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

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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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    . ~ Submitted to the Encyclopedia of Catalysis; http: //www.enccat.com/ July 2000 4 * BNL-67609 Isotope Methods in Homogeneous Catalysis R. Morris Bullock and Bruce R. Bender Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973-5000 and Department of Chemistry, The Scripps Research Institute, La Jolla, CA 92110 The use of isotope labels has had a Iimdamentally important role in the determination of mechanisms of homogeneously catalyzed reactions. Mechanistic data is valuable since it can assist in the design and rational improvement of homogeneous catalysts. There are several ways to use isotopes in mechanistic chemistry. Isotopes can be introduced into controlled experiments and “followed” where they go or don’t go; in this way, Libby, Calvin, Taube and others used isotopes to elucidate mechanistic pathways for very different, yet important chemistries. Another important isotope method is the study of kinetic isotope effects (KIEs) and equilibrium isotope effect (EIEs). Here the mere observation of where a label winds up is no longer enough – what matters is how much slower (or faster) a labeled molecule reacts than the unlabeled material. The most carefid studies essentially involve the measurement of isotope fractionation between a reference ground state and the transition state. Thus kinetic isotope effects provide unique data unavailable from other methods, since information about the transition state of a reaction is obtained. Because getting an experimental glimpse of transition states is really tantamount to understanding catalysis, kinetic isotope effects are very powerfid. Direct substitution of D for H (e.g., D2 vs. H2, or D+vs. H’_)and measurement of the rate of a catalytic reaction provides a determination of the kinetic deuterium isotope effect on the overall reaction.
  • A Semiempirical Potential Model for H-Terminated Functionalized Surface of Porous Silicon

    A Semiempirical Potential Model for H-Terminated Functionalized Surface of Porous Silicon

    Digest Journal of Nanomaterials and Biostructures Vol. 5, No 4, October-December 2010, p. 947-957 A SEMIEMPIRICAL POTENTIAL MODEL FOR H-TERMINATED FUNCTIONALIZED SURFACE OF POROUS SILICON A. IOANID, M. DIEACONU, S. ANTOHE Faculty of Physics, University of Bucharest, Bucharest-Magurele, Romania A semiempirical potential model for functionalized surface of porous silicon has been devised. Considering both the Lennard-Jones and electrostatic contributions for the silicon surface-water and water-water interactions, we have shown that it is probable a Si-H...H-O dihydrogen bond between silicon surface and the interfacial water molecule. Due to their - strong reducing character the (Si3)-H silyl anion behaves as an acceptor of proton. This non-conventional dihydrogen bond between silicon surface and interfacial water is competitive with the classical hydrogen bond of between interfacial water-water molecules so that reduces hydrophobicity of surface. (Received October 1, 2010; accepted October 26, 2010) Keywords: Functionalized surface, porous silicon, dihydrogen bond, silyl anion, hydrophobicity 1. Introduction Porous Silicon (PS) is a redutable biomaterial for devices with potential impact in biological and medical applications concerning detection, transport and interactions of the macromolecules, due to the great ratio surface/volume and to the amphoter (hydrophobic/ hidrophylic) properties of their functionalizated surface. Biocompatibility is the ability of a material to interface by adsorption of a layer of protein, with a biological environment without provoking a defence response. PS can be either a bioactive, a bioinert or a resorbable material, depending on the morphological, chemical and electrical characteristics of the surface layer and those of the biological environment in which it is inserted [1].
  • H2 Binding, Splitting, and Net Hydrogen Atom Transfer at a Paramagnetic Iron Complex

    H2 Binding, Splitting, and Net Hydrogen Atom Transfer at a Paramagnetic Iron Complex

    H2 Binding, Splitting, and Net Hydrogen Atom Transfer at a Paramagnetic Iron Complex Demyan E. Prokopchuk,‡,† Geoffrey M. Chambers,‡ Eric D. Walter,§ Michael T. Mock,‡à and R. Morris Bullock*,‡ ‡ Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, WA 99352, United States § Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99352, United States ABSTRACT: The reactivity of H2 with abundant transition metals is crucial for developing catalysts for energy storage in chemical bonds. While diamagnetic transition metal complexes that bind and split H2 have been extensively studied, paramagnetic complexes I + I+ that exhibit this behavior remain rare. We describe the reactivity of a square planar S = ½ Fe (P4N2) cation (Fe ) that reversibly binds H2/D2 in solution, exhibiting an inverse equilibrium isotope effect of KH2/KD2 = 0.58(4) at -5.0 °C. In the presence of excess H2, I + the dihydrogen complex Fe (H2) cleaves H2 at 25 °C in a net hydrogen atom transfer reaction to give the dihydrogen-hydride cation II + trans-Fe (H)(H2) . The proposed mechanism of H2 splitting involves both intra- and intermolecular steps, resulting in a mixed first- I+ III + and second-order rate law with respect to initial [Fe ]. The key intermediate is a paramagnetic dihydride complex, trans-Fe (H)2 , whose weak FeIII-H bond dissociation free energy (calculated BDFE = 44 kcal/mol) leads to bimetallic H-H homolysis, generating II + trans-Fe (H)(H2) . Reaction kinetics, thermodynamics, electrochemistry, EPR spectroscopy, and DFT calculations all support the proposed reaction mechanism. The coordination and reactivity of H2 ligands at diamagnetic transition metals has been intensely studied for decades.1 Recent efforts in sustainable energy have focused on using + - dihydrogen (H2) or protons/electrons (H /e ) as energy carriers that are interconverted using molecular electrocatalysts.2 The thermodynamic bias for electrocatalytic H production or the 2 Figure 1.