Knowledge Bank

The high resolution rotational spectra of $(CH3)314NAIH3,(CH3)315NAIH3(CH3)314NAID2(CH3)314NAIHD2$ and $(CH3)314NAIH2D$ are reported using a recently constructed pulsed-nozzle Fourier-transform microwave spectrometer. The $\mathrm{<mrow\; data-mjx-texclass="ORD">27</mrow>}$Al and $\mathrm{<mrow\; data-mjx-texclass="ORD">14</mrow>}N$ hyperfine structure in $(CH3)314NAIH3$ and $(CH3)314NAID3$ have been fit to a standard Hamiltonian for two quadrupolar nuclei. The analysis for $(CH3)314NAIH3$ gives $B=2475.113(1) MHz, D_{J} = 643(4) Hz, D_{JK} = 1372(250) $Hz, $eQq(27Al)=25.032(6)$ MHz and $eQq(14N)=-3.777(5)$ 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 $\mathrm{<mrow\; data-mjx-texclass="ORD">27</mrow>}$Al nuclear quadrupole coupling constant in a polyatomic aluminum compound. The aluminum-nitrogen bond distance and $eQq(27Al)$ are related to the dissociation energy of the dative bond in $(CH3)3NAIH3$. Comparisons are also made with analogous boron-nitrogen donor-acceptor complexes.