Jan Lundell Department of Chemistry, University of Jyväskylä The Hydrogen Bond Jan Lundell Department of Chemistry, University of Jyväskylä

The Hydrogen Bond

The Hydrogen Bond Adenine Thymine Cytosine Guanine Peter Agre (Nobel Prize, 2003): The purest form of hydrogen bond there is…

The Hydrogen Bond ”The hydrogen nucleus held by two octets constitutes a weak bond” W.M.Latimer and W.H.Rodebush, JACS 42, 1920, 1419 ”Under certain conditions an atom of hydrogen is attracted by rather strong forces to two atoms instead of only one, so that it may be considered to be acting as a bond between them. This is called a hydrogen bond.” L. Pauling, Nature of Chemical Bond, 1939

The Hydrogen Bond HCOOH in the gas phase – IR ( from webbook.nist.gov ) Absorbance Wavenumber

The Hydrogen Bond ”A hydrogen bond exists between the functional group, A-H, and an atom or a group of atoms, B, in the same or different molecules when (a) there is evidence of bond formation (association or chelation) (b) there is evidence that this new bond linking A-H and B specifically involves a hydrogen atom already bonded to A” G.C.Pimentel, A.L.McClellan, The Hydrogen Bond, 1960

The Hydrogen Bond bond distance A-H  H...B A-H < H...B Strong Medium Weak bond distance A-H  H...B A-H < H...B A-H << H...B H...B (Å) 1.2 - 1.5 1.5 - 2.2 2.2 - 3.2 A...B (Å) 2.2 - 2.5 2.5 - 3.2 3.2 - 4.0 bond angle (º) 175 - 180 130 - 180 90 - 150 binding energy (kJ/mol) 60 - 170 15 - 60 < 15

The Hydrogen Bond dimers of strong acids and bases in the gas phase Medium Weak dimers of strong acids and bases in the gas phase acids dimers of weak acids and bases in the gas phase Acid salts alcohols, phenols C-H...O/N Proton sponges hydrates O/N-H... HF complexes all biological molecules dihydrogen bonds

The Hydrogen Bond ”A hydrogen atom with only one stable orbital cannot form more than one pure covalent bond and the attraction of the two atoms observed in hydrogen bond formation must be due largely to ionic forces”” L.Pauling, The Nature of Chemical Bond, 1939 d+ d-

The Hydrogen Bond YHB = aYa + bYb + cYc + dYd + eYe Ya A-H…B covalent A-H bond Yb A- -H+ …B ionic A-H bond Yc A- -H…B+ charge transfer , A…B bond Yd A+ -H- …B ionic A-H bond Ya A-H- …B+ charge transfer, H…B bond C.A.Coulson, In Hydrogen Bonding, D.Hadzi (Ed.) 1959, pp. 339-360. O-H … O with O … O = 2.8 Å Yb + Yd contribute 65 % of the hydrogen bond energy

Interaction energy of a H-bond Supermolecular approach Eint = EAB – (EA + EB)

Interaction energy decomposition scheme

HCN…HCN ( MP2 ) A.Heikkilä, J.Lundell, J.Phys.Chem. A 104, 2000, 6637-6643

Symmetry-Adapted Perturbation Theory (SAPT) K.Szalewicz, K.Patkowski, B.Jeziorski ,Struct.Chem. 116, 2005, 43-117

R.A.Christie, K.D.Jordan, Struct.Chem. 116, 2005, 27-41

Having more than two molecules? S.S.Xantheas Struct.Chem. 116, 2005, 119-148

S.S.Xantheas Struct.Chem. 116, 2005, 119-148

Non-additive (cooperative) effects

S.S.Xantheas Struct.Chem. 116, 2005, 119-148

Basis set superposition error (BSSE) Not perfect basis sets, so needs to borrow from the neighbour… HNC…HCN The ”cure”: Counterpoise correction (Boys-Bernardi )

S.S.Xantheas Struct.Chem. 116, 2005, 119-148

J.R.Lane, H.G.Kjaergaard, J.Phys.Chem. 131, 2009, 034307

Changes upon hydrogen bonding… G.A.Jeffrey, An Introduction to Hydrogen Bonding, 1997

HCOOH photochemistry in matrices H2O + CO vs CO2 + H2 t-HCOOH hn J.Lundell, M.Räsänen, J.Phys.Chem. 99, 1995, 14301.

H2O...CO : Two stable complex structures 2.323 2.365 CCSD(T)/6-311++G(2d,2p) Eint,cp = -5.29 kJ mol-1 Eint,cp = -3.17 kJ mol-1 J.Lundell, J.Phys.Chem. 99, 1995,14290 J.Lundell, Z.Latajka, J.Phys.Chem. A 101, 1997, 5004

H2O...CO : Experiments In situ photolysis of formic acid in a solid argon matrix +13 2130 +10 2148 1656 +2 1596 -22 3826 -9 3628 -17 3864 3724 Dw calc. Dn exp. JPC 99, 1995, 14290: MP2/6-311++G(2d,2p) JPC 99, 1995, 14301: Ng-matrices HOH...CO

H2O...CO : Experiments Annealing the matrix after photolysis argon krypton xenon

H2O...CO : Experiments Both HOH...CO and HOH...OC can be made -2 2118 +10 2130 calc. -5 2128 +8 2142 Xe -6 +9 2145 Kr +11 2149 Ar 2154 Gas phase HOH...CO HOH...OC MP2/6-311++G(2d,2p) CO stretch

Can we do more?

