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Magnetic circular dichroism of some benzene derivatives
:
'__
:
. .
..
Received 28 May 1974
I.
I
:'
'.
The hC'btp&traof phIoro$ucin,
1,3,5-trimelhoxyb2nzene, 1,3,5-trkyanobenzeoe, .13_5+rinitrobenzene,~ 1,3Jbenz’enetricarboxylic acid and 1,3,j‘..benzenctriolrbonyl chloride were measured. For the E' + ‘A;’ transition of phioroglucin or 1,3,5-tricyano~e’tlzene,and the ‘E’ t ‘A’ tknsitidn of 1,3,5_trin:e~oxybenzsne, the FaredayA term was observed and the&D&&e was esfnctcd_ However, 1,3,S-~~~obe~ene, 1,3~S-ben~ene~~~ho~ylic acid and 1,3,.5benzenetricarbonyl chloride showed no magnetic circular dichroism’ inthis spectral region. Themagnetic moments in the ‘E’ states of tbe!:e molecules. seem-to be quenched by the effect:; of substituents. The magnetic moments in the ‘E’ states of benzene derivatives are sensitive to substitution in the benzene ring. f
:
‘,
Magnetic cir&lar dichroism (MCD) has,been used. for the ~vestigation of electronic ~tructur~:s of or- .’ : ganic and inorganic compounds and polymers. There, ‘, are many studies which have deaJt with the magnetic circular dic~ojsm of benzenoid [l-g] and non,, I benzenoid [7-P] aromatic hydrocarbons.,’ .. ” Fecently we have reported the MCD SpCCtKi of. I I hexachlcro-, 1;3;5-trichlaro-, hexabromo- and ” II. I I : 1;3,5’-tribromobenzenes [lo], and extracted the : magnetic moment in the lElu state for each of these corripounds:,Herk we report and discuss the MCD .’ ., ~ectra’of,p~lorogluc~, 1;3,5-t~ethoxybe~zene, 1,3,.55-tricyanobenzene, 1,3,5_trinitrobenzkne; 1;3,5- ‘. ‘. Fig. 1. The lowest sin&et states of the be&ems dtrivat&. Solid and dashed vertiul lines denote the~$lowrd_and forbenzenetricarboxylic acid and 1,3$benzenefricarbidden transitions; iespectively. .’ bony1 chloride. The main purpose of t&s.work is’to : 1, ,. obtain the magnetic moment of the 1E’ state and in- 1) of,l3,5.trimetho’xybenzene, 1,3,5-benzeneformation about the effect of substitution in the. ,: :: t&&ions benzene ring onthe sign and ma~nit~de’?f the mag- 1 tri&rboxylic acid and. 1,3,5benzenet%ubonyIJ chlon&c mcnient in the IE’ state: ,’ ’ ride.may,be discussed by.as.sum&g that these moIe: symmetry. The singlet eIectronic states Accordmgto theoretica! considerations [11, i2], ,’ ,. cules ha&&, when either the ground or the excited state of a corn- .,: ‘, qrising ‘from onk-eIectron excitati;in from .tbe b&best ‘o&pied orb&Is to the lowest vacant orb%& are pound is degenerate, .the Faraday A’ferrri should be .’ observed. The degeneracy of the ground state causes ‘. g&n in. fig. j..In D&, and C3h symmetry; the 1El, k.the Faraday .C term. The Faraday B term arises from.. ’ ..’ IA- transition of’betiene tirresponds to the lF’-* -the mixing of the ~av~fun~~~~.ns’of ~he.groun~ an+ ., : ?A’;gand.l E’ + 1A’ t~ans~~io~, respectiireIyy, and .excited states withthose of bther ele+mi~ states by’ .. ‘Faraday A &ms can be expected for these electronic the’external magnetic field. The n:elec@od ‘systems of .‘.:,.., Jrahsirions. .,: ” 1,3,5-ben- . : ~~0~0~1~~~; 1,3,5~~~~~~~~~ene and ~;3,5-tri@o~’ ._! P~?rogl~~~,. 1,3 ,&methoqbenz+zene, 1 ,+%,.S-trinitrobenzene were benzene belong, to the_po&?t group, D,,.’ The ?rA, nt ‘1 : : ,.z&etrioarbo&lic aiid and . ; :. .‘. .. .. ,.:
.’ -, :.. ‘.
