Synthesis, crystal structures, electronic structure and magnetic behaviour of the trithiatriazapentalenyl radical, C2S3N3

被引:111
作者
McManus, GD
Rawson, JM
Feeder, N
van Duijn, J
McInnes, EJL
Novoa, JJ
Burriel, R
Palacio, F
Oliete, P
机构
[1] Univ Cambridge, Dept Chem, Cambridge CB2 1EW, England
[2] Univ Manchester, Dept Chem, EPSRC CW EPR Serv Ctr, Manchester M13 9PL, Lancs, England
[3] Univ Barcelona, Dept Quim Fis, E-08028 Barcelona, Spain
[4] Univ Barcelona, CER Quim Teor, E-08028 Barcelona, Spain
[5] Univ Zaragoza, CSIC, Inst Ciencia Mat Aragon, E-50009 Zaragoza, Spain
关键词
D O I
10.1039/b103303b
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
A novel synthesis of the title compound, C2S3N3 (1) is reported. X- and K-band EPR spectra on dilute solutions of 1 indicate delocalisation of the unpaired spin density over both heterocyclic rings in agreement with DFT calculations. An XRPD study indicates that it crystallises in two morphologies with both phases formed during vacuum sublimation. The XRPD studies indicate that on cooling below 230 K, only the triclinic phase (P (1) over bar) becomes detectable, whereas on warming above 320 K, just the monoclinic phase (P2(1)/c) becomes observed. The crystal structure of the monoclinic phase has been examined by variable temperature single crystal X-ray diffraction in the region 300-225 K and reveals a regular pi -stacked structure. A crystal structure of the triclinic phase is reported at 150 K and exhibits a dimeric pi -stacked motif. Susceptibility measurements show that the monoclinic phase is paramagnetic whereas the triclinic phase is diamagnetic. This radical exhibits thermal hysteresis with a wide range of bistability; EPR and magnetic susceptibility measurements indicate Tc-down arrow = 234 K, and Tc-up arrow = 317 K. The magnetic behaviour of the monoclinic phase is consistent with strong antiferromagnetic exchange interactions between open shell doublet states (J = -320 K) along the pi -stacking direction, although significant inter-stack interactions are required to model the data adequately. In contrast the dimeric phase is essentially diamagnetic, with the residual paramagnetism indicating a very large singlet-triplet separation (|2J| > 2000 K). The magnetic exchange interactions in both phases are probed through a series of DFT calculations using the broken-symmetry approach. These confirm the presence of strong magnetic exchange interactions along the pi -stacking direction in the high temperature phase (2J = -182 K), but with additional interstack interactions which are an order of magnitude smaller. Calculations on the triclinic phase indicate that it is best considered as a dimer with an open-shell singlet state with a very large singlet-triplet separation (2J = -2657 K). The magnitude of J for both phases from theory and experiment are in good agreement. The origin of the thermal hysteresis is attributed to the presence of two energetically similar structures which have a low energy barrier to interconversion. The thermodynamic parameters associated with the interconversion process have been probed by DSC studies. It confirms the first order nature of the transition with Tc-down arrow = 232.3 K (DeltaH(down arrow) = 1.41 kJ mol(-1), DeltaS(down arrow) = 6.0 J mol(-1) K-1) and Tc-up arrow = 320.5 K (DeltaH(up arrow) = 1.86 kJ mol(-1), DeltaS(up arrow) = 5.8 J mol(-1) K-1).
引用
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页码:1992 / 2003
页数:12
相关论文
共 58 条
[1]   A CW-EPR and ESEEM spectroscopic study of the dithiadiazolyl radicals p-XC6F4CNSSN (X = CN, Br) [J].
Alonso, PJ ;
Antorrena, G ;
Martínez, JI ;
Novoa, JJ ;
Palacio, F ;
Rawson, JM ;
Smith, JNB .
APPLIED MAGNETIC RESONANCE, 2001, 20 (1-2) :231-247
[2]  
[Anonymous], ELECT PARAMAGNETIC R
[3]  
Antorrena G, 1997, PHOSPHORUS SULFUR, V124, P133
[4]   A novel paramagnetic dithiadiazolyl radical:: Crystal structure and magnetic properties of p-BrC6F4CNSSN• [J].
