J. Phys. Chem. 1992,96, 1087-1095
The CID results agree favorably with other results in all cases. Duncan et al." have recently determined a value of slightly less than 2 eV for the upper limit of the silver-benzene bond dissociation energy, in reasonable agreement with the results of this study. Ion/molecule reaction rates derived similarly to earlier method010gy~~ for the various reactions resulting in metal-metal bond cleavage are listed in Table V. All values are less than that predicted for an ion-induced dipole orbiting " L ~ n g e v icollision. n~~ As discussed previously,16 this observation suggests that charge transfer is not occurring via a long-range electron jump mechanism and thus that adiabatic rather than vertical ionization potentials are indeed being determined. COnClUSiOM
Charge-transfer bracketing has proven to be a useful method for determining ionization potentials of highly reactive species such as metal and semiconductor clusters. Bracketing may also be (41) Duncan, M. J . Phys. Chem. 1990, 94,4769. (42) Langevin, P. M. Ann. Chim. Phys. 1905, 5, 245. Translated in: McDaniel, E. W. Collision Phenomena in Ionized Gases; Wiley: New York, 1964; Appendix 11. (43) Lias, S.G.; Bartmess, J. E.; Liebman, J. F.; Holmes, J. L.; Levin, R. D.: Mallard. W. G. J. Phvs. Chem. Ref. Data 1988. 17. ISUDDI. No. 1). .(44)Moini, M.; Eyler, 3. R. Chem. i h y s . Lett. 19k7, ij7, j i l . (45) LaiHing, K.; Cheng, P. Y.; Duncan, M. A. Z . Phys. D At., Mol. Clusters 1989, 13, 161. (46)Cheng, P. Y.; Duncan, M.A. Chem. Phys. Lett. 1988, 341. (47) Cheng, P. Y. Dissertation, University of Georgia, 1990. (48) Powers, D. E.; Hansen, S.G.; Geusic, M. E.; Michalopoulos, D. L.; Smalley, R. E. J. Chem. Phys. 1983, 78, 2866.
1087
applied to determine other physical properties such as proton and electron affinities of metal clusters. Although direct laser desorption/ionization methods such as those used in this work are limited to the production of relatively small cluster ions, clusters as large as five atoms may be studied effectively. Metal oxide mixtures have been utilized to produce high yields of mixed-metal clusters by varying the characteristics of the vaporization laser and the oxide mixtures. The ionization potentials determined by the CTA bracketing method show good agreement with the few well-known values for these species, indicating a high degree of accuracy for this method. The presence of side reactions in addition to charge-transfer reactions causes difficulties in the acquisition and interpretation of the charge-transfer results. However, detailed study of these reactions may prove useful in studying the dynamics of adsorption onto metal surfaces as it relates to heterogeneous catalysis.
Acknowledgment. This research was supported by The Office of Naval Research. We thank Professor W. Weltner for the use of several metal samples and Dr. K. R. Williams for numerous helpful comments. Registry NO. Ag2, 12187-06-3; Ag3, 12595-26-5; Ag5, 64475-46-3; , Au~,12187-09-6;A~3,75024-07-6;Au~,131359-45-0;C U ~12190-70-4; Cui, 66711-03-7; AgCu, 12249-45-5; AgCu2, 52373-99-6; AgZCu, 98002-69-8; ferrocene, 102-54-5; N,N-diethyl-p-toluidine,613-48-9; N,N-dimethyl-p-toluidine, 99-97-8; N,N-diethylaniline, 9 1-66-7; N,Ndimethylaniline, 121-69-7; azulene, 275-51-4; m-toluidine, 108-44-1; aniline, 62-53-3; 2-naphthol, 135-19-3; hexamethylbenzene, 87-85-4; p-dichlorobenzene, 106-46-7; 1,2,4-trichIorobenzene, 120-82-1; m-dichlorobenzene, 541-73-1; fluorobenzene, 462-06-6; benzene, 7 1-43-2; tetrachloroethylene, 127-18-4.
