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

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species is stable and could potentially be isolated. The cyclic voltammogram is depicted in Figure 3-6 which outlines the conditions under which the experiment was performed. Figure 3-6. Cyclic voltammogram of III-3 showing the reversible oxidation with E ½ = 0.95 V, ΔE pp = 120 mV and an irreversible reduction at -0.683 V. CH 3 CN, n Bu 4 PF 6 (0.1 M), 3mM analyte, 100 mV/s, referenced against SCE with fc/fc + as internal standard set to E ½ = 0.40 V. 3.4 Discussion Quinones have rich and well explored electrochemical properties primarily due to the fact that they can take on three different oxidation states which can easily be examined using cyclic voltametry and other electrochemical methods. These oxidation states are depicted in Figure 3-6 and each is changed by the addition or removal of one electron. The quinone state on the far right is neutral and the removal of the first electron gives a negatively charged species. This is referred to as a semi-quinone and due to the odd 117
number of electrons that this compound possesses is a radical. Removal of a second electron results in a closed-shell dianionic species referred to as a catacholate. 3 When a 1,2,3-DTA fragment is introduced into the molecular architecture the possibility of a positively charged oxidation state is introduced. In addition, the 1,2,3-DTA ring is good Figure 3-7. Oxidation states of quinone based molecular systems. at stabilizing unpaired electrons which offers a potential for enhancing the effectiveness of these different oxidation states. The addition of this ring moiety however alters the radical nature of the quinone series such that the neutral quinone and the catecholate have unpaired electrons and the semi-quinone will be closed-shell. Examination of III-1 and its related compounds showed that the 1- oxidation state which is similar to the semi-quinone from Figure 3-6, is stable and isolatable as the lithium salt by reaction of III-1 with lithium hydride or n BuLi and has also been isolated in situ with sodium and triethyl ammonium counterions. It was also shown that the anionic form could be obtained from electrochemical reduction of the open-shell species III-2. However further electrochemical reduction of the radical species and the protonated compound III-1 in solution revealed only an irreversible process indicating that the second radical species with both oxygen atoms reduced (which resembles the 118
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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.................
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LIST OF FIGURES AND SCHEMES Figure
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Figure 2-12. Magnetic susceptibilit
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GLOSSARY OF ABBREVIATIONS ° Degree
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K k k B LMCT ls LUMO Kelvin Exchang
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LIST OF STRUCTURES I-1 I-2 I-3 I-4
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I-16a I-16b I-16c I-16d I-16e I-16f
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I-22 I-23 I-24 I-25 exo I-26 endo x
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I-34 I-35 II-3 II-4 II-1 xxv
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III-2 III-1 III-3 III-4 III-5 III-6
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V-7 V-8 V-9 V-10 V-11 V-12 V-13 V-1
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Chapter 1 - General Introduction 1.
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linear relationship shown in Figure
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A plot of χT vs. T is an important
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examination of phenyl methylene. In
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different atomic nuclei. Qualitativ
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3) 14 and a variety of thiazyl base
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with one another with an energy bar
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magnetic properties and undergoes a
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heteroatoms which could facilitate
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Figure 1-5. Qualitative molecular o
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temperature. 64 This was a very imp
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dimerization and therefore a quench
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e enough to overcome the energetica
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eaches the lower end of the investi
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DTDAs has been to exploit the rearr
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1.3.4 1,2,3-Dithiazolyl Radicals (I
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aromatic ring not only protects the
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is quite similar to the spin-polari
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compound there are many competing m
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a b c d e Figure 1-16. a) Nonorthog
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would result in non-orthogonal over
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platinum center as well as the phos
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substantial amount of unpaired elec
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I-28 I-29 I-30 The metals manganese
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gave a combination of 2 mononuclear
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changes related to geometric, chemi
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Finally, the last chapter reviews t
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(23) Rajca, A. Chem. Rev. 1994, 94,
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(53) Azuma, N.; Tsutsui, K.; Miura,
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(79) Decken, A.; Cameron, T. S.; Pa
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(102) Herz, R.; Leopold Cassella &
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(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
Page 113 and 114: contacts into four different intera
Page 115 and 116: e acting as a closed-shell, S = 0,
Page 117 and 118: 2.3.4 [Zn(hfac) 2 ] 2·pymDTDA (II-
Page 119 and 120: ancillary ligands and the nearly oc
Page 121 and 122: single molecular unit. Upon closer
Page 123 and 124: across the entire temperature regim
Page 125 and 126: 2.5 Conclusions and Future Work It
Page 127 and 128: therefore chain formation. However
Page 129 and 130: The work presented in this chapter
Page 131 and 132: 736(s), 723(s), 646(s), 632(s), 469
Page 133 and 134: (0.2023 g, 1.104 mmol) in 30 mL of
Page 135 and 136: (6) Chattoraj, S. C.; Cupka Jr, A.
Page 137 and 138: Chapter 3 - 5-oxo-5H-naphtho[1,2-d]
Page 139 and 140: triethylammonium chloride which was
Page 141 and 142: 3.3.2 Mass Spectrometry A sample of
Page 143 and 144: 3.3.4 X-ray Crystallography Crystal
Page 145: a 2-fold screw axis across half of
Page 149 and 150: often generated in situ although wa
Page 151 and 152: similar to compounds II-1 and II-2,
Page 153 and 154: 3.6 Experimental General All reacti
Page 155 and 156: Chapter 4 - The Polymorphism of Tri
Page 157 and 158: 4.3 Discussion Prior to the discove
Page 159 and 160: (derived from angles ranging from 4
Page 161 and 162: a b c Figure 4-2. Packing diagrams
Page 163 and 164: polymorphs observed and are therefo
Page 165 and 166: Chapter 5 5.1 Overview There are se
Page 167 and 168: success and so a Herz ring closure
Page 169 and 170: did not immediately precipitate, bu
Page 171 and 172: Figure 5-2 shows the IR spectra for
Page 173 and 174: comparison of the infrared data obt
Page 175 and 176: discussed in section 5.2.2. As the
Page 177 and 178: ing was formed. One of the nitrogen
Page 179 and 180: equired to obtain a decent agreemen
Page 181 and 182: Considerations have been put toward
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Page 185 and 186: the mixture was filtered to remove
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Page 189 and 190: spectrum from about 1900 to 400 cm
Page 191 and 192: doublets of triplets associated wit
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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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1,2,3-Dithiazolyl and 1,2,35-Dithiadiazolyl Radicals as Spin-Bearing ...

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