Hydrogen Bonding with a Hydrogen Bond: the CH4 H2O Dimer and the Pentacoordinate Carbon

Supplementary Information

X-HC hydrogen bonds in n-alkane-HX (X = F, OH) complexes are stronger than C-HX hydrogen bonds R PARAJULI* and E ARUNAN** *Department of Physics, Amrit Campus, Tribhuvan University, Kathmandu, Nepal **Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bengaluru 560012, India

Supplementary Materials: Superscripts 'mono' is for monomer and 'comp' is for complex

Table S1: Coordinate of Propane optimized at B3LYp/6-311++g(d,p)

Nuclear Positions X/Y/Z coordinate (Angstrom)

1C 0.000 1.277 0.812 2H 0.883 1.322 2.831 3H -0.883 1.322 2.831 4C 0.000 0.000 -1.831 5H 0.876 0.000 -3.893 6H -0.876 0.000 --3.893 7H 0.000 2.174 -1.146 8C 0.000 -1.277 0.812 9H -0.883 -1.322 2.831 10H 0.883 -1.322 2.831 11H 0.000 -2.174 -1.146

Table S2: Positions of electrostatic potential (ESP) extrema mapped on 0.001 (a.u.) and value at extremum points of propane Number of Surface minima: 5 Value of # EPS X/Y/Z coordinate (Angstrom)

1 -2.58 -0.011 -2.492 -1.826 2 -2.56 0.012 -1.018 -2.324 3 -1.94 -0.001 0.025 2.680 4 -2.56 0.018 0.969 -2.315 5 -2.58 0.004 2.523 -1.794

Number of Surface maxima:8 Value of # EPS X/Y/Z coordinate (Angstrom) (kcal/mol) 1 6.84 -2.068 -1.272 -1.633 2 6.22 -2.046 -0.004 2.010 3 6.84 -2.068 1.272 -1.633 4 7.14 -0.005 -3.271 1.201 5 7.15 -0.001 3.242 1.246 6 7.15 2.027 -1.276 -1.694 7 6.83 2.060 0.008 1.987 8 6.22 2.026 1.234 -1.694

Table S3 Coordinates of butane optimised at B3LYp/6-311++g(d,p)

Nuclear Positions X/Y/Z coordinate (Angstrom) 1(C ) 1.962 -0.121 -0.064 2(C ) 0.568 0.514 0.272 3(C ) -0.568 -0.514 -0.272 4(C ) -1.962 0.121 0.064 5(H ) 2.110 -0.751 -0.397 6(H ) 2.748 0.639 0.338 7(H ) 2.110 -0.751 -0.397 8(H ) 0.464 1.165 0.617 9(H ) 0.464 1.165 0.617 10(H ) -0.464 -1.165 -0.617 11(H ) -0.464 -1.165 -0.617 12(H ) -2.110 0.751 0.397 13(H ) -2.748 -0.639 -0.338 14(H ) -2.110 0.751 0.3972

Table S4: Positions of electrostatic potential (ESP) extrema mapped on 0.001 (a.u.) and value at extremum points Number of Surface minima: 8 Value of EPS in # X/Y/Z coordinate (Angstrom) Surface Maxima 1 -2.61 -3.397 1.491 -0.012 2 -2.61 -1.911 2.195 0.014 3 1.84 -0.068 0.054 2.001 4 -2.58 -0.090 2.503 -0.035 5 1.83 0.169 0.020 -2.004 6 -2.58 0.1811 -2.466 -0.007 7 -2.61 1.909 -2.194 -0.001 8 -2.60 3.352 -1.550 -0.012 Number of Surface maxima: 10 Value of # EPS X/Y/Z coordinate (Angstrom) (kcal/mol) 1 7.09 -3.658 -1.682 -0.010 2 6.81 -2.238 1.483 2.057 3 6.81 -2.106 1.491 -2.061 4 6.10 -0.323 -1.889 -2.069 5 6.08 -0.349 -1.810 2.117 6 6.10 0.276 1.888 -2.064 7 6.10 0.285 1.869 2.076 8 6.80 2.181 -1.551 2.017 9 6.82 2.159 -1.486 -2.063 10 7.10 3.666 1.675 0.013

Table S5: Coordinates of pentane optimised at B3LYp/6-311++g(d,p)

Nuclear Positions X/Y/Z coordinate(Angstrom)