.: !, ,. /. . .. “. : :“, .: .s _.., .. : :: _ ‘... -’ “” : -:, .___. _, ; -.:. :_; _._,;:_:. .. . _,_ .::,- _ ,. .. .. . .I ,, ;._.’ :,.:, . . _: ‘, ._.‘._ : _‘. :, _ _..‘ ...-. .“ ., ;.. ., ,‘,, :: ., :.‘_.‘-.~I _. ., .-, : .’ :h. .’ ; ~.,.,,,, ,‘.: .” ,. ., : :s ,, ;_
: ‘.
_ . .._ _; ,, -: ,. : ., ,, , .’
197’ : ,_,“.;
.-
‘,
_,
:
,,.
._
LETERS.
CHEhf+AL~Pi+IC$ ~y&28,.hyrl& 2 .I, _, ._ . ..,:.L,. ; ., .‘, :’ ., _, &&eicidyQbtain& and ‘@b&l& b’$ rec&fa]la_ : :
,:
:ticirifrc&i water, ~t~a~ol,~~~t~r, and’e*anol, respf+- ’ iti~ely,andIinally dried ,in.vacu& On the tither hand, .. .’ :.!;3,5-b,eniknet~icarbonyl chloridi afid ‘1,3,5;tricyano’ :. be&ne,i~&e prepared’&ti~1,3,5-bertzerietricarb’oxI :.; yli&&d according to the probedtire offetied.by Skala : .‘~i~a~.~[~.~J and Bennett’etal. [14]: Thc’MCD and .’ ‘:. ,‘W spec&a w&e m&&&d &a‘JASCO J-20A reco;d: ) ing spg&opolarirrieter equipped with‘a 12S’kG elec‘tr&tiagnet and 9,n.a Hitachi~EfS-3T recording spectr~~hotom~t~r, respectively, at ioom temperature. .In figs. 2Gthe MCri (A) and UV (B).spectraof __ .‘&Ioroglucin, Id,s-trirr;et~qxyt;en~ene, I ,3,5-t&: %n6benz& anh 1,3;5&i&robenzenk ace &wn; In. ~e-~~~r-w~ven~be~ region, <4Si54) X lo3 ci7’, phlorogl@; 1,3,5-$imet.lq$Eenzene and 1,3,5-t&. .,
‘,._,
.‘
:.
:
,...
; ., ’
:
_
‘. 15 September 1974
.’
,.
..
_-
.
ICll JCllC
.’
‘.
‘. .-
‘-I-..
I..
-t-,
..
. . ‘,
1,
I I ..
‘.
:. ..‘.
‘, @!I %a!e
,_ :: right -5dr
Fig. 3. M&(A) aid I_Jv(Bj ~~peC.tia Of i,3~-t~i1WthO?W benzer,e in ti-hepiane %+&on at roorp temperature,
:
‘.
:’
I’ :. : !.‘_
.IE!,+ l&A;.or IE + IA’ knsition. and the inflection’ point of each A term coincides with ‘the absorption :maxiriun Within the hit pf ex~er~ent~ error. iithe MCD and absorption spectra of i,3,%tricyanobeni zene Tye C&-Jobserve fini kucture which is considered-, .. to be iibr&ic $ruct~re~due to the tqta.Uy symmetric ‘. .: vihratidns. For 1,,3,5-berizenetri~ibo~~~c acid;!,3,5be~~net~~bony~ chloride and- 1,3’,5$nnitiobenzene, no .m&etic’circular dichroi& was obietied’in thissp&itraI re&in. The mq$kic m&&nts in the IE’. states of these c?otipdqndsseemed to be Quenched.
Volume 2,8, ntiber.2.
.,
..
I.5 Septen-,ber 1974
CHEMICAL @HYSICS LETkERS ..
Fig. 4. MCD(A) and U%‘(B) spectra of i,3,%ricyanabenzene at room temperature. As solvents, acetonitiile and acetoniWile-water (1:4 in volume) were used in ihe region of : (31-45.5) X103 cm-’ and (45.5-54) X103 cm-‘, .‘. respdctively.
