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Intermolecular Dihydrogen Bonding in VI, VII, and VIII Group Octahedral Metal Hydride Complexes with Water

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Intermolecular Dihydrogen Bonding in VI, VII, and VIII Group Octahedral Metal Hydride Complexes with Water J. Chem. Sci. (2018) 130:98 © Indian Academy of Sciences https://doi.org/10.1007/s12039-018-1498-0 REGULAR ARTICLE Special Issue on Modern Trends in Inorganic Chemistry Intermolecular dihydrogen bonding in VI, VII, and VIII group octahedral metal hydride complexes with water KARAKKADPARAMBIL S SANDHYAb, GEETHA S REMYAa and CHERUMUTTATHU H SURESHa,∗ aChemical Sciences and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Trivandrum, Kerala 695 019, India bGovernment College Kariavattom, Trivandrum, Kerala, India E-mail: [email protected], [email protected] MS received 19 March 2018; revised 23 May 2018; accepted 24 May 2018; published online 12 July 2018 Abstract. The nature of dihydrogen bonding (DHB) in VI, VII, and VIII group octahedral metal hydride complexes with H2O has been studied systematically using quantum theory of atoms-in-molecule (QTAIM) analysis. A dihydrogen bond (H···H) between hydride ligand and hydrogen of H2O is revealed in QTAIM analysis with the identification of a bond critical point (bcp). The DHB is due to the donation of electron density from the hydride ligand to the hydrogen of H2O. A strong linear correlation is observed between intermolecular ρ H···H distance (dHH) and electron density ( ) at the bcp. Structural parameters suggested the highly directional nature of DHB. Weak secondary interactions between oxygen of water and other ligands contribute significantly to the binding energy (Eint) of DHB complex (2.5 to 13.2 kcal/mol). Analysis of QTAIM parameters such as kinetic- (Gc), potential- (Vc) and total electron energy density (Hc) revealed the partially covalent character of DHB in majority of the complexes while a few of them showed closed shell character typical of purely non-covalent interactions. Keywords. Dihydrogen bond; QTAIM; metal hydrides; non-covalent interaction. 1. Introduction unfolded in many emerging areas such as hydrogen storage, water-splitting reactions, crystal engineering, The term “dihydrogen bond” (DHB) was first proposed catalyst tailoring and catalysis. 15–17 The D–Hδ +···δ +H– by Crabtree et al., in 1996 when they investigated certain A interaction, (where D and A are proton donors and N–H···H–B intermolecular interactions. 1 They also acceptors, respectively) plays a crucial role in proton explored the existence of similar M–H···H–C (M, tran- transfer processes and σ bond metathesis reactions. 18,19 sition metals) type of unconventional hydrogen bonding Szymczak et al., reported in detail the complexation ··· η2 + − and reported the internuclear H H distance, dHH in patterns of ( −H2)/D ···(H2) ···A ion pairs and the range 1.6–2.1 Å. 2 The experimental studies dis- the related dihydrogen elimination reactions. 20 Belkova closed that the stabilizing energy of DHB is within et al., explored the equilibrium between dihydrogen 3–7 kcal/mol 3,4 while considerable number of experi- bond intermediate and associated ion paired dihydro- mental and theoretical studies report on the characteriza- gen complex formation in a system CpRu(dppe)H 5–9 10 tion of DHB systems. Various groups have studied the (dppe = Ph2PCH2CH2PPh2) with HA. Later stud- distinctive features of DHB systems using spectroscopy, ies in this area showed the DHB formation between proton affinity measurements, and analysis of thermo- two metal hydrides, as for example, [OsH2(PMePh2)4]/ dynamic data. 10–14 Today, DHB has been enrolled as [ tBu CpM(H)(CO)3]and[( PCP)Ni(H)]/[CpW(H)(CO)3] tBu tBu 21 a pretty well-understood concept in chemical bonding ( PCP = 2,6-C6H3(CH2P 2)2). Formation of whereas potential new applications of DHB is getting intramolecular DHB has been well established in vari- ous othercomplexsystems,suchas,[IrH2(PMe3)(2-NH2 )( ) ]0/+1 [ ( ) ( ) ( *For correspondence C6H4 PPh3 2 , Ir PEt2Ph 2H2 PPh3 2 2-NH2C5H4 Electronic supplementary material: The online version of this article (https:// doi.org/ 10.1007/ s12039-018-1498-0) contains supplementary material, which is available to authorized users. 