TY - JOUR
T1 - Microwave spectra, ab initio and DFT calculations and molecular structure for (η7-cycloheptatriene)Ti(η5-cyclopentadienyl) and (η7-cycloheptatriene)Cr(η5-cyclopentadienyl)
AU - Daly, Adam M.
AU - Lavin, Catherine M.
AU - Weidenschilling, Erika S.
AU - Holden, Alison M.
AU - Kukolich, Stephen G.
N1 - Funding Information:
This material is based upon work supported by the National Science Foundation under Grant Nos. CHE-0721505 and CHE-0809053 . We are very grateful to the NSF for providing funding for this research. We thank Michael Bühl for calling our attention to problems with the previous 47 Ti quadrupole coupling value. We are extremely grateful to Philip Bunker for his generous, expert help with theoretical and symmetry problems associated with analysis and understanding of molecular spectra.
PY - 2011/5
Y1 - 2011/5
N2 - Microwave spectra of 1-d-(η7-cycloheptatriene) 48Ti(η5-cyclopentadienyl) (CHT-Ti-Cp) and two singly substituted 13C isotopomers were measured and gas phase structural parameters were determined. Rotational transitions were also measured for (η7-cycloheptatriene)52Cr(η5- cyclopentadienyl). Rotational constants for the Ti complex were found to be A = 1720(4) MHz, B = 769.269(1) MHz and C = 766.131(1) MHz and for [ 13CC6H7-48Ti-C5H 5], A = 1773(2) MHz, B = 769.6931(4) MHz and C = 761.1789(5) MHz and for [1-d-C7H648TiC5H5] and A = 1270(5) MHz, B = 767.0142(9) MHz and C = 765.323(1) MHz for [C 7H748Ti13CC4H 5]. A structural analysis for the (CHT-Ti-Cp) data showed that the cycloheptatriene ring protons droop towards titanium as predicted by DFT and MP2 calculations. The droop of the protons toward the metal was experimentally determined to be 8.0(2)°out of the plane of the cycloheptatriene ring. The ring center distance to titanium was found to be 2.01(3) for Ti-Cp and 1.48(3) for Ti-CHT using a least squares fit to the measured rotational constants and fixing many of the structural parameters to the calculated values. The spectrum of the normal isotopomer (η7-cycloheptatriene) Ti(η5-cyclopentadienyl) was re-measured and a discussion of the possible 47Ti quadrupole coupling constants is presented. The chromium analog K = 0 spectrum was analyzed to obtain B = 851.229 MHz, and DJ = 0.028(6) kHz. Results from structure calculations are reported and discussed for (CHT-M-Cp) complexes with M = Ti, Cr, Zr, Hf, Mo, W using MP2, B3PW91 and B3LYP methods.
AB - Microwave spectra of 1-d-(η7-cycloheptatriene) 48Ti(η5-cyclopentadienyl) (CHT-Ti-Cp) and two singly substituted 13C isotopomers were measured and gas phase structural parameters were determined. Rotational transitions were also measured for (η7-cycloheptatriene)52Cr(η5- cyclopentadienyl). Rotational constants for the Ti complex were found to be A = 1720(4) MHz, B = 769.269(1) MHz and C = 766.131(1) MHz and for [ 13CC6H7-48Ti-C5H 5], A = 1773(2) MHz, B = 769.6931(4) MHz and C = 761.1789(5) MHz and for [1-d-C7H648TiC5H5] and A = 1270(5) MHz, B = 767.0142(9) MHz and C = 765.323(1) MHz for [C 7H748Ti13CC4H 5]. A structural analysis for the (CHT-Ti-Cp) data showed that the cycloheptatriene ring protons droop towards titanium as predicted by DFT and MP2 calculations. The droop of the protons toward the metal was experimentally determined to be 8.0(2)°out of the plane of the cycloheptatriene ring. The ring center distance to titanium was found to be 2.01(3) for Ti-Cp and 1.48(3) for Ti-CHT using a least squares fit to the measured rotational constants and fixing many of the structural parameters to the calculated values. The spectrum of the normal isotopomer (η7-cycloheptatriene) Ti(η5-cyclopentadienyl) was re-measured and a discussion of the possible 47Ti quadrupole coupling constants is presented. The chromium analog K = 0 spectrum was analyzed to obtain B = 851.229 MHz, and DJ = 0.028(6) kHz. Results from structure calculations are reported and discussed for (CHT-M-Cp) complexes with M = Ti, Cr, Zr, Hf, Mo, W using MP2, B3PW91 and B3LYP methods.
KW - Microwave
KW - Organometallic complex
KW - Structure measurements
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U2 - 10.1016/j.jms.2011.03.013
DO - 10.1016/j.jms.2011.03.013
M3 - Article
AN - SCOPUS:79958159810
SN - 0022-2852
VL - 267
SP - 172
EP - 177
JO - Journal of Molecular Spectroscopy
JF - Journal of Molecular Spectroscopy
IS - 1-2
ER -