1A08!"#$%&'()*#+1,-./01 2-./3245678129:;<22=>>?12@ABC1!"#$%&'()*+,-./01-23456789:;&'<=>?@ABCD+EFG<(3HI;pH+JKLMA>NOPFQR2+STLCO32–3HCO3–QU0VWR2->?XW
YZ+[\]^_<C`R3]+Zabc0d-efg\0hijk>lm;no+pq&'+
rQ8QR23s+[\g\<+tuvwxjk2->&'<y=>?
z+{|;9:}0y77~3uX<$%&'v

jkWzQ(;7W?

<(3NH4HCO3+&0{2CW&'+<m/z = 62 +v jk2
13$%&'+y+<=|QAk2->[1]?<(3Q%K$ 7<¡W¢0£¤¥;¦+§¨©ª«¬­L®­j¯WC`°+±¤&²<3®­³0(tuR;7W´µ¥vC>zQv¶·jk213zkv$%&'+y+<=|QAk2->[2,3]?R7R;vuX<3¶70¸iRWQ-|¹º(;»3s+no(~72-;
7W?
¼½<3ab initio ¾¿0{>ÀÁ(3Q%K$ 7+$%&'+C`ÂÃ(´<=>v3
ÄÅÆÇ<=kB&+ÈÉw(ÊË0Ì»3z+&'vÍÎ0tuÏ>zQLÐR2->?R
7R&'vtuR2->ÆÑÒ<(3&'v$%&'+&+ÓÔQR2Õ¡3ÈÉwvH
Ö0×»;>QØ jk2->[4]?
ÙÚÛÜ(cis-cis H2CO3Qcis-trans H2CO3LÝhÞßàLá-2âãÖäåæG0ç
iR3FTMW&²è<sk+éÚêëìLRW?zk(<+$%&'+íî+¸i<=>?XWzk+&'+9 ïðDy R3cis-cis H2CO3Qcis-trans H2CO3+r0noLñÎRW[5]?
!ab initio¾¿òóô#$%&'0õÏ>ab initio¾¿(ö÷¹ºjk2->v3ÛÜ({øa+§-¾¿ùCCSD(T)/cc-pVQZúLûW?s+üV(3íý¹ºjk2->üVQþ»¼ÿR
2->[6]?$%&'0(1 +(A)0ÐRW{|03! "#+no$}DvtuÏ>?íÍÎno

(cis-cisD<=3cis-transD(íÍÎno{y 1.74 kcal/mol%&§-¨©ª«L'8?

(+(B)03_)H–O–C=O+JK0{>$}K+*+,-.¥LÐRW?cis-cisD7cis-transD/+$}K+01+§j( 10.5 kcal/mol<=3cis-transDyÍÎ0tuÏ>QAk>?
cis-trans H2CO3vCS203R4_5+a6b67½08¡;79':«;L'8ùµa = 1.0 D, µb= 2.9 Dú+0<R23cis-cis H2CO3(C2v203R<=6<=>b6½>+?0@j

1AB8+$}D+no(A)Qs+$}K+*+,-¨©ª«(B)

CA$%&'+Q%K$¨©ª«

D/+&+;79':«;L'8ùµb = 0.2 Dú?XWcis-cis H2CO3Qcis-cis D2CO3(8+EF; GXW(9 GLpR2->+<orthoQparaÆÇ0&7k3skHkGIJ¾9Kv$;>?
C 0$%&'+&LM+¨©ª« LÐRW?íÍÎno+cis-cisD(NO0ÍÎ;$}D<=>cis-transD/+$}K+P3Q%K$ 0&Ï>v3s+&+01v§-zQ7yÄÅÆÇ+$%&'vÍÎ<=>zQvØQjk>?
$%&'(3RS< T %0UVRW%K$ LFD++WWFXYLZR2&'
L[\2]W[^_L3ÝhÞßà5<hÞR88`a ! a<bgG0ciÏ>zQ0{23âãÖäåæG0C`RW?éÚê( FTMW &²èLá-2 RW?
XW3 defgL,h>QU0i3L¶ÎÏ>WY03jklQ+9Um&²nLá-W?
XW+o~09LFXY0Wk2á->zQ<39

ïðD+y

Ï>zQv<¡W?
!üVòp#óô+üV3cis-cis H2CO30

r0noQab initio noa<ÃÏ>b-typeëì q 5Q3s+9 ïð^ (.

Dcis-cis D2CO3+ r 5+Úêëìv jkcis-cis H2CO3r0 structure

ab initio br(C=O) (Å)
r(C–O) (Å)! (O=C–O) (º)
r(O–H/D) (Å)! (C–O–H/D) (º)

1.20243(28)1.33951(14)125.6941(95)0.968 c / 0.963 d
105.7 d

1.203
1.336
125.7
0.963
105.7

Ïv2+&'+z}{|( 0.1 uÅ2MaQ@

cis-trans H2CO3

r0 structure

ab initio bj-}+~Q;3zk+&'v4_&'r(C=O) (Å)
r(C–Ocis) (Å)
r(C–Otrans) (Å)! (O=C–Ocis) (º)! (O=C–Otrans) (º)
r(Ocis–H/D) (Å)
r(Otrans–H/D) (Å)! (C–Ocis–H/D) (º)! (C–Otrans–H/D) (º)

1.18788(94)1.3447(13)1.3568(17)126.78(15)122.94(12)0.968 c / 0.963 d
0.968 c / 0.963 d
106.1 d108.6 d

1.194
1.354
1.336
125.2
124.3
0.963
0.963
106.1
108.6

W?XWcis-trans H2CO3 0õR2(3a-typeëìQb-typeëì+s½Ltu^¾ CT 5+ëìv jk3XWs+9 ïðD ! "Ïv2+ëìL Ï>zQv<¡W?
jkWëì(Ïv2Watson+A-reducedwjxR<yR3&'Î÷LñÎRW?

<=>zQv¶·jkW?XW3 RWÚêÎ÷73zk+&'+r0noLñÎRW?s+3¼+no+Î÷(ab initio¾¿~3XW(s+}~0ÎRW?ñÎj
kWcis-cisDQcis-transD+noÝ;«L^ ( 0XQYW?
z+ÀÁ<ÄÅÆÇ+8+$%&'$}D3cis-cis H2CO3Qcis-trans H2CO3vÆÇ<ÍÎ0tuR2->zQy¶·R3s+noLñÎRW?j0ÙP3Þl0{>[\g\<+¸ivwxjk>?

a  5(í@y+b CCSD(T)/cc-pVQZ <+¾¿
c ab initio ~{y 0.005 Å Ì-~0Îd ab initio ~0Î!#[1] J. K. Terlouw, C. B. Lebrilla, H. Schwarz, Angew. Chem. Int. Ed. Engl. 26, 354 (1987).
[2] M. H. Moore, R. K. Khanna, Spectrochimica Acta Part A 47, 255 (1991).
[3] W. Hage, K. R. Liedl, A. Hallbrucker, E. Mayer, Science 279, 1332 (1998).
[4] T. Loerting et al., Angew. Chem. Int. Ed. 39, 891 (2000).
[5] T. Mori, K. Suma, Y. Sumiyoshi, Y. Endo, J. Chem. Phys. 130, 204308 (2009).
[6] P. P. Kumar, A. G. Kalinichev, R. J. Kirkpatrick, J. Chem. Phys. 126, 204315 (2007).