41eReports01'cheKanazavv
et1Jni可ersity，Vol.VI，No.1，pp.，11‑
4'
1，Aprii，1
958TheSci
cD.c
Onthe MagneiicSusceptibilityof Pyridine
By，oR
UHA ar:d Matsuo TERAKURA
Juro IVL(Receiv
edFebru
ary6，1958):lyexp色rimen
Manyworkers have made physico..chemicals
tudiesofpyridi色合， notor】

tally，buttll号asithasespeciall
ysimilarstructur
eto benzene. Consequently，theor
eticaltalr
esult
s of
were introduceds
uccessfull
y about experim巴n.
iol告tsp邑ctra，ultrav

rnoments，bond. distances，etc.，ofpyridine.
h抗告1・0ωatoms in the conjuga士宮d system，it1
S important

On rnoJeculesi.
J呂t v
alu号s yv‑ew:of the Coulomb int己gr呂 1(α) of nitrogen atom andthe ex.

(s) ofcarbon‑nitr
刊 en，whenthey are calculated by meanso
ftheLCAO‑MO method. The calculation hadbeen done frequently using the correctedvalu行司 αN=αc十b川 町 cent work sugg邑St
5 thatαc十 0.
5/3is arat
her mor日 likelyvalue.
CJ‑)Andt
he results donot50di宣告 rfrom thoseby thesimple M O methodusing+0.5s，even if:111ecale叫 ationswo叫 dbe madetose1
f consist告は by a process of。

i1.

rge
let a1.(2) adopted following parameters，whensuc.
ce
SSlve

moments of as
邑riesof conjugated heterocyclic compounds，

they cornputed
は(C)=6;， α(-N~)=α }_.ßJ α(C ト N))=α +O.lß ， {3cc‑C)=孔 and sCC‑‑N)=1.2
s.lt gave verygood
1.
1ction of a h抗告 ro‑atom，of course，must
The introdresults about suchtoth色 Coulomb integral and th忠 由[change integr
al，and the.
1t
abo1above choice of param居t
e1'si
smore adεquate in comparison with the calculation
the correct
io:nt
onitro疋en 品tomonly.
On the other3)oF.London gave a theory(fmagnetic suscept
ibil
ities dl.
le tostos
呂y，rnaglletic susceptibilities due toπ‑electrons in aromatic compounds，that iield applies perpendicularly tomolecuJgr orbitalsofn‑el記ctrons，when a 1γwgnetic f
C
4
1‑
1.Brooks
ftheoverlap
コ consid日rεd a influence oan<に andt
h邑 molecular 1)lstheconsequencetheyobtainedverysuitableatoms，and aresults about
We havemeasurements ofmagnetics
usce
pt
i
bi
l
i
t
i
e
sabouttwocomponentsyst告msofsubstances8110
has pyridine‑wat飢， pyrio.
ine‑
acet
i
c acid，etc，圃 andstudied the interact
ion between t
11e two on邑s. As we needed to carry out thenaccordancewiththesuscept
ibil
ity du巴 toπ‑electron，we，icalculation ofm抗 hod 0
1 London，calculated using param日tersse
l邑cted by Orgel and obtained
reasonab.
Je vall.
les.
Iia

長
官1<1 (的secular色qu
at
iolli
s

is

perpendicularlyt
othemolecularplane，London's

theexchangei
ntegr
al{
3beingunity，bya干ollowingequation，

42工島fARUHAand M. TERAKURA
7Jkel

where X=(E α)js and1=←z)‑Xdk11=0，c;i‑H1l‑X1Yk);

L̲

(1)
Ii
s amagneticfluxpassingr
iginarbitr
arily
throughthe triangl
e form記 dbythe neighbouringatomsム1 andtheo
chosen in the plane ofthe molecule.

1isKron号cker'sdeltaand7
Jklequalst
ounity，

when 1neighbourswithk，otherwise zero・Inthiswork，howev日r，we adoptth邑 parametersofOrgel in the equation (1)，th邑n
we canwrite explicitlythefollowing form
‑X+l 1
1.2ε1栄 一 X+O.l

1.2ε6持ε2‑x1:3発1.2
where ε叩汁εs‑Xεε4*(2)=0‑X"
58‑X+O.l
5於1) and εfニ exp(‑2rrif町 汁1)' Expanding く2) and aft
er someapproximations，we obtain(3)
F(X)十 1.
44(2π/ア=0.
F(X) equals to a equation introduced
simple LCAO‑MO，in other words，itcorrespondsto the equ呂 tionputting s=ε 先 =1. Th告 refore，considering the symm邑trygroup ofthe pyridine molecule(C2V)，vye cansolv官 inthe following factors，X2̲.0.1X‑l=O(4)(4/)
X ‑LIX3‑5.78X2+5.56=0
十 3.2X会ortheoccupiedlev
elsi
sshown in Table LEach root X1 fIffi
ssmallerthan1，th巴 rooto
fthe問 uation (3) is approximately
ノトx=X

inwhichX"=‑L44jP'(Xうπ，isthe firstderivativeo
fF(X) The value of X"ーisa1so given in Table LNow，the diamagnetism due toelectronso
f the occupied levelswasexpressed byLondon as th色 followingform，
Table 1P
yr
idine

ごたよ 0.0555に+1.67309

1，calculatedwithαN=αc+2戸.
ll，calu
cu
late
dwit
hαN=αc十 0.5s，
調 cal
旧 日late
dwit
hO
r
ge
l'
spar
ameters.