Fig. 5. MCD(A) md W(g) +ectra of 1.3~~t&itmbexxne at room temperature. As solvents, ethanol-rr-heptane (I:9 in . volume), ethanol-n-heptani (1~24 in voiume) and n-heptznc’ were used in theregion of (24-31) X IO3 cm-t, (31-36~3) X lo3 cm-l.and (36.3-51) X lo3 cm-‘, respectiveI>-.
.’ chroism in this spectral region, which is similar to the 34 X IO3 cm-l. The latter tmnsition indicated case of halogenobenzenes..[ 101. The asSignment of posirivo magkic circuk~ dichroism &$.I& no MCD these tra,n&tion bands in benzene and its deriiiatiies .. band occurs in the former region. Probably the n + was’discussed in our previous paper.’ [I 01. :. rr* transitions of carbonyl groups in 1,3$benzenoFor 1,3,5-trirrrethoxybenzene, 1,3,5-irlcyanobentricarboxylic acid and 1,35_b~nzenetricarbonyl zene and 1,3,5-benzenetiicarbonyl chloride, the corn-’ .’ chloride may be overlapped with the rr +=rr* trarzjiplieated MCD bands, which can’be assigned to the. l&f tions df the berkeile ring which will be stronger than. ‘Ai .-and, I’A’ + 1 A’ symketj-forbidden tranr the nr, 7r+ transitions.~ sitions, appeared in the lowest wavenumber region, The sign and magnitude of the magnetic moment .(3 l-41) X lo3 cm-.I , with the .i - sign, alternations;, while phloroglucin and 1,315benzenetricarboxyk ‘:’ ’ in the excited &ctronic.&ate can be discussed through t&k A/D value_where D is the dipote strength. FG~ the ; acid simply indicated negative and positt/e_magnetic circubu dichroism, respectively,in thik region; For ,. ‘.. :‘E’.& 1Ai .trar&ions of pfilorogIucin and 1,3,5-tri- ’ ’ cyannbbetiene and the lEr + IA’ transition’of 1,j,5-tdnitrobenzene;~the n * rr* transition was obl we obtained A/D and. tirved iri the region of (24-315) X 1‘03 cm-r’ and : .’ !;3 ,Strime@xybenxene, : B/D vah~s by the use of t&e’.method of moments the lowest B ;‘rr* .transition of the benzene ring .: a?$ u;M spectra. As Ferns to corre@ond to the shoulder at ‘:: : ,: ‘:‘.C[12] iprom .”+Jledbs&ved~MCD ,;. about ‘_ ..’ ,. .,: c ., ‘. ,’_::; -..,.._ :. ; : ., ‘. .. ; ‘, 199 ,:. .’ . ‘z.
z
Ex&ed,Faradai p,arame!ers,-for tht ‘J$+ irid D.6h’symme.~y,-respectiveiy .,,
Table 1 : .I ‘.. ... 'A', ‘i; + ‘A’, .and !EIU ‘- ‘,I; g tiqnsitiqns of benzene derivatives with Csh, D3h,
. v x ICI-~ (m-l)
phloldglucin’ 1~;5-trimetlloxyb.enzene 1,3,5-tricyanobe&h&: 1,3,5-trichlorobenten-a) 1,3,5-tribromobenzene”) .‘hexachIorobenzenea) hexabromobenzene a)
’
., .,
-,
‘.
:
49.7 49.2 48.0. 49.6 48.2 -46.4 44.2
_, d;b (p)’ -.
::_ : ‘, ‘.
0.323 0.301 ‘.. 0.182 0.207
:
:
‘.
.a).Froh-‘;ef..
;
‘-
-, .,_
-1.29 2.49 -2.35 -5.79
,0.172
I_ ‘.
i?/D’X,105 lj&rr’)
0.127 0.262
:
y
-.
:
-7.W : -1.98 -4.45
. .
[lo].