Structural Determlnations for Two Isomeric Forms of N,O-HCN
D.C. Dayton,+ L.C.Pedersen, and R. E.Miller*.$ Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599 (Received: July 15, 1991)
High-resolution infrared spectroscopy has been used in conjunction with molecular beam techniques to identify two isomers of the N,O-HCN binary complex. The more abundant isomer has the two monomer units essentially parallel to one another. The less abundant, and presumably higher energy, isomer is linear with the HCN monomer unit acting as the acid. Isotopic substitution reveals that the hydrogen atom is bonded to the oxygen end of the nitrous oxide subunit. Ab initio calculations have also been armed out for this system, using a number of different basis sets. Comparisons are made between the rotational constants, vibrational frequencies, and relative stabilities of the two isomers.
Since the dimensionality of intermolecular potential energy surfaces increases rapidly with the complexity of the associated monomer units,one expects that the likelihood of there being more than one local minimum on these surfaces would increase in a similar manner. For systems in which the intermolecular interactions are highly anisotropic, as in hydrogen-bonded complexes, the possibility therefore exists for the formation of more than one stable isomeric form. The large anisotropy is important since high barriers are nceded to ensure that the complex can be frozen into the various local "a. A growing number of such systems have recmtly been studied using a variety of spectroscopic methods.'-15 The observation of more than one isomeric form of a complex is important, given that data of this type provide us with infor'Resent addreas: U.S. A m y Ballistic Research Laboratory, SLCBR-151, Aberdeen Proving Ground, M D 21005-5066. *Towhom correspondence should be addressed. *Alfred P. Sloan Fellow.
mation on more than one region of the intermolecular potential. This is particularly significant in molecule-molecule complexes, (1) Joyner, C. H.; Dixon, T. A.; Baiocchi, F. A.; Klemperer, W. J . Chem. Phys. 1981, 74,6550. (2) Lovejoy, C. M.; Nesbitt, D. J. J . Chem. Phys. 1987, 87, 1450. (3) Dayton, D. C.; Miller, R. E. Chem. Phys. Left. 1988, 143, 580. (4) Lovejoy, C. M.; Nesbitt, D. J. J. Chem. Phys. 1989, 90,4671. (5) Kukolich, S.G; Bumgarner, R. E.; Pauley, D. J. Chem. Phys. Lett. 1987, 141, 12. ( 6 ) Kukolich, S.G.; Pauley, D. J. Chem. Phys. 1989, 131, 403. (7) Kukolich, S.G.; Pauley, D. J. J. Chem. Phys. 1989, 90, 3458. (8) Leopold, K. R.;Fraser, G. T.; Klemperer, W. J . Chem. Phys. 1984, 80, 1039. (9) Klots, T. D.; Ruoff, R. S.;Gutowsky, H. S.J. Chem. Phys. 1989,90, 4217. (10) Dayton, D. C.; Pedersen, L. G.; Miller, R. E. J. Chem. Phys. 1990, 93,4560. (1 1) Haynam, C. A.; Brumbaugh, D. V.; Levy, D. H.J. Chem. Phys. 1983, 79,1581; Levy, D. H. J. Chem. Soc., Faraday Trans. 1986,82, 1107. (12) Aldrich, P. D.; Kukolich, S.G.; Campbell, E. J. J. Chem. Phys. 1983, 78. 3521.
0022-3654/92/2096-1087$03.00/00 1992 American Chemical Society
1088 The Journal of Physical Chemistry, Vol. 96, No. 3, 1992
where the intermolecular potential surface is sufficiently complex to prohibit its entire determination from measurements which represent averages over the surface. This is even true for (elastic and/or inelastic) total and differential scattering cross sections, which are normally considered the least averaged of the methods traditionally used to determine these potentials.1619 In contrast, the study of individual isomers of a given binary molecular pair provides us with detailed information on small subsections of the potential surface. Given these test points, it is perhaps not unreasonable to expect that so” form of interpolation between the various regions might be made. For example, ab initio calculations, once tested at the points defined by the characterized isomers, might be used for this purpose. In any case, the philosophy of dissecting the multidimensional potential into manageable pieces seem to be a sound one, which is applicable to any system which can be frozen into more than one of its local minima. Since the hydrogen cyanide molecule can act as both an acid and a base, since the hydrogen atom is electropositive while the lone pair on the nitrogen is electronegative, the associated binary complexes have the potential for existing in more than one isomeric form. Also, since the dipole and quadrupole moments of hydrogen cyanide are large, the interactions between HCN and other molecular species tend to be highly anisotropic, with multiple minima. We have recently reported13 the observation of two isomers (linear and T-shaped) of C2H2-HCN, while both mic r o ~ a v eand ~ . ~infrared’O studies reveal the presence of two isomers for C02-HCN. In the present study, the optothermal method20has been used to record infrared spectra associated with the C-H stretching vibration in three weakly bound species containing both N 2 0 and HCN. Two of these spectra have been assigned to linear and slipped-parallel N20/HCN binary complexes, providing the first structural characterization of these two species.21 Using the rotational constants determined from the present study, Pauley et a1.22have measured the microwave spectrum of the parallel isomer but were unable to detect the less abundant linear form. The third spectrum observed in the present study has been tentatively assigned to a higher order N20/HCN complex, although a detailed structural analysis has not been possible in this case. The linear complex is analogous to the linear isomer of C02-HCN,9J0while the second, parallel structure, has not been observed for C02-HCN, although it has been predicted by ab initio calculations.1° Ab initio calculations have also been carried out for the N20/HCN system, providing some further insights into the nature of the intermolecular potential energy surface.
