1,2,3-Dithiazolyl and 1,2,35-Dithiadiazolyl Radicals as Spin-Bearing ...

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such as ferrocene or related compounds. 109 The choice of reagent depends on the reduction potential which can been determined electrochemically. 110 The SOMO for this radical is similar to that for the 1,2,3,5-DTDAs already discussed which places some electron density on one of the carbon atoms. 109 The result is that any substituent on this carbon atom will also have some spin density either from expanding the SOMO over a larger molecular area or through spin polarization. Figure 1-11. Generic 1,2,3-DTA ring illustrating the positions of the respective atoms (left) and the SOMO for the 1,2,3-ring with a node at the carbon adjacent to the nitrogen (right). The compound 2,5-dichloro-1,2,3-dithiazolium chloride, also known as Appel’s salt (I-17a) 132 was doubly reduced to afford the a carbon-carbon bridged dimer (1-17b) and the radical (I-17c), a presumed intermediate, was not detected by EPR spectroscopy likely because the association and subsequent reduction occur too quickly. 111,112 The benzo-fused DTA systems are therefore much more interesting as their connection to the Scheme 1-3. Double reduction of I-17a to give I-17b. I-17c 32
aromatic ring not only protects the spin-bearing carbon of the heterocycle from the irreversible formation of a carbon-carbon bond, but also results in delocalizing the spin of the unpaired electron over the rest of the molecule through the extended π system, 113 which is an important criterion for enhanced stability of radical molecules. A number of benzo or naphtha-fused species have been investigated, although they seem to frequently suffer from reversible formation of the π-stacked, sulfur-sulfur bonded dimers which plagued the previous examples of thiazyl radicals. 114 Compound I-17d is one such example. As a result, the magnetic properties of many of these types of I-17d Figure 1-12. π-stacked dimers of I-17d. compounds have not sparked considerable interest in the magnetochemistry community. However, the Oakley group has been experiencing success with a bifunctional 1,2,3-DTA based radical framework (I-17e) which they have been tweaking with different R groups and the incorporation of selenium in the place of sulfur. 110 Many of these compounds do not form dimers, but form evenly spaced π-stacks which exhibit antiferromagnetic 33
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1,2,3-Dithiazolyl and 1,2,35-Dithia
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an individual binuclear coordinatio
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weren’t sure about something our
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2.1 General........................
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5.3 Reverse oDTANQ.................
Page 11 and 12: LIST OF FIGURES AND SCHEMES Figure
Page 13 and 14: Figure 2-12. Magnetic susceptibilit
Page 15 and 16: GLOSSARY OF ABBREVIATIONS ° Degree
Page 17 and 18: K k k B LMCT ls LUMO Kelvin Exchang
Page 19 and 20: LIST OF STRUCTURES I-1 I-2 I-3 I-4
Page 21 and 22: I-16a I-16b I-16c I-16d I-16e I-16f
Page 23 and 24: I-22 I-23 I-24 I-25 exo I-26 endo x
Page 25 and 26: I-34 I-35 II-3 II-4 II-1 xxv
Page 27 and 28: III-2 III-1 III-3 III-4 III-5 III-6
Page 29 and 30: V-7 V-8 V-9 V-10 V-11 V-12 V-13 V-1
Page 31 and 32: Chapter 1 - General Introduction 1.