Antorrena, G ;
Davies, JE ;
Hartley, M ;
Palacio, F ;
Rawson, JM ;
Smith, JNB ;
Steiner, A .
CHEMICAL COMMUNICATIONS, 1999, (15) :1393-1394
[5]   A COMPARATIVE ELECTRON-SPIN RESONANCE STUDY OF THE SELENOTHIADIAZOLYL RADICALS CYCLO-SE3-NSNN2+ (N = 0-3) [J].
AWERE, E ;
PASSMORE, J ;
PRESTON, KF ;
SUTCLIFFE, LH .
CANADIAN JOURNAL OF CHEMISTRY-REVUE CANADIENNE DE CHIMIE, 1988, 66 (07) :1776-1780
[6]   THE HIGH-YIELD PREPARATION, CHARACTERIZATION, AND GAS-PHASE STRUCTURE OF THE THERMALLY STABLE CF3CSNSCCF3., 4,5-BIS(TRIFLUOROMETHYL)-1,3,2-DITHIAZOLYL AND THE X-RAY CRYSTAL-STRUCTURE OF BENZO-1,3,2-DITHIAZOLYL [J].
AWERE, EG ;
BURFORD, N ;
MAILER, C ;
PASSMORE, J ;
SCHRIVER, MJ ;
WHITE, PS ;
BANISTER, AJ ;
OBERHAMMER, H ;
SUTCLIFFE, LH .
JOURNAL OF THE CHEMICAL SOCIETY-CHEMICAL COMMUNICATIONS, 1987, (02) :66-69
[7]   X-RAY CRYSTAL-STRUCTURES OF THE 1,3,2-BENZODITHIAZOLYL DIMER AND 1,3,2-BENZODITHIAZOLIUM CHLORIDE SULFUR-DIOXIDE SOLVATE - COMPARISON OF THE MOLECULAR AND ELECTRONIC-STRUCTURES OF THE 10-PI-ELECTRON C6H4S2N+ CATION AND THE C6H4S2N. RADICAL AND DIMER AND A STUDY OF THE VARIABLE-TEMPERATURE MAGNETIC-BEHAVIOR OF THE RADICAL [J].
AWERE, EG ;
BURFORD, N ;
HADDON, RC ;
PARSONS, S ;
PASSMORE, J ;
WASZCZAK, JV ;
WHITE, PS .
INORGANIC CHEMISTRY, 1990, 29 (23) :4821-4830
[8]   Modification of molecular packing: crystal structures and magnetic properties of monomeric and dimeric difluorophenyl-1,2,3,5-dithiadiazolyl radicals [J].
Banister, AJ ;
Batsanov, AS ;
Dawe, OG ;
Herbertson, PL ;
Howard, JAK ;
Lynn, S ;
May, I ;
Smith, JNB ;
Rawson, JM ;
Rogers, TE ;
Tanner, BK ;
Antorrena, G ;
Palacio, F .
JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS, 1997, (15) :2539-2541
[9]   THE FIRST SOLID-STATE PARAMAGNETIC 1,2,3,5-DITHIADIAZOLYL RADICAL - X-RAY CRYSTAL-STRUCTURE OF [P-NCC6F4CNSSN]CENTER-DOT [J].
BANISTER, AJ ;
BRICKLEBANK, N ;
CLEGG, W ;
ELSEGOOD, MRJ ;
GREGORY, CI ;
LAVENDER, I ;
RAWSON, JM ;
TANNER, BK .
JOURNAL OF THE CHEMICAL SOCIETY-CHEMICAL COMMUNICATIONS, 1995, (06) :679-680
[10]   Spontaneous magnetization in a sulfur-nitrogen radical at 36 K [J].
Banister, AJ ;
Bricklebank, N ;
Lavender, I ;
Rawson, JM ;
Gregory, CI ;
Tanner, BK ;
Clegg, W ;
Elsegood, MRJ ;
Palacio, F .
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION IN ENGLISH, 1996, 35 (21) :2533-2535