Ab initio calculations of the properties of simple alkali and alkaline earth organometallics

Abstract A systematic study is reported on the properties of a series of simple organometallic compounds of the type MR, where M is either an alkali (Li, Na, K) or alkaline earth (Be, Mg, Ca) metal atom and R is one of the organic substituents CH, CH 2 or CH 3 . Electronic structures, equilibrium geometries and dipole moments have been calculated at the SCF and MP2 levels of theory using quite large basis sets. Rather accurate MC bond dissociation energies have also been obtained by exploiting the highly ionic character of most of the molecules. This involved dissociating to the ionic limit and then employing experimental data to correct to the neutral dissociation limit. The good agreement between SCF and MP2 values obtained by this method leads us to conclude that the calculated dissociation energies are at worst within 0.2 eV of the true values, and in most cases are probably accurate to within 0.1 eV.

[1]  C. Bauschlicher,et al.  Theoretical study of the diatomic alkali and alkaline-earth oxides , 1986 .

[2]  G. Corlett,et al.  SPECTROSCOPIC INVESTIGATION OF ZINC-CONTAINING ORGANOMETALLIC RADICALS PREPARED USING A PULSED ELECTRICAL DISCHARGE NOZZLE , 1994 .

[3]  J. Pople,et al.  Carbon-beryllium binding in CH2Be , 1977 .

[4]  P. Bernath,et al.  The à 2E–X̃ 2A1 transition of monomethyl calcium: A rotational analysis , 1989 .

[5]  P. Schleyer,et al.  "Inverted" Sodium-Lithium Electronegativity: Polarity and Metalation Energies of Organic and Inorganic Alkali-Metal Compounds , 1993 .

[6]  Lester Andrews,et al.  Infrared Spectrum of Methyl Lithium Monomer in Solid Argon , 1967 .

[7]  A. J. Downs,et al.  Characterisation of monomeric methylsodium and methylpotassium: infrared spectra of the matrix-isolated molecules , 1990 .

[8]  C. Bauschlicher,et al.  Ab initio study of the alkali and alkaline‐earth monohydroxides , 1986 .

[9]  Krishnan Raghavachari,et al.  Methyllithium and its oligomers. Structural and energetic relationships , 1988 .

[10]  A. Streitwieser,et al.  Ab initio SCF-MO calculations of methyllithium and related systems. Absence of covalent character in the carbon-lithium bonds , 1976 .

[11]  A. Ellis,et al.  Electronic spectroscopy of jet-cooled half-sandwich magnesium organometallic complexes MgC5H5, MgC5H4CH3, and MgC4H4N , 1992 .

[12]  J. Chandrasekhar,et al.  A theoretical survey of unsaturated or multiply bonded and divalent silicon compounds. Comparison with carbon analogs , 1986 .

[13]  W. C. Lineberger,et al.  Methylene: A study of the X̃ 3B1 and ã 1A1 states by photoelectron spectroscopy of CH−2 and CD−2 , 1985 .

[14]  Hans W. Horn,et al.  Fully optimized contracted Gaussian basis sets for atoms Li to Kr , 1992 .

[15]  V. Bondybey,et al.  Pulsed discharge source of supersonically cooled transient species , 1991 .

[16]  A. Ellis,et al.  Spectroscopy of jet‐cooled metal–monocyclopentadienyl complexes: Laser excitation spectra of calcium and cadmium cyclopentadienides , 1991 .

[17]  M. Maestro,et al.  Ab initio calculations for ground states of CH2Li− and CH2Be , 1974 .

[18]  M. Guest,et al.  A theoretical study of the bonding in methyllithium, trimethylborane and dimethylzinc , 1972 .

[19]  J. Pople,et al.  Molecular orbital theory of the electronic structure of molecules. 34. Structures and energies of small compounds containing lithium or beryllium. Ionic, multicenter, and coordinate bonding , 1977 .

[20]  Peter R. Taylor,et al.  The choice of Gaussian basis sets for molecular electronic structure calculations , 1981 .

[21]  W. C. Lineberger,et al.  Laser photoelectron spectrometry of CH , 1975 .

[22]  S. F. Boys,et al.  The calculation of small molecular interactions by the differences of separate total energies. Some procedures with reduced errors , 1970 .

[23]  B. Luke,et al.  A theoretical comparison of the lowest-lying singlet and triplet states of HCB and HBC , 1983 .

[24]  D. Arad,et al.  Structures and stabilities of α-hetero-substituted organolithium and organosodium compounds. Energetic unimportance of d-orbital effects , 1984 .

[25]  A. Balaban,et al.  On the Molecular Structure of Dimethylberyllium Monomer. , 1969 .

[26]  W. Lipscomb,et al.  Effects of basis set and configuration interaction on the electronic structure of methyllithium, with comments on the nature of the carbon-lithium bond , 1980 .

[27]  I. Shavitt.  Geometry and singlet−triplet energy gap in methylene: a critical review of experimental and theoretical determinations , 1985 .

[28]  S. Langhoff,et al.  On the 1A1–3B1 separation in CH2 and SiH2 , 1987 .

[29]  K. Meiwes-Broer,et al.  Pure metal and metal-doped rare-gas clusters grown in a pulsed ARC cluster ion source , 1990 .

[30]  R. Datta,et al.  The bonding, structure and energetics of LiCH3, HBeCH3, HBeNH2 and their dimers: Ab initio molecular orbital calculations , 1973 .

[31]  R. Ahlrichs,et al.  The C-Li bond in methyllithium. Binding energy and ionic character , 1986 .

[32]  T. Miller,et al.  High resolution electronic spectroscopy of MgCH3 , 1995 .

[33]  M. Yoshimine,et al.  A theoretical study of the electron affinity of methylene , 1989 .

[34]  W. C. Lineberger,et al.  An experimental determination of the geometry and electron affinity of methyl radical , 1978 .

[35]  S. Langhoff,et al.  Theoretical dissociation energies for the alkali and alkaline-earth monofluorides and monochlorides , 1986 .

[36]  Dietmar Seyferth,et al.  Comprehensive Organometallic Chemistry , 1984 .

[37]  P. Bernath,et al.  Observation of gas phase organometallic free radicals: Monomethyl derivatives of calcium and strontium , 1987 .

[38]  Bowen Liu,et al.  Valence excited states of CH. I. Potential curves , 1973 .

[39]  N. J. Fitzpatrick.  Comparative AB initio calculations on methylmetals , 1974 .