Page 33 and 34: linear relationship shown in Figure
Page 35 and 36: A plot of χT vs. T is an important
Page 37 and 38: examination of phenyl methylene. In
Page 39 and 40: different atomic nuclei. Qualitativ
Page 41 and 42: 3) 14 and a variety of thiazyl base
Page 43 and 44: with one another with an energy bar
Page 45 and 46: magnetic properties and undergoes a
Page 47 and 48: heteroatoms which could facilitate
Page 49 and 50: Figure 1-5. Qualitative molecular o
Page 51 and 52: temperature. 64 This was a very imp
Page 53 and 54: dimerization and therefore a quench
Page 55 and 56: e enough to overcome the energetica
Page 57 and 58: eaches the lower end of the investi
Page 59 and 60: DTDAs has been to exploit the rearr
Page 61: 1.3.4 1,2,3-Dithiazolyl Radicals (I
Page 65 and 66: is quite similar to the spin-polari
Page 67 and 68: compound there are many competing m
Page 69 and 70: a b c d e Figure 1-16. a) Nonorthog
Page 71 and 72: would result in non-orthogonal over
Page 73 and 74: platinum center as well as the phos
Page 75 and 76: substantial amount of unpaired elec
Page 77 and 78: I-28 I-29 I-30 The metals manganese
Page 79 and 80: gave a combination of 2 mononuclear
Page 81 and 82: changes related to geometric, chemi
Page 83 and 84: Finally, the last chapter reviews t
Page 85 and 86: (23) Rajca, A. Chem. Rev. 1994, 94,
Page 87 and 88: (53) Azuma, N.; Tsutsui, K.; Miura,
Page 89 and 90: (79) Decken, A.; Cameron, T. S.; Pa
Page 91 and 92: (102) Herz, R.; Leopold Cassella &
Page 93 and 94: (128) Aliaga-Alcalde, N., 2003. (12
Page 95 and 96: Chapter 2 - Structural and Magnetic
Page 97 and 98: 2.2.2 pymDSDA Coordination Complexe
Page 99 and 100: 2.2.3 DTDA Coordination Complexes o
Page 101 and 102: indicators tend to be very weak str
Page 103 and 104: In Figure 2-1a, the nickel complex
Page 105 and 106: 2.2.3 Cyclic Voltametry The cyclic
Page 107 and 108: propensity for intermolecular Se-N
Page 109 and 110: dimerization motif. One possible ex
Page 111 and 112: the bridging ligand such that the D
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contacts into four different intera
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e acting as a closed-shell, S = 0,
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2.3.4 [Zn(hfac) 2 ] 2·pymDTDA (II-
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ancillary ligands and the nearly oc
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single molecular unit. Upon closer
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across the entire temperature regim
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2.5 Conclusions and Future Work It
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therefore chain formation. However
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The work presented in this chapter
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736(s), 723(s), 646(s), 632(s), 469
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(0.2023 g, 1.104 mmol) in 30 mL of
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(6) Chattoraj, S. C.; Cupka Jr, A.
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Chapter 3 - 5-oxo-5H-naphtho[1,2-d]
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triethylammonium chloride which was
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3.3.2 Mass Spectrometry A sample of
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3.3.4 X-ray Crystallography Crystal
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a 2-fold screw axis across half of
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number of electrons that this compo
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often generated in situ although wa
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similar to compounds II-1 and II-2,
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3.6 Experimental General All reacti
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Chapter 4 - The Polymorphism of Tri
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4.3 Discussion Prior to the discove
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(derived from angles ranging from 4
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a b c Figure 4-2. Packing diagrams
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polymorphs observed and are therefo
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Chapter 5 5.1 Overview There are se
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success and so a Herz ring closure
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did not immediately precipitate, bu
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Figure 5-2 shows the IR spectra for
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comparison of the infrared data obt
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discussed in section 5.2.2. As the
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ing was formed. One of the nitrogen
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equired to obtain a decent agreemen
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Considerations have been put toward
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chelation pocket is similar to that
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the mixture was filtered to remove
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good spectroscopic handle for this
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spectrum from about 1900 to 400 cm
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doublets of triplets associated wit
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adical, followed by the closed-shel
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completely dry after being under va
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changed substantially after the tra
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The reaction to produce V-15 was qu
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the proton two carbons away next to
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which is parallel to the mean plane
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of the 1,2,3-DTA rings could act as
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mixture was refluxed for 20 h yield
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the heat source was removed and the
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1085(w), 1059(w), 1008(w), 917(w),
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___________________________________
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Crystallography P 2 1 /c a = 9.1678
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Compound Name: 4-(2′-pyrimidyl)-1
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Compound Name: [μ-4-(2′-pyrimidy
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Magnetometry 192
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Crystallography P-1 a = 8.9576, b =
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Compound Name: [μ-4-(2′-pyrimidy
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Magnetometry: 198
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Crystallography: P2 1 /n a = 19.884
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Compound Name: 5-oxo-5H-naphtho[1,2
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204
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206
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MS (EI + ): 208
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Compound Name: 5-chloro-1H-[1,2,5]t
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Compound Name: 3-nitro-1,2-naphthaq
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Compound Name: 3,4-dioxo-3,4-dihydr
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Compound Name: 4,5-dioxo-4,5-dihydr
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Compound Name: 6,6′-dinitro-1,1
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220
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222
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1,2,3-Dithiazolyl and 1,2,35-Dithiadiazolyl Radicals as Spin-Bearing ...

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