‘. -.
shotiii in table 1, the A/b values pf these molecules tire in agteemerit with those of halogetiobenzenes ” [lo] both in sfgn‘and ordei of magnitude. In the case of 1;3,5_trinitrobenz?ne, 1,3,5-benzenetiicarboxylic acid tid 1,3,.5-benzetietricarhonyl chldride, ‘:the magnetic moment is so small that no magnetic ~circ& dichroism wzs observed in the higher wavc“num!e;-regiqn:The magnetic moments in the 1E’ ‘states of benzene derivatives are sensitive i0 the effects .:,of substituents. EqIoration of these. e&per&mental residts di the SCF MO method is now under investigaiion;:_,‘._
_-
‘,
.:. :
;. -. ’ Riferims
[;I DJ. Shieh, S.H. Lin and H. Eyring,Proc. ki. US.69 (1972) 2000. [4] D.J. Caldwell and H. Eyring, J/&em.
Natl. Aad. Phys. 58 (1973)
1149:
[5], D.J. Shieh, S.H. Lin and H: Eyrk,
J. Phys. Chcm. 77 (1973) 1031. [6] 1.X. Doug& R. Grinter and A.J. Thomson, Mol. Phy;. 26 (1973) 1257. [7] A:Tajiri’and hf. Hatano, Bull. Chem. Sot. Japan $5 (1972) 952.’ ‘[B] H ..Uchimura, A: Tajiri and M. Hatano, Chem. Phys.
LMfPCS 19 (1973) 513. (91 A. Tajiri and Ml Hatano, Chem. Phys. ietters
25 (1974) 5f,6. [lO]‘A. Kaito, A. Tajti and M. Hatano, Chem. Phys. Letters
25 11974)54s. [ll]
-.
-. [I] P.J. Stephens, P.N. Schatz, AD. Ritchie and A.J. M,cCaffcry, !. Chcm.?hys 48 (1968) 132. [2] J.G. Foss and h1.E. M&ar~lle;-J., Am. Chem. Sot. 89 (1967) 30. ’
.
A.!Z. Bcckingham and P.r..Stephens, Ann. Rev. Phys. .Che&. 17 (1966) 399. 1121P.N. Schatz and A.J. McCaffery; Quart. Rev. 23 (1969) -552. : [13] V. Skala. J; Hlavaty and J. K+-k, Collection Ciech. .- Ckem: Commun. 35 (1970) 350: [14] .G.M. Bennnktt and R.L. Wain, J. Chem. sbc_ (1936) 1108.
'__
:
. .
..
Received 28 May 1974
I.
I
:'
'.
The hC'btp&traof phIoro$ucin,
1,3,5-trimelhoxyb2nzene, 1,3,5-trkyanobenzeoe, .13_5+rinitrobenzene,~ 1,3Jbenz’enetricarboxylic acid and 1,3,j‘..benzenctriolrbonyl chloride were measured. For the E' + ‘A;’ transition of phioroglucin or 1,3,5-tricyano~e’tlzene,and the ‘E’ t ‘A’ tknsitidn of 1,3,5_trin:e~oxybenzsne, the FaredayA term was observed and the&D&&e was esfnctcd_ However, 1,3,S-~~~obe~ene, 1,3~S-ben~ene~~~ho~ylic acid and 1,3,.5benzenetricarbonyl chloride showed no magnetic circular dichroism’ inthis spectral region. Themagnetic moments in the ‘E’ states of tbe!:e molecules. seem-to be quenched by the effect:; of substituents. The magnetic moments in the ‘E’ states of benzene derivatives are sensitive to substitution in the benzene ring. f
:
‘,
Magnetic cir&lar dichroism (MCD) has,been used. for the ~vestigation of electronic ~tructur~:s of or- .’ : ganic and inorganic compounds and polymers. There, ‘, are many studies which have deaJt with the magnetic circular dic~ojsm of benzenoid [l-g] and non,, I benzenoid [7-P] aromatic hydrocarbons.,’ .. ” Fecently we have reported the MCD SpCCtKi of. I I hexachlcro-, 1;3;5-trichlaro-, hexabromo- and ” II. I I : 1;3,5’-tribromobenzenes [lo], and extracted the : magnetic moment in the lElu state for each of these corripounds:,Herk we report and discuss the MCD .’ ., ~ectra’of,p~lorogluc~, 1;3,5-t~ethoxybe~zene, 1,3,.55-tricyanobenzene, 1,3,5_trinitrobenzkne; 1;3,5- ‘. ‘. Fig. 1. The lowest sin&et states of the be&ems dtrivat&. Solid and dashed vertiul lines denote the~$lowrd_and forbenzenetricarboxylic acid and 1,3$benzenefricarbidden transitions; iespectively. .’ bony1 chloride. The main purpose of t&s.work is’to : 1, ,. obtain the magnetic moment of the 1E’ state and in- 1) of,l3,5.trimetho’xybenzene, 1,3,5-benzeneformation about the effect of substitution in the. ,: :: t&&ions benzene ring onthe sign and ma~nit~de’?f the mag- 1 tri&rboxylic acid and. 1,3,5benzenet%ubonyIJ chlon&c mcnient in the IE’ state: ,’ ’ ride.may,be discussed by.as.sum&g that these moIe: symmetry. The singlet eIectronic states Accordmgto theoretica! considerations [11, i2], ,’ ,. cules ha&&, when either the ground or the excited state of a corn- .,: ‘, qrising ‘from onk-eIectron excitati;in from .tbe b&best ‘o&pied orb&Is to the lowest vacant orb%& are pound is degenerate, .the Faraday A’ferrri should be .’ observed. The degeneracy of the ground state causes ‘. g&n in. fig. j..In D&, and C3h symmetry; the 1El, k.the Faraday .C term. The Faraday B term arises from.. ’ ..’ IA- transition of’betiene tirresponds to the lF’-* -the mixing of the ~av~fun~~~~.ns’of ~he.groun~ an+ ., : ?A’;gand.l E’ + 1A’ t~ans~~io~, respectiireIyy, and .excited states withthose of bther ele+mi~ states by’ .. ‘Faraday A &ms can be expected for these electronic the’external magnetic field. The n:elec@od ‘systems of .‘.:,.., Jrahsirions. .,: ” 1,3,5-ben- . : ~~0~0~1~~~; 1,3,5~~~~~~~~~ene and ~;3,5-tri@o~’ ._! P~?rogl~~~,. 1,3 ,&methoqbenz+zene, 1 ,+%,.S-trinitrobenzene were benzene belong, to the_po&?t group, D,,.’ The ?rA, nt ‘1 : : ,.z&etrioarbo&lic aiid and . ; :. .‘. .. .. ,.:
.’ -, :.. ‘.
.: !, ,. /. . .. “. : :“, .: .s _.., .. : :: _ ‘... -’ “” : -:, .___. _, ; -.:. :_; _._,;:_:. .. . _,_ .::,- _ ,. .. .. . .I ,, ;._.’ :,.:, . . _: ‘, ._.‘._ : _‘. :, _ _..‘ ...-. .“ ., ;.. ., ,‘,, :: ., :.‘_.‘-.~I _. ., .-, : .’ :h. .’ ; ~.,.,,,, ,‘.: .” ,. ., : :s ,, ;_
: ‘.
_ . .._ _; ,, -: ,. : ., ,, , .’
197’ : ,_,“.;
.-
‘,
_,
:
,,.
._
LETERS.
CHEhf+AL~Pi+IC$ ~y&28,.hyrl& 2 .I, _, ._ . ..,:.L,. ; ., .‘, :’ ., _, &&eicidyQbtain& and ‘@b&l& b’$ rec&fa]la_ : :
,:
:ticirifrc&i water, ~t~a~ol,~~~t~r, and’e*anol, respf+- ’ iti~ely,andIinally dried ,in.vacu& On the tither hand, .. .’ :.!;3,5-b,eniknet~icarbonyl chloridi afid ‘1,3,5;tricyano’ :. be&ne,i~&e prepared’&ti~1,3,5-bertzerietricarb’oxI :.; yli&&d according to the probedtire offetied.by Skala : .‘~i~a~.~[~.~J and Bennett’etal. [14]: Thc’MCD and .’ ‘:. ,‘W spec&a w&e m&&&d &a‘JASCO J-20A reco;d: ) ing spg&opolarirrieter equipped with‘a 12S’kG elec‘tr&tiagnet and 9,n.a Hitachi~EfS-3T recording spectr~~hotom~t~r, respectively, at ioom temperature. .In figs. 2Gthe MCri (A) and UV (B).spectraof __ .‘&Ioroglucin, Id,s-trirr;et~qxyt;en~ene, I ,3,5-t&: %n6benz& anh 1,3;5&i&robenzenk ace &wn; In. ~e-~~~r-w~ven~be~ region, <4Si54) X lo3 ci7’, phlorogl@; 1,3,5-$imet.lq$Eenzene and 1,3,5-t&. .,
‘,._,
.‘
:.