土ニーニ.
04
753:
一二， 05391

Sum43OntheM 勾 neticSuscettibili
えY ザ Pyri・dine{2πeSi22記 χ cup= -4'呂(X")xIWJltヲ'c~ ) ，叫

where WJ keeps almost a equal value for benzene and pyridine，andS indi
cates
the areaoftheconjugateds
ystem.Thereforethesummationo
fX"wouldbecompared，together with thosewitht
hatofbenzene.The valueso
fitar
e shown in Table1ofbenzene.Thevaluescomputedwitht
he Coulomb integralof nitro~en atomusingrealso given in Table1. Theresul
tusingα+0.5s doe
snot
α+0.5s，and α+2s，a's para.
meters，but the other ont'! appears
appreciably differ from that of Orgelo
unacceptable.S i
scomputedusingcarboncarbond
ist
ance，1.39A，andcarbonnitrogen。
dist
ance，1.3
7
A. ThenSpyjSbenz =0.
988. Therat
ioof罰 (X") is0.
971.Consequently
四司t:.Kpyj
t:.Kb z =0.948，inwhich t
het:
.K i
s the ma伊 eti
c contribution owing to the回5) we on‑electronor
bitals.I
f we adoptt:.Kbenz =‑54x1
0‑6 c
gS.，
(btain!
:J.Kpy = ‑
52.
4x

10
‑6 cgs
.
A measurement of magnetic anisotropy ofpyridineis not yet made，but the(6)andourobservedg
ram‑susceptibilitymagnetics
usceptibilityismeasuredrepeatedly，"'J.
gi
s ‑0.610x1
0ー
へ sothemoleculars
uscept
ibi
lit
yX
Mol
=‑48.3x1
0‑6 cgs.，
whichagrees

renc
h's.
withM.F
Onthe ot
herhandthemoleculars
usceptibilityinduding conjugateddoublebondsiscalculateda
ddi
tiv
el
ya
sf
ol
lows，
X
Mol
=
LJX
Atom十 t:.Kj3，inwhichX
Atomi
satomic increment.For pyridine，

2
JX.
i¥.t
四 =5Xc‑c=)+5XCH‑)+χC‑N‑)・
Hereweadopt thefollowing values，
C7コχC‑c‑)=ー 3.36x1
O‑6cgs.andXCH‑)=‑2.93x1
0‑6cgs.
Previous workers，however，did not determine the values ofXC‑N=)，whichwecan
now determinedfromthe abovementionedvaluest
obeχト N=)=O.
f ‑CH= group in hydrocarbon
This is very interestingresult，showing that icontaining cojugated double bond is replaced by ‑ N= group，the molecular.e.，‑6.29x10‑6suscept
ibilityonly decr
easesbythe valuecorrespondingto ‑CH=，icgs.，under t
he condition of neglecting the change of the molecular orbital byn‑electr
ons，asithasonlyl
itt
lei
nf
luence.We haveafewcaset
oexaminetheabovef
act，butthefollowingcompounds，whose valueswere determinedinour laboratory
¥￨/引い

09N
ヨ八lvN ゆryfy¥/¥〆〆￨¥一regoodexamplesto confirmt
hesecircu
mstances.
andweregivenbelow，a‑91.82
χMol X1
0scgs.
Thusthemagnitudeo
fthemagnetic suscept
ibi
lityo
feach substance decr
ease
s by
4X1
0‑6 cgs.，progr
essiv
ely.Thisvaluej
ustcorrespondst
ot
he above conclu
s
ion.
‑6.

S由i:J.
.
mary
We tr
eate
dthemagnetic anisotropyo
fpyridinebymeanso
fLondon'stheory. InJ.MARUHA and M. TER.AKURA

44this paper，w配 adoptedα+sandα+0.

as the COU101叫hatom andthat ofthe carbon atomand ，12(3 as exchange integral between carbon

111thi
scase weobtained0.971 asthe value ofthe ratioof theto that ofbenzene. Whenα+0.5βwasused asthe Coulomb integr
al oftheatom，theresul
twasrathersmall.
Andit became evident t
hat ther巴oftheatom into aromatichydrocarbons {;[ave no atomic iucrement ofthe diamagnetism.

The autherswisht
o expr巴sstoaclmowledg告 ourmura forhi
sencouragement

toProfessor T.Tono‑thiswork.
Rei
官民阻む倒(1J C.A.Coulson， Valence"，(OxfordUn
iversityP
ress，1952)，p.2
42.
(2J L.E.O
rgel，T園L.Cottreli，TN.D
ickandL.E.Sutton，Trans.FaradaySoc.4
1，113(1日51)圃

[3J F.London，].dePhys.8，397(1937)[4J H.Brooks，J.Chem.Phys.9，463(1941).
'
仁 S.Krishnan，B.C.GuhaandS.B
aner
jee，PhiLTrans.2，:nA，235(1933).
[5J l[6J M.French，TransF
araa邑ySoc 向 ~7 ， 1056(1自51)，Shib
呂 andG.Hazato，Bul
LChem.Soc， }apan22，92(1949)
.
[7J H
刷

[8J J
.M
aruha，readbeforeth
e10thAnnualMe巴tin
goftheChem.SocJ
apan，Apγ，!
i (195'7).