Anharmonic calculations: cc-VSCF Vibrational Schrödinger equation in mass-weighted normal mode coordinates single-mode wavefunctions, energies and effective potentials 2nd order perturbation theory for correlation effects between different vibrational modes pairwise interactions between normal modes

Anharmonic calculations: cc-VSCF Grid-approach of PES: - 8  8 or 16  16 grids - points chosen equidistantly over an interval defined by the harmonic frequency of a vibrational mode: Qmax ~ inverse square root of the frequency G.M.Chaban, J.O.Jung, R.B.Gerber, J.Phys.Chem. A 104, 2000, 2772 Implemented in GAMESS-US

MP2/aug-cc-pVTZ + cc-VSCF * CO2...H2

MP2/aug-cc-pVTZ + cc-VSCF

The formic acid monomer: Two conformers MP2/6-311++G(2d,2p) 4544 cm-1 1488 cm-1 trans cis Exp: 4842 cm-1 Exp: 1362 cm-1

IR-pumping at 6934 cm-1 (2 nOH) cis IR trans M.Pettersson, J.Lundell, L.Khriachtchev, M.Räsänen, JACS 119, 1997, 11715

HCOOH anharmonic calculations trans-HCOOH anharmonic harmonic cis-HCOOH E.M.S.Macoas, J.Lundell, M. Pettersson, L.Khriachtchev, R.Fausto, M.Räsänen, J.Mol.Spectrosc. 219, 2003, 70.

Isomerisation of formic acid: The monomer vibr exc tunneling trans cis K. Marushkevich, L.Khriachtchev, M.Räsänen, J.Phys.Chem. A 111, 2007, 2040 Tunneling can be stopped by complexation X

The trans-trans formic acid dimers FAD-tt3 2.408 2.509 Ecp,int (MP2)= -11.81 FAD-tt5 1.896 2.406 Ecp,int (MP2)= -23.36 FAD-tt1 1.684 Ecp,int (MP2)= -66.71 kJ mol-1 FAD-tt4 1.927 1.968 Ecp,int (MP2)= -28.68 FAD-tt2 1.774 2.337 Ecp,int (MP2)= -37.21 FAD-tt6 2.417 Ecp,int (MP2)= -15.39 MP2/6-311++G(2d,2p)

The trans-trans –dimer (FAD-tt1) MP2/6-311++G(2d,2p) cc-VSCF without mode coupling FAD-tt1 in solid argon From M.Gantenberg, M.Halupka, W.Sander, Chem.Eur.J. 6, 2000, 1865

Solid argon FAD-tt1 FAD-tt2 A.Olbert-Majkut, J.Ahokas, J.Lundell, M.Pettersson, Chem.Phys.Lett. 468, 2009, 176.

The trans-trans formic acid dimers Computed relative energies FAD-tt2 FAD-tt3 FAD-tt4 FAD-tt5 FAD-tc2 FAD-tt6 FAD-cc3 FAD-tt1 FAD-tc3 FAD-tc4 FAD-tc5 FAD-tc1 FAD-cc4 FAD-cc2 FAD-cc1 FAD-cc5 cis-FA trans-FA Experimentally observed excitation at 3168 cm-1 (C-H str) FAD-tt3 FAD-tt6

Pumping O-H str in trans-trans dimer ? FAD-tt1 (CD) * * FAD-tt2 ( * ) Excitation at 3540 cm-1 * * * K.Marushkevich, L.Khriachtchev, J.Lundell, M.Räsänen, JACS 128, 2006, 12060

The cis-trans formic acid dimers FAD-tc3 1.814 Ecp,int (MP2)= -29.79 FAD-tc1 1.761 2.287 Ecp,int (MP2)= -41.31 kJ mol-1 FAD-tc5 1.857 Ecp,int (MP2)= -23.20 FAD-tc4 2.502 2.387 Ecp,int (MP2)= -12.74 FAD-tc2 1.950 1.852 Ecp,int (MP2)= -38.02 MP2/6-311++G(2d,2p)

The cis-trans formic acid dimers FAD-tc1 FAD-tt2 1.774 2.337 1.761 2.287 hn (IR) cc-VSCF//MP2 computed wavenumbers [cm-1] x 5 FAD-tc1 FAD-tt2 trans-FA x 1

The cis-trans formic acid dimers 1488.0 cm-1 4543.7 cm-1 4771.5 cm-1 1180.3 cm-1 MP2/6-311++G(2d,2p)

Photoisomerisation of formic acid dimers: Computed relative energies FAD-cc4 FAD-cc2 FAD-tc4 FAD-cc1 FAD-cc5 FAD-tc5 FAD-tt3 FAD-tc3 FAD-tt6 FAD-tc2 FAD-tt5 FAD-tc1 FAD-tt4 FAD-tt2 cis-FA Experimentally observed trans-FA FAD-tt1

The cis-cis formic acid dimers FAD-cc1 Ecp,int (MP2)= -31.82 kJ mol-1 1.878 2.765 FAD-cc2 1.853 Ecp,int (MP2)= -32.10 FAD-cc3 2.370 Ecp,int (MP2)= -20.95 FAD-cc4 2.006 Ecp,int (MP2)= -24.47 2.684 FAD-cc5 1.816 Ecp,int (MP2)= -31.99 MP2/6-311++G(2d,2p)

The cis-cis formic acid dimers Computed relative energies FAD-tt2 FAD-tt3 FAD-tt4 FAD-tt5 FAD-tc2 FAD-tt6 FAD-cc3 FAD-tt1 FAD-tc3 FAD-tc4 FAD-tc5 FAD-tc1 FAD-cc4 FAD-cc2 FAD-cc1 FAD-cc5 cis-FA trans-FA Experimentally observed ? ?

Current topics (Horizons in Hydrogen Bond Research, Paris, Sept 2009) Blue-shifting hydrogen bonds vs red-shifting hydrogen bonds Dihydrogen bonds (for example, H-O-H…HXeH ) Biomolecular systems - Water as biolubricant “Fast spectroscopy” (also dynamic simulations )