Two successive steps of hypercoordination at tin: The gas-phase and solid-state structures of (N,N-dimethylaminoxy)trimethylstannane

Article abstract of DOI:10.1021/om990219q

Me₃SnONMe₂ has been prepared from trimethyltin chloride and O-lithio-N,N-dimethylhydroxylamine and characterized by IR and NMR spectroscopy, mass spectrometry, and elemental analysis. Its gas-phase molecular structure has been determined by electron diffraction augmented by restraints taken from ab initio calculations at the MP2/DZ(P) level of theory. A secondary interaction (Sn?N, 2.731(14) ?) between the tin and nitrogen atoms has been detected and makes MB₃SnONMe₂ the first partially hypercoordinate tin compound studied in the gas phase. A solid-state structure of Me₃SnONMe₂ has been determined by X-ray diffraction of an in situ grown single crystal. In the crystal lattice the coordination sphere of tin is further enlarged by a weak intermolecular Sn?O contact (2.998(10) ?) and a 4+2 coordination geometry is achieved, which can be deduced from that of a distorted trigonal bipyramid with one of the axial substituents replaced by the two weak contacts. Important geometry parameter values are as follows (gas/solid): Sn-O 2.006(3)/2.063(6) ?, O-N 1.468(6)/1.440(9) ?, Sn-C(in plane) 2.148(4)/2.163(14) ?, Sn-C(out of plane) 2.146(3)/ 2.062(9) and 2.185(10) ?, Sn-O-N 102.5(8)/101.5(4)°, O-Sn-C(in plane) 99.6(10)/99.7(4)°, O-Sn-C(out of plane) 108.1(6)/119.6(4)° and 116.6(4)°.