ROTATIONAL SPECTRA, $^{27}AL$ AND $^{14}N$ NUCLEAR QUADRUPOLE COUPLING CONSTANTS AND MOLECULAR STRUCTURE OF TRIMETHYLAMINE ALANE $(CH_{3})_{3}NALH_{3}$
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Date
1994
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Ohio State University
Abstract
The high resolution rotational spectra of $(CH_{3})_{3}^{14}NAIH_{3}, (CH_{3})_{3}^{15}NAIH_{3} (CH_{3})_{3}^{14}NAID_{2} (CH_{3})_{3}^{14}NAIHD_{2}$ and $(CH_{3})_{3}^{14}N AIH_{2}D$ are reported using a recently constructed pulsed-nozzle Fourier-transform microwave spectrometer. The $^{27}$Al and $^{14} N$ hyperfine structure in $(CH_{3})_{3}^{14}NAIH_{3}$ and $(CH_{3})_{3} ^{14} NAID_{3}$ have been fit to a standard Hamiltonian for two quadrupolar nuclei. The analysis for $(CH_{3})_{3}^{14} NAIH_{3}$ gives $B=2475.113(1) MHz, D_{J} = 643(4) Hz, D_{JK} = 1372(250) $Hz, $eQq(27Al) = 25.032(6)$ MHz and $eQq(^{14}N) = -3.777(5)$ MHz. A combination of all the microwave isotopic moments of intertia with an electron diffraction study determines the complete molecular structure. This work provides the first measurement of a gas phase $^{27}$Al nuclear quadrupole coupling constant in a polyatomic aluminum compound. The aluminum-nitrogen bond distance and $eQq(^{27}Al)$ are related to the dissociation energy of the dative bond in $(CH_{3})_{3}NAIH_{3}$. Comparisons are also made with analogous boron-nitrogen donor-acceptor complexes.
Description
1. A. Almenningen, G. Gundersen, T. Haugen and A. Haaland, Act Chem. Scand. 26, 3928 (1972).
Author Institution: Department of Chemistry, Rensselaer Polytechnic Institute; Department of Physics, Cornell University; Department of Chemistry, Rensselaer Polytechnic Institute
Author Institution: Department of Chemistry, Rensselaer Polytechnic Institute; Department of Physics, Cornell University; Department of Chemistry, Rensselaer Polytechnic Institute