1 98 Page 2of8 Page Table 1. Structural parameters, QTAIM parameters and binding energy (Eint) for dihydrogen complex. dpp = 1,2-diphosphine-propane, pae = 2-phospino-1-amine ethane, dpe = 1,2-diphosphine-ethane, dpcp = 1,2-diphosphine-cyclopentane, en = ethylene diamine, imd = imidazole, dpm = 1,2-diphosphine methane, dpe = 1,2 diphosphine ethane, py = 1-pyrrole. 2 Sl. No. Complex interacting with H2OdHH Å ρ au ∇ ρ au Vc au Gc au −Gc/Vc au Eint kcal/mol Eint(sol) kcal/mol ( ) . − . 1. Mn(CO)4 PH3 H2048 0.011 0.035 0 006 0 007 1 218 5 72.8 ( ) . − . 2. Mn(CO)3 PH3 2H1669 0.024 0.046 0 015 0 013 0 886 6 43.1 ( ) . − . 3. Mn(CO)2 PH3 3H1648 0.026 0.046 0 016 0 014 0 869 6 63.6 4. Mn(CO)(PH3)4H1.642 0.027 0.046 −0.016 0.014 0.86 6.73.9 5. Mn(PH3)5H1.641 0.026 0.045 −0.016 0.014 0.864 6.94.0 . − . 6. Mn(CO)3(dpp)H 1 669 0.024 0.044 0 014 0 013 0 889 8 03.1 . − . 7. Mn(dpe)2N2H1624 0.026 0.044 0 015 0 013 0 857 7 14.1 . − . 8. Mn(CO)(dpe)2H1630 0.026 0.044 0 015 0 013 0 861 7 44.2 9. Mn(PH3)4N2H1.634 0.027 0.046 −0.016 0.014 0.859 6.63.6 . − . 10. Fe(dpe)2(CN)H 1 636 0.027 0.046 0 016 0 014 0 867 9 04.4 ( ) . − . 11. Fe(CO)2 PH3 2ClH 1 971 0.014 0.038 0 008 0 009 1 112 5 73.2 ( ) . − . 12. Fe(CO)2 PH3 2FH 2 056 0.012 0.034 0 007 0 008 1 156 5 63.3 . − . 13. Fe(dpe)2(Py)H 1 626 0.027 0.046 0 016 0 014 0 863 6 94.3 . − . 14. Fe(dpe)2(Cl)H 1 643 0.026 0.046 0 015 0 014 0 873 9 04.4 ( ) . − . 15. Re(CO)3 PH3 2H1701 0.024 0.045 0 014 0 013 0 898 7 63.2 ( ) . − . 16. Re(CO)2 PH3 3H1689 0.024 0.044 0 014 0 013 0 887 7 33.3 17. Re(N2)(PH3)4H1.685 0.024 0.045 −0.014 0.013 0.892 6.83.2 18. Re(CO)(PH3)4H1.685 0.025 0.044 −0.014 0.013 0.884 7.03.4 19. Ru(PH3)4(SiH3)H1.727 0.022 0.043 −0.013 0.012 0.912 6.53.3 20. Ru(PH3)3Cl(CO)H 2.006 0.013 0.035 −0.007 0.008 1.125 5.52.8 ( ) . − . 21. Ru PH3 2(CO)2(NCO)H 2 062 0.011 0.033 0 006 0 007 1 177 5 62.8 22. Ru(PH3)3F(CO)H 1.811 0.018 0.042 −0.011 0.011 0.985 5.32.9 . − . 23. Ru(dpe)2ClH 1 718 0.022 0.043 0 013 0 012 0 912 8 53.9 ( )( ) . − . 24. Ru PH3 SiH3 (CO)3H2052 0.011 0.033 0 006 0 007 1 17 5 32.4 25. Ru(PH3)2COCl(imd)H 1.987 0.014 0.035 −0.007 0.008 1.09 6.33.2 . − . 26. Ru(dpm)2ClH 1 72 0.022 0.042 0 013 0 012 0 911 7 73.4 . − . 27. Ru(pae)2ClH 1 645 0.028 0.046 0 016 0 014 0 852 13 26.1 ) . − . 28. Ru(en)(PH3 2ClH 1 72 0.023 0.043 0 013 0 012 0 905 10 65.1J. Chem. Sci. ( ) . − . 29. Mo(CO)3 PH3 (NO)H 1 793 0.02 0.041 0 011 0 011 0 962 6 63.4 30. Mo(PH3)3(CO)(NO)H 1.669 0.021 0.042 −0.012 0.011 0.934 7.83.8 31. Mo(PH3)4(NO)H 1.665 0.026 0.043 −0.015 0.013 0.855 7.43.6 . − . 32. Mo(NO)(dpcp)2H1623 0.027 0.043 0 016 0 013 0 834 8 54.1 . − . 33. Mo(dpe)2(NO)H 1 627 0.027 0.042 0 016 0 013 0 834 8 64.2(2018) 130:98 . − . 34. Mo(dpe)(CO)2(NO)H 1 661 0.025 0.042 0 014 0 012 0 863 8 63.0 ( ) . − . 35. W(CO)2 PH3 2(NO)H 1 815 0.02 0.044 0 011 0 011 0 991 6 83.3 J. Chem. Sci. (2018) 130:98 Page 3 of 8 98 + N)] , [IrH3(PPh3)2(2-NH2C5H4N)], [Ir(PMe3)4(H) [ ( )( ) ] 2 (OH)] and Fe(H)2 H2 PEt2Ph 4 . In our previous study, the formation of Ru–H···H–O kcal/mol ) type DHB complex is invoked to explain the mechanism sol ( 22 int of water splitting ability of Milstein catalyst and sev- eral other studies showed that increasing the hydricity of M–H bond is attractive for designing water splitting reactions of metal hydride complexes. 17–20 In a recent study, we showed that hydricity of several group VI and 93.4 74.1 34.4 83.1 53.6 . group VII octahedral metal hydride complexes of Mo, kcal/mol E W, Mn, and Re complexes can be quantified from the int electrostatic potential minimum observed on the hydride ligand. 23 These studies suggest that the M–H···H–O DHB interaction and the associated H2 elimination reac- au E c tion is intimately connected with the nature of H···H V 886 7 855 8 837 9 03 6 882 7 / .
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