Dayton et al. Linear ‘“NO-HCN
I
;
32%.60
~
;
;
3297.20
;
;
:
3297.80
$
1
11
:
’
3298.40
’ ’
:
;
3299.00
I
Frequency (cnr3
Figure 1. Rovibrational spectrum associated with the linear I4NN0HCN isomer. The two transitions in the “negative” direction are assigned to the R( 1) I doublets of the 1 l1O4lIOHCN monomer hot band.
TABLE I: Summary of the Molecular C o ” Q for the Linear and Slipped-Parallel 14N20/HCN Binary Complexes Linear I‘NNO-HCN Isomer B‘‘ 0.037420(6) B’ 0.037107 (5) D” 1.89 (30)X D’ 2.59 (20) X YO
A” B”
C” DY DjK” DK”
3297.8200 (5)
Slipped-Parallel ONI4N/HCN Isomer 0.344241 (27) A’ 0.343255 (20) 0.093 793 5 (42) B’ 0.093835 8 (35) 0.0733761 (51) C’ 0.073349 2 (36) 2.36 (58) X IO-’ D,’ 1.56 (31) X lo-’ 1.81 (58) X IOd DjK’ 3.89 (32) X 10” 4.42 (2.67)X IO“ D/ 1.50 (1.40)X 10” YO
3309.4590(5)
“The numbers in parentheses are errors reported as one standard deviation. The errors in the vibrational origins reflect the uncertainties in the HCN monomer transitions used to establish absolute frequency calibration. All values are reported in cm-I.
For the complexes considered here, this change results from the fact that the excited molecules dissociate before reaching the detector. Due to the recoil of the resulting fragments out of the molecular beam, the bolometer detects a laser-induced decrease in the molecular beam energy. For the normal isotopic forms of HCN and N20, the molecular beam was formed by expanding, from a pressure of 260 Wa, a mixture of 12% N 2 0 and 0.9% HCN in helium through a 50“-diameter room-temperature nozzle. Further structural inExperimental Section formation was obtained by measuring spectra of the comsponding The infrared spectra presented in the following sections were W N O complexes. For the linear isomer a mixture of 5% % N O obtained using the optothermal technique, which has been dis(Cambridge Isotope Labs) and 0.5% HCN in helium was used cussed in detail in a number of previous p u b l i c a t i o n ~ . ~ JIn~ J ~ ~ ~at~ a source pressure of 250 kPa, while for the parallel isomer, a brief, the method involves the use of a tunable F-center laser mixture of 4% 15NN0and 0.6% HCN in helium was expanded (operating in the range 2800-4500 cm-’) to vibrationally excited from 200 kPa. In the latter two cases the concentrations and molecules in a well collimated molecular beam. The spectrum pressures were adjusted to give reasonable signals while conseming is observed by monitoring the resulting change in the molecular the amount of 15NN0 needed to record the spectrum. beam energy with a liquid helium cooled bolometer detector.23 R@ultS Linear Isomer. In view of the many similarities between the (13) Block P. A.;Jucks, K. W.; Pedersen, L. G.; Miller, R.E. Chem. Phys. C 0 2 and N 2 0 monomer units and given that a linear, hydro1989,139, 15. gen-bonded form of C02-HCN has already been observed>l0 a (14)Janda, K. C.;Steed, J. M.; Novick, S.E.;Klemperer, W. J. Chem. Phys. 1977,67,5162. linear form of N,O-HCN is obviously expected. The C-H (15)Fraser. G.T.; Pine, A. S.J . Chem. Phys. 1989,91, 637. stretching vibration associated with such a complex will be sig(16)Hirschfelder, J. 0.C ;urtis,C. F.; Bird, R.B.Modern Theory ofGases nificantly red shifted from the monomer band origin2‘ owing to and Liquids; John Wiley and Sons: New York, 1954. its intimate involvement in the formation of the hydrogen bond. (17) Atomic and Molecular Beam Methods; Scoles, G., Ed.; Oxford University Press: Oxford, 1988;Vol. 1, Part 11. Searchw carried out in this region revealed the spectrum shown (18) Toennies, J. P. Ann. Rev. Phys. Chem. 1976,27,225 and references in Figure 1, which is clearly that of a linear (or possibly quatherein. molecule. This spectrum was absent when the N20 (19)Pauley H.; Toennies, J. P. In Advances in Atomic and MolecuLr Physics; 1977;Vol. 13, p 195. (20)Huang, Z . S.;Jucks, K. W.; Miller R. E. J . Chem. Phys. 1986.85, 3338. (21) Dayton, D. C.;Miller, R. E.44th Sympium on Molecular Spec-
troscopy, Paper TF7; Columbus,OH, June 1989. (22)Pauley, D.J.; Roehrig, M. A.; Kukolich, S . G. Chem. Phys. Lett. 1990, 167,57.
(23)Gough, T.E.;Miller, R. E.;Scoles, G.Appl. Phys. Lett. 1977,30, 338. (24)Miller, R. E.Science 1988,240,447. (25) Lovejoy, C.M.; Schuder. M. D.; Nesbitt, D. J. J. Chem. Phys. 1987, 86,5337.