1C 1.284 -0.523 0.000 2C 0 0.314 0.000 3C -1.284 -0.523 0.000 4C 2.560 0.324 0.000 5C -2.560 0.324 0.000 6H 1.284 -1.183 -0.877 7H 1.284 -1.183 0.876 8H 0.000 0.975 -0.877 9H -0.000 0.975 0.877 10H -1.284 -1.183 0.876 11H -1.284 -1.183 -0.876 12H 3.455 -0.302 0.000 13H 2.605 0.970 -0.883 14H 2.605 0.970 0.883 15H -2.605 0.970 -0.883 16H -2.605 0.970 0.883 17H -3.456 --0.302 0.000

Table S6: Positions of electrostatic potential (ESP) extrema mapped on 0.001 (a.u.) and value at extremum points of pentane Number of Surface minima: 8 # Value of X/Y/Z coordinate (Angstrom) EPS in Surface Maxima

1 -2.69 -3.779 1.886 -0.009 2 -2.75 -2.210 2.371 -0.022 3 -2.57 -0.981 -2.597 0.002 4 1.78 -0.711 -0.087 2.002 5 1.79 -0.605 -0.107 -2.003 6 -3.05 -0.063 2.420 -0.005 7 1.79 0.717 -0.107 -2.003 8 1.78 0.744 -0.088 2.002 9 -2.57 1.000 -2.600 -0.0006 10 -2.75 2.139 2.353 -0.0254 11 -2.70 3.639 2.014 -0.008 Number of Surface maxima: 10 Value of # EPS X/Y/Z coordinate (Angstrom) (kcal/mol) 1 7.04 -4.548 -1.152 0.002 2 6.74 -2.605 1.746 -2.036 3 6.75 -2.494 1.735 2.039 4 6.08 -1.293 -1.958 2.044 5 6.09 -1.237 -1.906 -2.077 6 6.02 -0.053 1.643 2.114 7 6.01 0.063 1.614 -2.129 8 6.08 1.219 -1.958 2.043 9 6.09 1.276 -1.906 -2.077 10 6.74 2.555 1.746 -2.035 11 6.75 2.563 1.726 2.049 12 7.04 4.553 -1.145 -0.002 TABLE S7: Optimized H-C bond distances, FHC bond angles, shift in F-H stretching frequency with respect to monomer frequency () in cm-1, change in F-H distance a n d C – H d i s t a n c e * ( r) in Å and interaction energy (E) in kJ/mol for F-H •••alkane complexes (alkane  1n-propane, 2n-butane, 3n-pentane).

M05-2X/6-311++G**

RH-C FHC r H-F E 0.0032 -75 -7.9 1a 2.26141 178.0 0.0020* 0.0038 1b 2.36637 179.3 -88 -7.1 0.0036* 0.0037 a 2 2.40899 171.739 -82 -9.4 0.0032* 0.0039 2b 2.38929 179.591 -90 -9.6 0.0035* 0.0033 3a# 2.25998 178.836 -70 -7.6 0.0022* 0.0040 -91 3b 2.40446 172.991 -9.6 0.0034* 0.0044 3c 2.35978 179.377 -99 -9.3 0.0036* # Not fully optimized

TABLE S8: Optimized H-A bond distances, DHA bond angles, shift in D-H stretching frequency with respect to monomer frequency (Δν) in cm−1, change in O-H distance and C-H distance * (Δr) in A and interaction energy (ΔE) in kJ/mol for H-O-H...alkane complexs (alkane  1propane 2butane, 3pentane). Superscripts with # are alkane ...OH interactions. D is donor atom and A is acceptor atom.

M05-2X/6-311++G**

RH-A DHA r  E a 1 0.0006 16 -4.1 2.63291 145.031 0.0012* 1b$ Geometry distorted during optimization 2a 0.0008 2.55341 163.300 10 -4.5 0.0012* b 2 0.0012 -6.7 2.65552 179.6 12 0.0017* 3c 0.0012 2.65105 175.236 10 -6.9 0.0016* 1b# 2.61963 147.3 -0.0011 7 -4.4 2b# 2.65665 127.241 -0.0018 1 -5.3 3b# 2.61837 143.320 -0.0020 4 -5.3 $ Not fully optimised at MP2 level of theory

O b O b TABLE S9: Penetration parameters rA(rA - rA ), rH(rH - rH ) of F-H •••Alkane

1 2 3 O complexes in Å (Alkane  n-propane, n-butane, n-pentane). rA (non-bonding radius

b O of acceptor atom) rA (bonding radius of acceptor) rH (non bonding radius of Hydrogen

b atom) rH (bonding radius of Hydrogen atom)

