Acta C/~-"ciaIndica. Vol. XIllP.,No. 1. 6 (/987)
, 1HYlJh: Ill]!;::.> uN ~;Lb:C'I'li:uNb.;(~A'1' J Y 1 'l'Y
VIRENDRA KUMAR JAINAND
Z. H. ZAIDIDEl-'AkTl1EN'l' uJ-t' IJH Y!3 1 C::':;
JAMIA MILLIA [~LAMIAJAMIA NAGAR. NEW DELHl-l1UU~~
INDlA.
Received: 26 May,
The empl r-LoaI reJClLion
proposed by us r 1 I has bef-!Il extended Lo
calculaLe. vilJratiowd ~l e for(HnLO/lli(~ hvdr i de s . x~ , xfl and nfl' »» are Lhf:'
elf!ctre,negati vi ties and the number of va l errc e
el(,~ctru!J~; .fir constituent atoms A and B
r~s~ectively. K is a constant for each group or
subgroup ofi~he periodic table and f. is the. .
reduced mass o~ the molecule AB. The results
obtained .usi rIg the new relation are in better
agreement w i Lh the experimental va l.ue s than
Lho::-;e 0/>1,;1 i Jlf:!d f:!ar1i er by Huxaa i r, f? r .
t', .'{:> f.,.. '_0 .
2
A number of worKers r3-6] have shown that ~he/
reduced mass f and the electronegativity may play dn
important role in the calculation of vLbrat.Lona I constant tI)e/
of· diatomic molecules. Krasnov and Maksimov [7] pointed
out that exact dependence_of We on the reduced mass, must
take into account the type of chemical binding between
the constituent atoms of the molecule. However, the
relation suggested by them do~s not appe~r to contain any
molecular parameter which could b~ said to depend upon
chemical binding.
It has been ~hown th~t the vibrational frequencyof a diatomic hydride A-H should have a linear relationship·
with the electronegativity of A [8,9,lU]. This deductiun is
obvious from the fact that during the vibration of a
hydride molecule, displacement of the hydn.J~F;n wOlll.d in
turn cause a displacement of the valence e Lect.rons in the
potential field of the heavier atom. In a vibrat.o ry 1.ink
A~H , both A and H are displaced with respect to the centre
of gravity of the bonding electron cloud. Gordy allll
Thomas [llJ concluded from this, that in a diatomic
moleculeWt! = f ,( x A . x (3) _.r--: - - •• - - - - - - •• - - - - - - - - ( 1)
where f ( Xftxf3 ) is a function of the product xfl xfJ.,
3
Recently, the present authors suggested that the
valence electrons should also .be taken into account while
considering the nature 'of/chemical bonding in between the
consti tuent atoms and We Sh~d be taken as a function of
the product of the electronegativities and the number of
valence electrons of the constituent atoms. The suggested
relation was
We = K ( x t1. n[y x[3 nR ) /Jf --------(2)
where K was a constant for each group or subgroup of the
perLod Lc table', n A' nf3 were, the number of valence electrons
associated with atoms A and. B respectively. We call the
product ~A .nf3 as the "Valence Force" acting between atom
A and valence electrons nB The relation gave fairly good
agreement with the observed values whe'n used to calculate
~'e for diatom~c oxides.Ln an attempt to see the validity of relation (2)
for other molecules, we ,have applied it to compute the
values of We for diatomic hydrides. The resGlts which
are in better agreement with the experimental values as
compared to earlier work, are being reported in the present
note.
The calculated Mld experimental values wherever
available, are compared in Table -1. The ,values of I ,. for'-Vet
some diatomic' hydrides which have not been,)
studied
e~periment~lly so far, are predicted. It is clear fromI
TKbl-=:-1 t.lt~1t the ;';H?reement t·'~tween t.,hf.~ values of W observe.Ie.
