Synthesis and molecular structures of N, N-dimethylhydroxyl-amino-trichlorosilane and -germane

摘要

The compounds Cl_3SiONMe_2 and Cl_3GeONMe_2 have been prepared by reacting HONMe_2 with SiCl_4 and GeCl_4, 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, ~(13)C, ~(15)N, ~(17)O, ~(29)Si, by mass spectrometry and elemental analyses. The solid-state structure of Cl_3SiONMe_2 was determined by low-temperature X-ray crystallography. The molecular structures of Cl_3SiONMe_2 and Cl_3GeONMe_2 in the gas phase have been determined by analysis of electron diffraction data augmented by restraints derived from ab initio calculations (MP2/3-31G). The molecules adopt C_s symmetry. Important gas-phase geometry parameter values for Cl_3SiONMe_2 are: Si-O 1.623(3), Si-Cl_(in-plane)2.022(4), Si-Cl_(out-of-plane)2.024(2), O-N 1.479(6) A, Si-O-N 105.6(8), O-Si-Cl_(in-plane)104.2(3), O-Si-Cl_(out-of-plane) 113.7(2), for Cl_3GeONMe_2: Go_0 1.759(6), Ge-Cl_(in-plane)2.104(2), O-N 1.489(9) A, Ge-O-N 104.0(11), O-Ge-Cl_(in-plane)108.9(20), O-Ge-Cl_(out-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 Cl_3SiONMe_2 is weaker than those in H_3SiONMe_2 or ClH_2SiONMe-2, but stronger than that in Me_3SiON(CF_3)_2. Both compounds reveal stronger donor-acceptor interactions than the methyl analogues Me_3SiONMe_2