:
,...
; ., ’
:
_
‘. 15 September 1974
.’
,.
..
_-
.
ICll JCllC
.’
‘.
‘. .-
‘-I-..
I..
-t-,
..
. . ‘,
1,
I I ..
‘.
:. ..‘.
‘, @!I %a!e
,_ :: right -5dr
Fig. 3. M&(A) aid I_Jv(Bj ~~peC.tia Of i,3~-t~i1WthO?W benzer,e in ti-hepiane %+&on at roorp temperature,
:
‘.
:’
I’ :. : !.‘_
.IE!,+ l&A;.or IE + IA’ knsition. and the inflection’ point of each A term coincides with ‘the absorption :maxiriun Within the hit pf ex~er~ent~ error. iithe MCD and absorption spectra of i,3,%tricyanobeni zene Tye C&-Jobserve fini kucture which is considered-, .. to be iibr&ic $ruct~re~due to the tqta.Uy symmetric ‘. .: vihratidns. For 1,,3,5-berizenetri~ibo~~~c acid;!,3,5be~~net~~bony~ chloride and- 1,3’,5$nnitiobenzene, no .m&etic’circular dichroi& was obietied’in thissp&itraI re&in. The mq$kic m&&nts in the IE’. states of these c?otipdqndsseemed to be Quenched.
Volume 2,8, ntiber.2.
.,
..
I.5 Septen-,ber 1974
CHEMICAL @HYSICS LETkERS ..
Fig. 4. MCD(A) and U%‘(B) spectra of i,3,%ricyanabenzene at room temperature. As solvents, acetonitiile and acetoniWile-water (1:4 in volume) were used in ihe region of : (31-45.5) X103 cm-’ and (45.5-54) X103 cm-‘, .‘. respdctively.
Fig. 5. MCD(A) md W(g) +ectra of 1.3~~t&itmbexxne at room temperature. As solvents, ethanol-rr-heptane (I:9 in . volume), ethanol-n-heptani (1~24 in voiume) and n-heptznc’ were used in theregion of (24-31) X IO3 cm-t, (31-36~3) X lo3 cm-l.and (36.3-51) X lo3 cm-‘, respectiveI>-.
.’ chroism in this spectral region, which is similar to the 34 X IO3 cm-l. The latter tmnsition indicated case of halogenobenzenes..[ 101. The asSignment of posirivo magkic circuk~ dichroism &$.I& no MCD these tra,n&tion bands in benzene and its deriiiatiies .. band occurs in the former region. Probably the n + was’discussed in our previous paper.’ [I 01. :. rr* transitions of carbonyl groups in 1,3$benzenoFor 1,3,5-trirrrethoxybenzene, 1,3,5-irlcyanobentricarboxylic acid and 1,35_b~nzenetricarbonyl zene and 1,3,5-benzenetiicarbonyl chloride, the corn-’ .’ chloride may be overlapped with the rr +=rr* trarzjiplieated MCD bands, which can’be assigned to the. l&f tions df the berkeile ring which will be stronger than. ‘Ai .-and, I’A’ + 1 A’ symketj-forbidden tranr the nr, 7r+ transitions.~ sitions, appeared in the lowest wavenumber region, The sign and magnitude of the magnetic moment .(3 l-41) X lo3 cm-.I , with the .i - sign, alternations;, while phloroglucin and 1,315benzenetricarboxyk ‘:’ ’ in the excited &ctronic.&ate can be discussed through t&k A/D value_where D is the dipote strength. FG~ the ; acid simply indicated negative and positt/e_magnetic circubu dichroism, respectively,in thik region; For ,. ‘.. :‘E’.& 1Ai .trar&ions of pfilorogIucin and 1,3,5-tri- ’ ’ cyannbbetiene and the lEr + IA’ transition’of 1,j,5-tdnitrobenzene;~the n * rr* transition was obl we obtained A/D and. tirved iri the region of (24-315) X 1‘03 cm-r’ and : .’ !;3 ,Strime@xybenxene, : B/D vah~s by the use of t&e’.method of moments the lowest B ;‘rr* .transition of the benzene ring .: a?$ u;M spectra. As Ferns to corre@ond to the shoulder at ‘:: : ,: ‘:‘.C[12] iprom .”+Jledbs&ved~MCD ,;. about ‘_ ..’ ,. .,: c ., ‘. ,’_::; -..,.._ :. ; : ., ‘. .. ; ‘, 199 ,:. .’ . ‘z.
