Experimental Gas-Phase Thermochemistry for Alkane Reductive Elimination from Pt(IV)

The gas-phase reactivity of the [(NN)PtIVMe3]+ (NN = α-diimine) complex 1 and its acetonitrile adduct has been investigated by tandem mass spectrometry. The only observed reaction from the octahedral d6 complex 1·MeCN is the simple dissociation of the coordinated solvent molecule with a binding energy of 24.5(6) kcal mol–1 measured by energy-resolved collision-induced dissociation experiments. Further reactions of 1 are observed. In addition to the expected reductive elimination of ethane from 1, competitive loss of methane occurs. Methane is generated from the initially formed ethane agostic complex via either C–H activation/bond formation or σ-bond metathesis with the third methyl group. Energy-resolved collision-induced dissociation experiments indicate that the initial reductive C–C coupling step is rate limiting for both ethane and methane elimination, and afford a gas-phase barrier of 22.6(7) kcal mol–1 for this process. Density functional theory calculations confirm the reaction mechanisms, and a v...

[1]  R. Bergman,et al.  Selective Intermolecular Carbon-Hydrogen Bond Activation by Synthetic Metal Complexes in Homogeneous Solution , 1995 .

[2]  S. Grimme,et al.  A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT-D) for the 94 elements H-Pu. , 2010, The Journal of chemical physics.

[3]  J. Bercaw,et al.  Hydrogen tunneling in protonolysis of platinum(II) and palladium(II) methyl complexes: mechanistic implications. , 2008, Journal of the American Chemical Society.

[4]  A. Bach,et al.  Simple fitting of energy-resolved reactive cross sections in threshold collision-induced dissociation (T-CID) experiments. , 2007, The journal of physical chemistry. A.

[5]  M. Bowers,et al.  Multiple transition states in unimolecular reactions: A transition state switching model. Application to the C4H8 +⋅ system , 1981 .

[6]  A. Johansson,et al.  Mechanistic Investigation of Benzene C−H Activation at a Cationic Platinum(II) Center: Direct Observation of a Platinum(II) Benzene Adduct , 2000 .

[7]  Amir Karton,et al.  Benchmark study of DFT functionals for late-transition-metal reactions. , 2006, The journal of physical chemistry. A.

[8]  P. Armentrout,et al.  Translational energy dependence of Ar++XY→ArX++Y (XY=H2,D2,HD) from thermal to 30 eV c.m. , 1985 .

[9]  D. Truhlar,et al.  The M06 suite of density functionals for main group thermochemistry, thermochemical kinetics, noncovalent interactions, excited states, and transition elements: two new functionals and systematic testing of four M06-class functionals and 12 other functionals , 2008 .

[10]  G. Ellison,et al.  Three methods to measure RH bond energies , 1994 .

[11]  W. B. Almeida,et al.  The role of the basis set and the level of quantum mechanical theory in the prediction of the structure and reactivity of cisplatin , 2012, J. Comput. Chem..

[12]  Peter Chen,et al.  Experimental and theoretical study of a gold(I) aminonitrene complex in the gas phase. , 2010, Chemphyschem : a European journal of chemical physics and physical chemistry.

[13]  H. Amariglio,et al.  Conversion of methane into higher hydrocarbons on platinum , 1991, Nature.

[14]  R. Puddephatt,et al.  Mechanism of reductive elimination of ethane from some halogenotrimethylbis(tertiary phosphine)platinum(IV) complexes , 1975 .

[15]  Zhenyang Lin,et al.  Current understanding of the σ-bond metathesis reactions of LnMR + R′–H → LnMR′ + R–H , 2007 .

[16]  Jan M.L. Martin,et al.  Correlation consistent valence basis sets for use with the Stuttgart–Dresden–Bonn relativistic effective core potentials: The atoms Ga–Kr and In–Xe , 2001 .

[17]  R. Asselt,et al.  Stabilization of high oxidation states by rigid bidentate nitrogen ligands: synthesis and characterization of diorgano- and triorganopalladium(IV) and cationic triorganoplatinum(IV) complexes , 1994 .

[18]  Donald G Truhlar,et al.  Density functionals for inorganometallic and organometallic chemistry. , 2005, The journal of physical chemistry. A.

