electronic structure of the individual complex is crucial in understanding the material's bulk properties.…”

mentioning

confidence: 99%

High-frequency and -field electron paramagnetic resonance of high-spin manganese(III) in axially symmetric coordination complexes

Krzystek¹,

Telser²,

Knapp³

et al. 2001

Appl. Magn. Reson.

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High-frequency and -field electron paramagnetic resonance (HFEPR) has been used to study several complexes of high-spin manganese(III) (3d4, S = 2): [Mn(Me2dbm)X] and [Mn(OEP)X] (X = Cl-, Br -), where Meidbm-is the anion of 4,4'-dimethyldibenzoylmethane and OEP 2-is the dianion of 2,3,7,8,12,13,17,18-octaethylporphine. These non-Kramers (integer spin) systems are not EPR-active with conventional magnetic fields and microwave frequencies. However, use of fields up to 15 T in combination with multiple frequencies in the range of 95-550 GHz allows observation of richly detailed EPR spectra. Analysis of the field-and frequency-dependent HFEPR data allows accurate determination of the following spin Hamiltonian parameters for these complexes: [Mn(Me,dbm)Cl], D = -2.45(3) cm'; [Mn(Me2dbm)Br], D = -1.40(2) cm'; [Mn(OEP)Cl], D = -2.40(1) cm'; [Mn(OEP)Br], D = -1.07 (1) cm -' (E 0, and g 2.0 in all cases). Comparison of structural data with the electronic parameters for these and related complexes shows quantitatively the effects of axial and equatorial ligation on the electronic structure of Mn(III). These high-spin complexes can be employed as building blocks in the construction of single-molecule magnets. Thus the accurate determination and understanding of the electronic properties, best obtainable by HFEPR, of these monomeric units is important in understanding and improving the properties of the polynuclear single-molecule magnets which can be formed from them. IntroductoinPolynuclear transition metal clusters that possess large ground-state spins (S > 4) are of significant interest for use as magnetic materials. In particular, high-spin molecules with large-magnitude, negative zero-field splitting (zfs) (D < 0) exhibit magnetic hysteresis effects resembling nanomagnets and are termed single-molecule magnets (SMMs) [1][2][3][4][5][6][7][8][9]. The resultant zfs of a polynuclear complex reflects * Present address:

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Supramolekulare Aggregate heterogener Multiporphyrinanordnungen – die Strukturen von [{ZnII(tpp)}2(tpyp)] und dem Koordinationspolymer [{[MnIII(tpp)]2(tpyp)(ClO4)2}∞]

Kumar

Goldberg

1998

Angewandte Chemie

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46% des Kristallvolumens machen Kanäle aus: Aus [MnIII(tpp)]⋅ClO4 und tpyp bildet sich ein zweidimensionales Koordinationspolymer von außergewöhnlicher Regelmäßigkeit (siehe schematische Darstellung; tpp=Tetraphenylporphyrin, tpyp=Tetrapyridylporphyrin). Durch die Kristallpackung dieser Polymere entsteht eine offene Endlosstruktur mit Netzen rechtwinkliger Kanäle, die mit Nitrobenzol als Solvens gefüllt sind. Bei der Reaktion von [ZnII(tpp)] mit tpyp entstehen hingegen nur oligomere Strukturen.

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Magnetic behaviour of octaethylporphyrinatomanganese(III) tetracyanoethenide, [MnOEP][TCNE], and hexacyanobutadienide, [MnOEP][C4(CN)6]: the importance of a uniform chain for stabilizing strong effective ferromagnetic coupling

Cited by 57 publications

References 14 publications

Products from the Reaction ofmeso-Tetrakis(4-halophenyl)porphinato-manganese(II) and Hexacyanobutadiene (HCBD): Formation of π-[HCBD]22− Dimers,μ-[HCBD].−, σ-[HCBD].−, and [C4(CN)5O]−

Products from the Reaction ofmeso-Tetrakis(4-halophenyl)porphinato-manganese(II) and Hexacyanobutadiene (HCBD): Formation of π-[HCBD]22− Dimers,μ-[HCBD].−, σ-[HCBD].−, and [C4(CN)5O]−

High-frequency and -field electron paramagnetic resonance of high-spin manganese(III) in axially symmetric coordination complexes

Supramolekulare Aggregate heterogener Multiporphyrinanordnungen – die Strukturen von [{ZnII(tpp)}2(tpyp)] und dem Koordinationspolymer [{[MnIII(tpp)]2(tpyp)(ClO4)2}∞]

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