The Journal of Physical Chemistry, Vol. 96, No. 3, 1992 1089
Two Isomeric Forms of N20-HCN TABLE [I: Summrn of the Rotatioarl Constants for the L h r and Slipped-Parallel lsN,O/HCN Complexes” Linear ISNNO-HCN Isomer ._.
B”
0.036745 (23) YO
B’
0.036995 (23)
3297.8141 (5)
A“
Slipped-Parallel ON15N/HCN Isomer 0.336425 (21) A‘ 0.335 420 (1 1)
E’’ C”
0.0926356 (66) 0.072295 1 (48) YO
B’ C’
0.0926624 (29) 0.0722826 (24)
3309.4577 (5)
“The numbers in parentheses are the errors reported as one standard deviation. The errors in the vibrational origins reflect the uncertainties in the HCN monomer transitions used to establish absolute frequency calibration. All values are reported in cm-I.
was removed from the gas mixture. The two transitions with opposite sign, located at 3298.06049 (50) and 3298.03343 (50) cm-l,H)are the 1-type doublet components of the HCN monomer R(l) transition associated with the 11’0 01’0 hot band and were used to obtain the absolute frequency calibration of the spectrum. The fact that the optothermal signals for the monomer and the complex have opposite signs indicates that the latter dissociates in a time which is short with respect to the flight time of the molecules from the laser excitation point to the bolometer. In fact, careful examination of the individual transitions reveals a 50 (1) MHz Lorentzian component to the line widths, which is in excess of the instrumental broadening. This corresponds to a predissociation lifetime of 3.15 (5) ns, which is consistent with the previously proposed empirical c o r r e l a t i ~ nbetween ~~ the f r e quency shift (-1 3.7 cm-’) and the predissociation lifetime. The molecular constants determined from fitting the above spectrum are summarized in Table I. (Transition frequencies for all of the spectra reported here are available on the microfilm version of this paper.) The fact that the rotational constant increases slightly in going from the ground to the excited vibrational state suggests that the hydrogen bond length decreases slightly upon excitation, which is consistent with the red shift observed for this C-H stretch, due to the associated increase in the intermolecular well depth. What is surprising is that the centrifugal distortion constant increases due to vibrational excitation, which is clearly inconsistent with a stronger hydrogen imilar inconsistencies have been reported for the C02-HF, bond. S SCCFHF, and SCO-HCN complexes,&B which can be explained in terms of the quasi-linear nature of these species. It is interesting to note that k, (0.010 mdyn/A), determined from the centrifugal distortion constant reported in Table I and assuming the pseudodiatomic model for the complex,31is considerably smaller than the intermolecular stretching force constants estimated for many other hydrogen bonded c o m p l e x e ~ . ~This * ~ ~is again consistent with the quasi-linear picture for the N20-HCN complex in which the intermolecular bending potential is very shallow. Although the spectrum reported above clearly indicates that the d a t e d complex is, at least approximately, linear, a single ground-state rotational constant cannot be used to differentiate between the four possible linear structures. Nevertheless, two of these can be eliminated owing to the fact that they would have “free” C-H stretches and therefore would not have the large red shift that is observed in the present spectrum. To differentiate between the remaining two linear structures, the spectrum of the comsponding 15N20/HCNcomplex was recorded. The rotational
-
(26) Baiocchi, F. A.; Dixon, T. A.: Joyner, C. H.; Klemperer, W. J . Chem. Phys. 1981, 74, 6544. (27) Fraser, G . T.; Pine, A. S.;Suenram, R. D.; Dayton, D. C.; Miller, R. E. J . Chem. Phys. 1989,90, 1330. (28) Jaman, A. I.; Legon, A. C. J. Mol. Srrucr. 1987, 158, 205. (29) Dayton, D. C.; Marshall, M. D.; Miller, R. E. J. Chem. Phys. 1991, 95, 785. (30) Choe, J. I.; Tipton, T; Kukolich, S.G. J. Mol. Spectrosc. 1986, 117,
292. (31) Millen. D. J. Cun.J. Chem. 1985, 63, 1477. (32) Legon, A. C.;Millen, D. J. Acc. Chem. Res. 1987, 20, 39.