[19]  A. Fedorov,et al.  Gas-phase synthesis and reactivity of a gold carbene complex. , 2008, Journal of the American Chemical Society.

[20]  C. E. Webster,et al.  Experimental and computational evidence for a boron-assisted, sigma-bond metathesis pathway for alkane borylation. , 2003, Journal of the American Chemical Society.

[21]  A. Bach,et al.  Transmetalation supported by a Pt(II)-Cu(I) bond. , 2010, Angewandte Chemie.

[22]  A. Canty.  Development of organopalladium(IV) chemistry: fundamental aspects and systems for studies of mechanism in organometallic chemistry and catalysis , 1992 .

[23]  K. I. Goldberg,et al.  Mechanisms of C-C and C-H alkane reductive eliminations from octahedral Pt(IV): reaction via five-coordinate intermediates or direct elimination? , 2003, Journal of the American Chemical Society.

[24]  J. Bercaw,et al.  C [bond] H activation by cationic platinum(II) complexes: ligand electronic and steric effects. , 2002, Journal of the American Chemical Society.

[25]  Peter Chen,et al.  Interaction of organoplatinum(II) complexes with monovalent coinage metal triflates. , 2009, Journal of the American Chemical Society.

[26]  Donald G Truhlar,et al.  Design of Density Functionals by Combining the Method of Constraint Satisfaction with Parametrization for Thermochemistry, Thermochemical Kinetics, and Noncovalent Interactions. , 2006, Journal of chemical theory and computation.

[27]  E. Baerends,et al.  Analysis of nondynamical correlation in the metal–ligand bond. Pauli repulsion and orbital localization in MnO−4 , 1990 .

[28]  Peter Chen,et al.  Gas-phase thermochemistry of ruthenium carbene metathesis catalysts. , 2008, Journal of the American Chemical Society.

[29]  W. Kaminsky,et al.  A stable five-coordinate platinum(IV) alkyl complex. , 2001, Journal of the American Chemical Society.

[30]  J. Bercaw,et al.  Exploring the Mechanism of Aqueous C−H Activation by Pt(II) through Model Chemistry: Evidence for the Intermediacy of Alkylhydridoplatinum(IV) and Alkane σ-Adducts , 1996 .

[31]  A. A. Shteinman,et al.  Activation of saturated hydrocarbons by metal complexes in solution , 1977 .

[32]  Peter Chen,et al.  Transmetalation of methyl groups supported by Pt(II)-Au(I) bonds in the gas phase, in silico, and in solution. , 2011, Journal of the American Chemical Society.

[33]  M. Jarrold,et al.  Unimolecular and bimolecular reactions in the C6H6+· system. Experiment and theory , 1984 .

[34]  Peter Chen,et al.  Ligand Binding Energies in Cationic Platinum(II) Complexes: A Quantitative Study in the Gas Phase , 2007 .

[35]  H. Schwarz,et al.  Thermal C−H Bond Activation of Benzene, Toluene, and Methane with Cationic [M(X)(bipy)]+ (M = Ni, Pd, Pt; X = CH3, Cl; bipy = 2,2′-bipyridine): A Mechanistic Study , 2011 .

[36]  Stefan Grimme,et al.  Effect of the damping function in dispersion corrected density functional theory , 2011, J. Comput. Chem..

[37]  P. Armentrout.  Mass spectrometry—Not just a structural tool: The use of guided ion beam tandem mass spectrometry to determine thermochemistry , 2002, Journal of the American Society for Mass Spectrometry.

[38]  P. Armentrout.  The Power of Accurate Energetics (or Thermochemistry: What is it Good for?) , 2013, Journal of The American Society for Mass Spectrometry.

[39]  J. G. Vries.  A unifying mechanism for all high-temperature Heck reactions. The role of palladium colloids and anionic species , 2006 .

[40]  D. Truhlar,et al.  A new local density functional for main-group thermochemistry, transition metal bonding, thermochemical kinetics, and noncovalent interactions. , 2006, The Journal of chemical physics.

