Synthesis and molecular structures of N,N-dimethylhydroxylamino-trichlorosilane and -germane†
The compounds Cl3SiONMe2 and Cl3GeONMe2 have been prepared by reacting HONMe2 with SiCl4 and GeCl4, respectively, in the presence of the auxiliary base 2,6-dimethylpyridine. Their identity was proven by gas-phase IR and solution NMR spectroscopy of the nuclei 1H, 13C, 15N, 17O, 29Si, by mass spectrometry and elemental analyses. The solid-state structure of Cl3SiONMe2 was determined by low-temperature X-ray crystallography. The molecular structures of Cl3SiONMe2 and Cl3GeONMe2 in the gas phase have been determined by analysis of electron diffraction data augmented by restraints derived from ab initio calculations (MP2/6-31G*). The molecules adopt Cs symmetry. Important gas-phase geometry parameter values for Cl3SiONMe2 are: Si–O 1.623(3), Si–Clin-plane 2.022(4), Si–Clout-of-plane 2.024(2), O–N 1.479(6) Å, Si–O–N 105.6(8), O–Si–Clin-plane 104.2(3), O–Si–Clout-of-plane 113.7(2)°, for Cl3GeONMe2: Ge–O 1.759(6), Ge–Clin-plane 2.104(4), Ge–Clout-of-plane 2.106(2), O–N 1.484(9) Å, Ge–O–N 104.0(11), O–Ge–Clin-plane 108.9(20), O–Ge–Clout-of-plane 111.6(12)°. The structural data are interpreted in terms of weak attractive interactions between the nitrogen donor and the silicon/germanium acceptor atoms. The results are discussed in comparison with other structural data from the literature: the donor–acceptor interaction in Cl3SiONMe2 is weaker than those in H3SiONMe2 or ClH2SiONMe2, but stronger than that in Me3SiON(CF3)2. Both compounds reveal stronger donor–acceptor interactions than the methyl analogues Me3SiONMe2.