z
Ex&ed,Faradai p,arame!ers,-for tht ‘J$+ irid D.6h’symme.~y,-respectiveiy .,,
Table 1 : .I ‘.. ... 'A', ‘i; + ‘A’, .and !EIU ‘- ‘,I; g tiqnsitiqns of benzene derivatives with Csh, D3h,
. v x ICI-~ (m-l)
phloldglucin’ 1~;5-trimetlloxyb.enzene 1,3,5-tricyanobe&h&: 1,3,5-trichlorobenten-a) 1,3,5-tribromobenzene”) .‘hexachIorobenzenea) hexabromobenzene a)
’
., .,
-,
‘.
:
49.7 49.2 48.0. 49.6 48.2 -46.4 44.2
_, d;b (p)’ -.
::_ : ‘, ‘.
0.323 0.301 ‘.. 0.182 0.207
:
:
‘.
.a).Froh-‘;ef..
;
‘-
-, .,_
-1.29 2.49 -2.35 -5.79
,0.172
I_ ‘.
i?/D’X,105 lj&rr’)
0.127 0.262
:
y
-.
:
-7.W : -1.98 -4.45
. .
[lo].
‘. -.
shotiii in table 1, the A/b values pf these molecules tire in agteemerit with those of halogetiobenzenes ” [lo] both in sfgn‘and ordei of magnitude. In the case of 1;3,5_trinitrobenz?ne, 1,3,5-benzenetiicarboxylic acid tid 1,3,.5-benzetietricarhonyl chldride, ‘:the magnetic moment is so small that no magnetic ~circ& dichroism wzs observed in the higher wavc“num!e;-regiqn:The magnetic moments in the 1E’ ‘states of benzene derivatives are sensitive i0 the effects .:,of substituents. EqIoration of these. e&per&mental residts di the SCF MO method is now under investigaiion;:_,‘._
_-
‘,
.:. :
;. -. ’ Riferims
[;I DJ. Shieh, S.H. Lin and H. Eyring,Proc. ki. US.69 (1972) 2000. [4] D.J. Caldwell and H. Eyring, J/&em.
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1149:
[5], D.J. Shieh, S.H. Lin and H: Eyrk,
J. Phys. Chcm. 77 (1973) 1031. [6] 1.X. Doug& R. Grinter and A.J. Thomson, Mol. Phy;. 26 (1973) 1257. [7] A:Tajiri’and hf. Hatano, Bull. Chem. Sot. Japan $5 (1972) 952.’ ‘[B] H ..Uchimura, A: Tajiri and M. Hatano, Chem. Phys.
LMfPCS 19 (1973) 513. (91 A. Tajiri and Ml Hatano, Chem. Phys. ietters
25 (1974) 5f,6. [lO]‘A. Kaito, A. Tajti and M. Hatano, Chem. Phys. Letters
25 11974)54s. [ll]
-.
-. [I] P.J. Stephens, P.N. Schatz, AD. Ritchie and A.J. M,cCaffcry, !. Chcm.?hys 48 (1968) 132. [2] J.G. Foss and h1.E. M&ar~lle;-J., Am. Chem. Sot. 89 (1967) 30. ’
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A.!Z. Bcckingham and P.r..Stephens, Ann. Rev. Phys. .Che&. 17 (1966) 399. 1121P.N. Schatz and A.J. McCaffery; Quart. Rev. 23 (1969) -552. : [13] V. Skala. J; Hlavaty and J. K+-k, Collection Ciech. .- Ckem: Commun. 35 (1970) 350: [14] .G.M. Bennnktt and R.L. Wain, J. Chem. sbc_ (1936) 1108.