4
TA,i?J.kL COMPARISON OF OBSERVED AND QALC!l1AIEP. Yl~RAIIONA1---'-GQN~iiMrl?-'(t-C-iiii-gID-11-'- -- -_._- '------------------------------------~-----------------------~-~--~-Group~
'. ~ Q~lgy!~t~g" Q~§~~y~gbaEE~Q~~~ K~~Ql,Molecule Electro- Authors Hussain or Authors Huasaan
-negativity estimated--------------------------~---------------------------------------------------_.HH 2.1
LiH 1.0 1405.65 1412 14D5.65 0 -litI A NaH 0.85 1141. 48 1160 1172.2 +3 +1(1) KH 0.74 985.16 1014 983.6 0' -3
K=628.35 RbH 0.7 925.53 936.7 936.9 +1 0CsH 0.69 910.38 872.0 891. 2 -2 +2
BeH 1.6 2058.6 2036 2058.6 0 +1II A '.MgH 1.2' 1494.69 1496 1497.0 0 0,,(2) .CaH 1.06 1309.63 1221 1299.0 -1 +6
K~291. 66 SrH 0.98 1202.64 1201 1206.2 0 0BaH 0.97 1187.92 1172 1168.31 -2 0
BH 2.0 2248.96 2617 2366.9 +5 -11III A AIH 1.5 1644.32 1683 1682.56 +2 o '~
(3 j GaH 1.48 1604.52 1775 1604.52 0 -11K=17151 InH 1.36 1470.17 1545 1476.0 +1/2 -5
TlH 1.34 1445.78 1532 1390.7 -4 -10
CH 2.6 2859.1 2862 2859.1 0 0IV A SiH 1.9 2042.60 1966 2041.8 0 +4
(4) GeH 1.8 1914.43 1825 1908 -1/2 +4K=126.23 SnH 1.6 1696.99 1750 1715 +1 -2
PbH 1.5 158e.13 1641 1564.1 -2 -5
NH 3.0 3203.2 3300 3203.2 0 -3V A PH 2.2 2305.40 2107 [2380]1 +3 +12( 5 ) AsH 2.0 2076.36 1925 [2037 ]ei -2 +6
:# K=98.60 SbH 1.8 1864.00 1804 [1866] 0 +3BiH 1.7 1757.38 1698 1698.9 -6 0
OH 3.5 3739.94 3735 3739.94 0 0VI A SH 2.53 2663.10 2700 2689.6 +1 0
(6) SeH 2.3 2398.71 2481 [2400)l 0 -3K=82.58 TeH 2.0 2080.83 2194 [2073] -1/2' -6
FH 4.0 4032.17 4243 4138.32 +3 -3VII A CIH "3.0 2989.14 2990 2990.94 0 o \,
(7 ) BrH 2.68 2648.98 2635 2648.98 0 +1/2K=67.09 IH 2.36 2327.47 2309 2308.09 -1 0
AtH 2.2 2166.11 2009 [2138]cl -1 +6
TABLE-1 : .continued......IS
VIII NiH' 1.8 2000 2000 0 -(10) f'dH 2.0 2213.36 -K=52.66 f'tH 2.1 2319.2'1 r2293.6JC -1
I B CuH 2.0 1940.4 1940 1940.4 0 0(11 ) AgH 1.8 1'r40.69 1826 Ho9.9 +1 -4K=41.83 AuH 2.4 2315.96 2305 230b.01 -1/2 0II B ZnH 1.7 Hi07.6 1608 1607.6 0 0(12 ) CdH 1.5 1413.63 1433 1430.7 +1 0K=37.38 HgH 1.5 1410.93 138'1 '1387.09 -2 0
----------------------------------------------------------------------------~*-Numbers within parentheses are the number of valence electrons and K 1s a,..
constant for each group. -a-Collected from Pritchard and Skinner, Chem.Revs., 55, '145 (1955); Gordy and
. Thomas. J.Chem.Phys .. 24, 439 (1956); Allred and Rochow, J.Inorg.Nucl.Chem.5, 264 (1958); Mulliken, J.Chim.Phys. 46. 497 (1949)
b-Taken from American Institute of Physics Handb00k, McGraw Hill Book Co ..Third edition (1982) and Huber and Herzberg, Molecular Spectra andMolecular Structure IV. Constants of Diatomic Molecules, Van Nostrand Co.Newyork (1978),if not indicated otherwise.
c-Values are uncertain.d·.Values estimated by Sheline (1950) and Varshni (1958)
and those calculated with relation-(2) is better. in general,
than the previous calculations made by Hussain [2]. The maximum
deviations between the 9alculated and experimental values
are about 6% for BH and BiH. Spectra for these molecules have notbeen studied in absorption [12] and if the observations are made
only from studies in emission, one cannot be completelysure whether. the observed values represent those of the ground
...state or not. Values of UJe predicted from relation (2) for the
molecules AsH. SbH, TeH and AtH are in good agreement with
the values estimated from the force constants obtained by
Sheline [13] and Varshni [14].
REFERENCES
[1] Jain, V.K.;Mishra,A.K.and Zaidi,Z.H.;Acta Ciencia Indica 12 •.80(1986 ).
[2] Hussain, Z.; Can. J. Phys. 44, 917 (1966).[3] Hussain, Z.; Can. J. PHys. 43, 1690 (1965).[4] Goodfriend, P.L.; Can. J. Phys. 45,3425 (1967).[5] Singh,S.P. and Mathur,V.K.;Indfan J. Pure Appl. Phys.
I
1·: '6,38'6.(1968).- \. .
[6] Sharma,K.K. and Hussain,Z.; Indian J. Pure Appl.·Phys,'.7,662 <,1~89-\ .
[7] Krasnov, K.S. and Maksimov, A. I.; Optika Spektrosk; 8,403 (fs.e0).[8] Pauling,L.; The Nature of the Chemical Bond, Cornell univerSi~
.Press, Ithaca,New York; 58\75 (1939~[9] Walsh, A.D.; Proc. Roy. Soc. 207 A, 13 (1951).
[10] Wilmshurst, J.K ..; J. Chem. Phys. 28,733 (1958).[11] Gordy, W. and Thomas, W.J .0.; J. Chem. Phys. 24, 439 (1956). '-..
![12] Herzberg,G.;Spectra of Diatomic Molecules;D.Van Nostrand Co.Inc.(1950).
[13] Sheline, R.K.; J. Chem. Phys. 18, 927 (1950).[1.] V~shni, Y.P.; J.Chem. Phys. 28, 1081 (1958).
tI