constants and vibrational band origin obtained by fitting this spectrum are given in Table 11. Centrifugal distortion was not included in this fit since only low-J transitions were measured in an effort to conserve the W N O . As expectad, isotopic substitution of the N 2 0 subunit has little effect on the C-H stretching frequency in the complex. It is now straightforward to make use of the rotational constants for these two isotopomen to determine the distance of the terminal nitrogen in N 2 0 from the center of mass of the complex. This was done using Kraitchman’s e q ~ a t i o n ~for ~ . ’a~linear molecule, with the result being 2.913 A. If the monomer bond lengths are assumed to be valid for the complex, the rotational constant obtained for the normal isotopic species can be used to determine the intermolecular bond lengths assuming either the NNO-HCN or ONN-HCN structures, namely, RGH = 2.415 A and RN-H = 2.329 A. With these values, the distance of the terminal nitrogen atom from the centers of mass can be determined for these two proposed structures, namely, 3.1582 and 0.7605 A, respectively. From this it is clear that the linear complex observed in this study corresponds to the HCN subunit being hydrogen bonded to the oxygen end of the N20. The fact that the nitrogen atom to center of mass distances determined from Kraitchman’s equation and from the rigid linear molecule differ by 0.245 A is probably another indication that this system is not rigid. Slipped-ParallelONN/HCN Isomer. In searching for a second isomer of N20/HCN, we were once again guided by the results reported previously for CO2-HCN,*-l0 which has a stable Tshaped, anti-hydrogen-bondedstructure. The analogous N 2 0 / HCN complex would obviously have a “free” C-H stretch and therefore a small monomer-to-complex frequency shift. Figure 2 shows the spectrum recorded near the origin of the C-H stretching vibration in HCN monomer. The experimental conditions were identical to those used to record the spectrum of the linear 14NNO-HCN complex. In attempting to assign this spectrum,we noted that, for a T-shaped HCN-N20 complex, the C-H stretching vibration would give rise to an A-type band, while careful inspection of this spectrum reveals that it is a B-type band, suggesting that the C-H stretching coordinate lies along the B axis of the complex. Although this clearly rules out the T-shaped structure suggested above, the small monomer-to-complex frequency shift still indicates that the C-H coordinate is not directly involved in hydrogen bond formation. Since the monomer-to-complex frequency shift is small for this vibrational band, it overlaps with the vI band of HCN dimer. To avoid confusion, the dimer transitions have been marked with an asterisk. The transition which appears in the “negative” direction is the P(l) transition of the HCN monomer (3308.5204(5) m-’ (ref 30)), which provided a convenient absolute frequency calibration. An easily distinguishable B-type Q-branch is evident in the expanded central portion of the spectrum shown in Figure 2, as is the beginning of an R-branch progression. The assignment of these transitions to K, = 1 0 is confirmed by the fact that the RPo(l) transition is missing from this subband. An initial estimate for B + C can be made from the spacings between the R-branch transitions, while the spacing between the origins of the K subbands gives an initial estimate of 2A. Another Q branch is found approximately 2A lower in frequency than the Wo(J) subband, which is essentially its mirror image. This Q-branch is located near 3309.2cm-’and is unambiguously assigned to the pQl subband. This procedure for finding subband origins can be continued, with the end result being the assignment of all of the subbands listed in Figure 2. Note that the symmetric top designations have been used for convenience, even though our assignment and fitting will clearly show that this species is actually an asymmetric top. This notation is nevertheless justified since the spectrum is that of a near-prolate symmetric top. Ground state combination differences were calculated from the assigned transitions and fit to a Watson’s A-type Hamiltonian in the F representation. This fit yielded the ground state rotational
-
(33) Kraitchman, J. Am. J . Phys. 1953, 21, 17. (34) Costain, C. C. J . Chem Phys. 1958, 29, 864.
