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1. Binding energies of hydrated cobalt( ii ) by collision-induced dissociation and theoretical studies: evidence for a new critical size

   https://doi.org/10.1039/C7CP05828D  

   Coates, Rebecca A.; Armentrout, P. B. (January 2018, Physical Chemistry Chemical Physics)

   The experimental sequential bond energies for loss of water from Co 2+ (H 2 O) x complexes, x = 5–11, are determined by threshold collision-induced dissociation (TCID) using a guided ion beam tandem mass spectrometer with a thermal electrospray ionization source. Kinetic energy dependent TCID cross sections are analyzed to yield 0 K thresholds for sequential loss of neutral water molecules. The thresholds are converted from 0 to 298 K values to give hydration enthalpies and free energies. Theoretical geometry optimizations and single point energy calculations at several levels of theory are performed for the reactant and product ion complexes. Theoretical bond energies for ground structures are used for direct comparison with experimental values to obtain structural information on these complexes. In addition, the dissociative charge separation process, Co 2+ (H 2 O) x → CoOH + (H 2 O) m + H + (H 2 O) x−m−1 , is observed at x = 4, 6, and 7 in competition with primary water loss products. Energies for the charge separation rate-limiting transition states are calculated and compared to experimental threshold measurements. Results suggest that the critical size for which charge separation is energetically favored over water loss is x crit = 6, in contrast to lower values in previous literature reports. 

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2. Ionization energies and cationic bond dissociation energies of RuB, RhB, OsB, IrB, and PtB

   https://doi.org/10.1063/5.0107086  

   Merriles, Dakota M.; Morse, Michael D. (August 2022, The Journal of Chemical Physics)

   Two-photon ionization thresholds of RuB, RhB, OsB, IrB, and PtB have been measured using resonant two-photon ionization spectroscopy in a jet-cooled molecular beam and have been used to derive the adiabatic ionization energies of these molecules. From the measured two-photon ionization thresholds, IE(RuB) = 7.879(9) eV, IE(RhB) = 8.234(10) eV, IE(OsB) = 7.955(9) eV, IE(IrB) = 8.301(15) eV, and IE(PtB) = 8.524(10) eV have been assigned. By employing a thermochemical cycle, cationic bond dissociation energies of these molecules have also been derived, giving D0(Ru+–B) = 4.297(9) eV, D0(Rh+–B) = 4.477(10) eV, D0(Os–B+) = 4.721(9) eV, D0(Ir–B+) = 4.925(18) eV, and D0(Pt–B+) = 5.009(10) eV. The electronic structures of the resulting cationic transition metal monoborides (MB+) have been elucidated using quantum chemical calculations. Periodic trends of the MB+ molecules and comparisons to their neutral counterparts are discussed. The possibility of quadruple chemical bonds in all of these cationic transition metal monoborides is also discussed. 

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3. Streams, cascades, and pools: various water cluster motifs in structurally similar Ni( ii ) complexes

   https://doi.org/10.1039/C8CE01153B  

   Saraei, Nina; Hietsoi, Oleksandr; Mullins, Christopher S.; Gupta, Alexander J.; Frye, Brian C.; Mashuta, Mark S.; Buchanan, Robert M.; Grapperhaus, Craig A. (November 2018, CrystEngComm)

   Hydrogen bonding (HB) interactions are well known to impact the properties of water in the bulk and within hydrated materials. A series of Ni( ii ) complexes based on chelates containing N -(2-aminoethyl)-1-methylimidazole-2-carboxamide have been synthesized and fully characterized by single crystal X-ray diffraction, spectroscopic methods, and thermal analysis. The complexes reveal a variety of water cluster motifs dependent on the packing arrangement in the solid state. A key feature is the orientation of the carboxamide moiety, which leads to the formation of void spaces that accommodate water through HB interactions. The water motifs contain 1D water chains (streams), 2D tapes of infused rings (cascades), and isolated water dimers (pools). The HB motifs in the hydrated structures vary as a function of the crystal packing of the host molecules. Thermal analyses show a correlation between the HB motif in the hydrated crystals and the temperature range of the dehydration process. The conductivity of the hydrated crystals varies as a function of the crystal packing interactions between metal complexes. 

