Structural Characterization of Paramagnetic Octahedral Homoscor‐Pionate (Polypyrazolylborate) Cobalt Complexes by 1H and 13C NMR Spectroscopy and by FAB‐Mass Spectrometry

1H and 13C NMR spectroscopy as well as the FAB mass spectrometry have been applied to six bis[tris(pyrazol-1-yl)borates]Co(ll) and one bis[tetrakis(pyrazol-1-yl)borate]Co(ll). These octahedral complexes are paramagnetic and it was therefore very difficult to obtain their 13C NMR. The isotropic shifts are very large and characteristic of the different positions of the pyrazole and the boron substituents. FAB-MS also is an interesting method to characterize these complexes, since they give abundant molecular ions and specific fragmentation.

[1]  M. Takayama,et al.  Competitive formation of M+. and [M+H]+ ions under fast atom bombardment conditions , 1993 .

[2]  S. Trofimenko.  Recent advances in poly(pyrazolyl)borate (scorpionate) chemistry , 1993 .

[3]  J. Calabrese,et al.  Hydrotris(3-neopentylpyrazol-1-yl)borates: a new type of sterically hindered poly(pyrazolyl)borates , 1992 .

[4]  Jean Martínez,et al.  Dehydroxylation reaction induced by the matrix in the fast atom bombardment mass spectra of a peptide , 1992 .

[5]  P. Domaille,et al.  Hydrotris[3-(2'-thienyl)pyrazol-1-yl]borate : a ligand of remarkably low steric requirements , 1991 .

[6]  J. Reedijk,et al.  Spectroscopic and magnetic properties of square-planar bis[(cyclooctane-1,5-diyl)bis(pyrazol-1-yl)borato]cobalt(II) , 1991 .

[7]  P. Arpino.  Combined liquid chromatography mass spectrometry. Part II. Techniques and mechanisms of thermospray , 1990 .

[8]  J. Elguero,et al.  Structure of bis-, tris- and tetrakispyrazolylborates in the solid state (sodium and potassium salts of tetrakispyrazolylborate by X-ray crystallography) and in solution (1H, 11B, 13C and 15N NMR) , 1990 .

[9]  P. Domaille,et al.  Steric effects in polypyrazolylborates : mixed complexes M(HB(3-isopropyl-4-bromopyrazolyl)3)L , 1990 .

[10]  P. Vouros,et al.  Reduction processes in fast atom bombardment mass spectrometry: interdependence of analyte and matrix redox potentials. , 1990, Biomedical & environmental mass spectrometry.

[11]  Jack M. Miller.  Fast atom bombardment mass spectrometry (FAB MS) of organometallic, coordination, and related compounds , 1990 .

[12]  K. D. Cook,et al.  Improving fast atom bombardment mass spectra: The influence of some controllable parameters on spectral quality , 1990, Journal of the American Society for Mass Spectrometry.

[13]  P. Domaille,et al.  Steric effects in polypyrazolylborate ligands. Poly(3-isopropylpyrazolyl)borates: ligands of intermediate steric requirements , 1989 .

[14]  Stephen A. Martin,et al.  Mass spectrometric determination of the amino acid sequence of peptides and proteins , 1987 .

[15]  K. Schram,et al.  Fast atom Bombardment Mass Spectrometry of Nucleosides, Nucleotides and Oligonucleotides , 1985 .

[16]  P. Domaille,et al.  ULTRA-HIGH FIELD NMR SPECTROSCOPY: OBSERVATION OF PROTON-PROTON DIPOLAR COUPLING IN PARAMAGNETIC BIS(TOLYLTRIS(PYRAZOLYL)BORATO)COBALT(II) , 1981 .

[17]  P. Domaille.  Direct measurement of the electron susceptibility anisotropy in paramagnetic complexes using high-field deuterium NMR , 1980 .

[18]  P. Meakin,et al.  Theories of the isotropic shift in complexes with T ground states. Experimental test , 1971 .

[19]  S. Trofimenko.  Boron-pyrazole chemistry. IV. Carbon- and boron-substituted poly[(1-pyrazolyl) borates] , 1967 .

[20]  J. Jesson.  Isotropic Nuclear Resonance Shifts in Some Trigonal Co(II) and Ni(II) Chelate Systems , 1967 .

[21]  J. Jesson,et al.  Spectra and structure of some transition metal poly(1-pyrazolyl) borates , 1967 .

[22]  R. Singh,et al.  A study of reduction phenomena in a high performance liquid chromatography/particle beam/mass spectrometer system , 1995 .

[23]  R. Nesper,et al.  .kappa.2-.kappa.3 Isomerism in Rhodium(I) Tris(pyrazolyl)borate Complexes of the Type Tp3R,4R,5RRh(LL) (LL = 2CO, COD, and NBD) and Their Dynamic Behavior in Solution. X-ray Crystal Structure of TpMeRh(NBD) , 1995 .

[24]  J. Aubagnac,et al.  Reduction phenomenon in the fast atom bombardment mass spectra of cyclotetrapeptide analogues of chlamydocin , 1993 .

[25]  K. Itoh,et al.  Application of FRIT fast atom bombardment liquid chromatography/mass spectrometry for the determination of acetylcholine levels in rat brain regions. , 1991, Biological mass spectrometry.

[26]  P. Arpino.  Combined liquid chromatography mass spectrometry. Part I. Coupling by means of a moving belt interface , 1989 .

[27]  Michael Barber,et al.  Fast atom bombardment of solids (F.A.B.): a new ion source for mass spectrometry , 1981 .