1090 The Journal of Physical Chemistry, Vol. 96, No. 3, 1992
Dayton et al.
Slipped-Parallel ONN‘4/HCN
330 Figure 2. Rovibrational spectrum assigned to the slipped-parallel “N20/HCN isomer. The transitions marked with an asterisk are assigned to the vI band of HCN dimer and the transition appearing in the ‘negative” direction is the HCN monomer P( 1) transition. The insert is an expanded view of the central region of the spectrum. Indicated in this insert are the RQo(J)and RR,,(J) transitions. The absence of the RPo(l)transition and the presence of the RPo(2)transition confirms the assignment of the K. = 1 0 subband. The approximate origins of the remaining subbands in the spectrum are indicated below the baseline.
-
and centrifugal distortion constants summarized in Table I. The large standard deviation associated with D f results from its strong correlation with the A” rotational constant. By fixing the ground-state rotational constants at the values determined from the above fit, we fit the 160 wiped transitions to the excited-state rotational and centrifugal distortion constants and the vibrational band origin. Once again, the large standard deviation obtained for DL is a result of its strong correlation with A’, As noted earlier, the rotational constants reported in Table I were used by Pauley et al.22to aid in their search for the microwave spectrum. The constants obtained from these two studies are in excellent agreement. In trying to establish a structure for this complex, we begin by noting that the inertial defect (A = I, - I, - I,,) is relatively small (1.0418 amu A2), suggesting an essentially planar structure. Taken together with the fact that the spectrum is B-type and the C-H stretch is “free” of the intermolecular bond, it seems clear that the two monomer units must be essentially parallel to one another, with the A axis of the complex being perpendicular to the C-H stretching coordinate. Indeed, if we assume that the A axis passes through the centers of mass of the two monomer units, the A rotational constant of the complex can be estimated from the monomer rotational constants (B(N20) = 0.419011 cm-’ (ref 35) and B(HCN) = 1.478 221 8 cm- (ref 30)) to be 0.3265 cm-*, in reasonable agreement with the experimental value (0.344 247 (27) cm-l). Qualitatively, therefore, we can say that the second isomer of N,O/HCN has a parallel or slightly slipped-parallel geometry. This structure is not too surprising, given that HCN and N 2 0 both have large quadrupole moments. Indeed, the quadrupolequadrupole interactions tend to favor a parallel geometry, as illustrated by the C2H2-C02,36(N20)2,37and (C02)238+39 complexes. (35) Amioy, C.; Guelachvili, G. J . Mol. Specrrosc. 1974, 51, 475. (36) Huang, Z. S.;Miller, R. E. Chem. Phys. 1989, 132, 185. (37) Huang, Z. S.;Miller, R. E. J. Chem. Phys. 1989, 89, 5408.
TABLE UI: Summary of the R,
and 8 , Values Calculated for the SliDped-P.rrllel NtO/HCN’ moment & , A , , e deg av 14N,0/HCN I,, I, 3.2615 78.843 & = 3.2583 (96) I ~ I, , 3.2615 81.348 , e = 79.685 (2.5) I; 3.2519 78.856 ISN2O/HCN I,, I, 3.2662 78.473 & = 3.2629 (99) I,,. I, 3.2662 80.928 ,e. = 79.296 (2.5)