[41]  R. Perutz,et al.  The σ‐CAM Mechanism: σ Complexes as the Basis of σ‐Bond Metathesis at Late‐Transition‐Metal Centers , 2007 .

[42]  P. Armentrout,et al.  Statistical rate theory and kinetic energy-resolved ion chemistry: theory and applications. , 2008, The journal of physical chemistry. A.

[43]  D. Blake,et al.  Thermochemistry of the oxidative addition reaction , 1982 .

[44]  P. Siegbahn,et al.  The effect of electron correlation on the metal-ligand interaction in iron pentacarbonyl (Fe(CO)5) , 1985 .

[45]  Donald G. Truhlar,et al.  Adiabatic connection for kinetics , 2000 .

[46]  R. Ettorre.  Mechanism of reductive elimination from an aryl derivative of platinum(IV) , 1969 .

[47]  K. I. Goldberg,et al.  Mechanistic information on the reductive elimination from cationic trimethylplatinum(IV) complexes to form carbon-carbon bonds. , 2005, Inorganic chemistry.

[48]  E. Keinan,et al.  TpPtMe(H)(2): why is there H/D scrambling of the methyl group but not methane loss? , 2002, Journal of the American Chemical Society.

[49]  P. Armentrout.  Threshold Collision-Induced Dissociations for the Determination of Accurate Gas-Phase Binding Energies and Reaction Barriers , 2003 .

[50]  M. Jarrold,et al.  Kinetics of ion–molecule collision complexes in the gas phase. Experiment and theory , 1983 .

[51]  Peter Chen,et al.  Structure and bonding of isoleptic coinage metal (Cu, Ag, Au) dimethylaminonitrenes in the gas phase. , 2010, Journal of the American Chemical Society.

[52]  M. Hall,et al.  Carbon-hydrogen bond activation: two, three, or more mechanisms? , 2007, Journal of the American Chemical Society.

[53]  J. Bercaw,et al.  Large Kinetic Isotope Effects for the Protonolysis of Metal–Methyl Complexes Are Not Reliable Mechanistic Indicators , 2011 .

[54]  Xiangyang Zhang,et al.  A quantitative study of intrinsic non-covalent interactions within complexes of α-cyclodextrin and benzoate derivatives. , 2012, Chemical communications.

[55]  Donald G Truhlar,et al.  Density functionals with broad applicability in chemistry. , 2008, Accounts of chemical research.

[56]  Xiaosong Li,et al.  Energy-Represented Direct Inversion in the Iterative Subspace within a Hybrid Geometry Optimization Method. , 2006, Journal of chemical theory and computation.

[57]  Peter Hofmann,et al.  Inter- and Intramolecular Interactions in Triptycene-Derived Bisphosphite Hydroformylation Catalysts: Structures, Energies, and Caveats for DFT-Assisted Ligand Design , 2013 .

[58]  Peter Chen,et al.  Threshold CID investigation of isomeric Cu(I) azabox complexes. , 2007, Inorganic chemistry.

[59]  Peter Chen,et al.  Co-C bond energies in adenosylcobinamide and methylcobinamide in the gas phase and in silico. , 2013, Journal of the American Chemical Society.

[60]  Peter Chen,et al.  Energy-resolved collision-induced dissociation cross sections of 2:1 bis-oxazoline copper complexes. Nonbonded interactions and nonlinear effects. , 2007, Journal of the American Chemical Society.

[61]  R. Puddephatt,et al.  Reactivity and mechanism in oxidative addition to palladium(II) and reductive elimination from palladium(IV) and an estimate of the palladium methyl bond energy , 1988 .

[62]  Peter Chen,et al.  Gas-phase energetics of reductive elimination from a palladium(II) N-heterocyclic carbene complex. , 2010, Chemistry.

[63]  J. Collman,et al.  Oxidative-Addition Reactions of d8 Complexes , 1969 .

[64]  O. Eisenstein,et al.  C-H bond activation in transition metal species from a computational perspective. , 2010, Chemical reviews.

[65]  G. B. Shul’pin,et al.  ACTIVATION OF C-H BONDS BY METAL COMPLEXES , 1997 .

[66]  R. Crabtree.  Transition Metal Complexation of σ Bonds , 1993 .