B3LYP/6-311++G** MP2/6-311++G** O b O b O b O b rA rA rA rH rH rH rA rA rA rH rH rH 1a 2.218 1.609 0.609 1.132 0.821 0.311 2.222 1.671 0.550 1.122 0.849 0.273 1b 2.095 1.613 0.482 1.132 0.809 0.323 2.095 1.644 0.451 1.122 0.824 0.298 2a 2.192 1.622 0.570 1.132 0.820 0.312 2.138 1.680 0.458 1.122 0.870 0.252 2b 2.092 1.621 0.471 1.132 0.812 0.320 2.092 1.658 0.434 1.122 0.830 0.292 3a* 2.213 1.598 0.615 1.132 0.820 0.312 2.221 1.643 0.578 1.122 0.842 0.279 3b 2.097 1.620 0.477 1.132 0.812 0.320 2.104 1.680 0.425 1.122 0.852 0.270 3c 2.108 1.632 0.476 1.132 0.817 0.315 2.115 1.652 0.463 1.122 0.821 0.301 * Not fully optimized in MP2 level of theory

Table S10: Change in atomic volumes (V) of the “H” of F-H •••Alkane Complexes B3LYP/6-311++G** MP2/6-311++G** Comp mono Comp mono VH VH V VH VH V 1a 14.42025 16.43981 -2.01957 14.26714 15.75788 -1.49075 1b 14.14589 16.43981 -2.29392 13.43665 15.75788 -2.32124 2a 14.52102 16.43981 -1.91879 14.90412 15.75788 -0.85376 2b 14.38731 16.43981 -2.0525 13.85163 15.75788 -1.90625 3a* 14.46382 16.43981 -1.97599 14.29418 15.75788 -1.46371 3b 14.31575 16.43981 -2.12406 14.07087 15.75788 -1.68701 3c 14.60081 16.43981 -1.83901 13.81003 15.75788 -1.94786 * Not fully optimized in MP2 level of theory

Table S11: Change in atomic populations (N) of the “H” of F-H •••Alkane complexes

B3LYP/6-311++G** MP2/6-311++G** Comp mono Comp mono NH NH N NH NH N 1a 0.307789 0.293055 0.014734 0.295376 0.281364 0.014012 1b 0.309726 0.293055 0.016671 0.287982 0.281364 0.006618 2a 0.308748 0.293055 0.015693 0.304756 0.281364 0.023392 2b 0.310325 0.293055 0.01727 0.298298 0.281364 0.016934 3a* 0.308394 0.293055 0.015339 0.309697 0.281364 0.028333 3b 0.309237 0.293055 0.016182 0.309536 0.281364 0.028172 3c 0.310888 0.293055 0.017834 0.303838 0.281364 0.022474 * Not fully optimised in MP2 level of theory

Table S12: Change in atomic energies of the “H” of F-H •••Alkane complexes.

B3LYP/6-311++G** MP2/6-311++G** Comp mono Comp mono EH EH E EH EH E 1a -0.30482 -0.30522 -0.0004 -0.29556 -0.2964 -0.00085 1b -0.30592 -0.30522 0.000698 -0.28929 -0.2964 -0.00711 2a -0.30487 -0.30522 -0.00035 -0.30408 -0.2964 0.007676 2b -0.30552 -0.30522 0.0003 -0.29758 -0.2964 0.001174 3a* -0.30517 -0.30522 -4.5E-05 -0.31258 -0.2964 0.016176 3b -0.30476 -0.30522 -0.00046 -0.31199 -0.2964 0.01559 3c -0.30571 -0.30522 0.000487 -0.30533 -0.2964 0.008922 * Not fully optimised in MP2 level of theory

Table S13. Change in atomic first moments of the “H” of F-H •••Alkane complexes.

B3LYP/6-311++G** MP2/6-311++G** Comp mono Comp mono MH MH M MH MH M 1a 0.123573 0.128771 -0.0052 0.120266 0.126785 -0.00652 1b 0.12356 0.128771 -0.00521 0.118258 0.126785 -0.00853 2a 0.124086 0.128771 -0.00468 0.125119 0.126785 -0.00167 2b 0.124122 0.128771 -0.00465 0.119378 0.126785 -0.00741 3a* 0.123621 0.128771 -0.00515 0.116967 0.126785 -0.00982 3b 0.123992 0.128771 -0.00478 0.117641 0.126785 -0.00914 3c 0.12436 0.128771 -0.00441 0.11733 0.126785 -0.00946 * Not fully optimised in MP2 level of theory Figure S1: Optimized Structure of WaterAlkane Complex at B3LYP/6-311++g** level.