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4. Copper( i ) and silver( i ) chemistry of vinyltrifluoroborate supported by a bis(pyrazolyl)methane ligand

   https://doi.org/10.1039/d1dt00974e  

   Zacharias, Adway O.; Mao, James X.; Nam, Kwangho; Dias, H. V. (June 2021, Dalton Transactions)

   null (Ed.)

   Although unsaturated organotrifluoroborates are common synthons in metal–organic chemistry, their transition metal complexes have received little attention. [CH 2 (3,5-(CH 3 ) 2 Pz) 2 ]Cu(CH 2 CHBF 3 ), (SIPr)Cu(MeCN)(CH 2 CHBF 3 ) and [CH 2 (3,5-(CH 3 ) 2 Pz) 2 ]Ag(CH 2 CHBF 3 ) represent rare, isolable molecules featuring a vinyltrifluoroborate ligand on coinage metals. The X-ray crystal structures show the presence of three-coordinate metal sites in these complexes. The vinyltrifluoroborate group binds asymmetrically to the metal site in [CH 2 (3,5-(CH 3 ) 2 Pz) 2 ]M(CH 2 CHBF 3 ) (M = Cu, Ag) with relatively closer M–C(H) 2 distances. The computed structures of [CH 2 (3,5-(CH 3 ) 2 Pz) 2 ]M(CH 2 CHBF 3 ) and M(CH 2 CHBF 3 ), however, have shorter M–C(H)BF 3 distances than M–C(H) 2 . These molecules feature various inter- or intra-molecular contacts involving fluorine of the BF 3 group, possibly affecting these M–C distances. The binding energies of [CH 2 CHBF 3 ] − to Cu + , Ag + and Au + have been calculated at the wB97XD/def2-TZVP level of theory, in the presence and absence of the supporting ligand CH 2 (3,5-(CH 3 ) 2 Pz) 2 . The calculation shows that Au + has the strongest binding to the [CH 2 CHBF 3 ] − ligand, followed by Cu + and Ag + , irrespective of the presence of the supporting ligand. However, in all three metals, the supporting ligand weakens the binding of olefin to the metal. The same trends were also found from the analysis of the σ-donation and π-backbonding interactions between the metal fragment and the π and π* orbitals of [CH 2 CHBF 3 ] − . 

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5. Bond Dissociation Energies of RuC, RhC, OsC, IrC, and PtC Measured by Resonant Three-Photon Ionization Spectroscopy

   https://doi.org/10.1021/acs.jpca.5c04466  

   Tomchak, Kimberly H; Morse, Michael D (September 2025, The Journal of Physical Chemistry A)

   Resonant three-photon ionization spectroscopy has been used to study the late 4d and 5d transition metal carbides RuC, RhC, OsC, IrC, and PtC. These species, like most diatomic transition metals with open nd subshells, exhibit an exceptionally high density of states near the ground separated atom limit. Spin-orbit and nonadiabatic interactions provide a means for the molecules to rapidly dissociate as soon as the bond dissociation energy (BDE) is exceeded. The result is a sharp predissociation threshold that is identified as the BDE. The high BDEs of these five molecules required the use of two tunable lasers to reach the BDE. Measured values of D0(RuC) = 6.312(2) eV, D0(RhC) = 6.007(2) eV, D0(OsC) = 6.427(2) eV, D0(IrC) = 6.404(2) eV, and D0(PtC) = 6.260(2) eV were obtained, where the value is parentheses represents the estimated error limit in units of the last quoted digit. A new electronic state of PtC, tentatively assigned as the c(_^3)Σ_1^+ state, has been found with T0 = 22442 cm-1. These BDEs are combined with recently measured ionization energies to obtain BDEs of the associated cations. Electronic structure calculations are also reported to investigate the chemical bonding in more detail. Trends in the BDEs of the diatomic transition metal carbides are also discussed. 

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