Synthesis and Structural Characterization of Novel Neutral Hexacoordinate Silicon(IV) Complexes with SiO_2N_4 Skeletons Containing Cyanato-N or Thiocyanato-N Ligands

摘要

A series of novel hexacoordinate silicon(IV) complexes with an SiO_2N_4 skeleton (compounds (OC-6-12)-3,(OC-6-12)-4,(OC-6-12)-5,(OC-6-12)-6,and (OC-6-2'2)-7) were synthesized,starting from Si(NCO)_4 or Si(NCS)_4.These compounds contain (i) two bidentate O,N-chelate ligands (or one tetradentate O,N,N,O-chelate ligand) derived from 4-aminopent-3-en-2-ones of the formula type Me-C(NRH)=CH-C(O)-Me (R=organyl) and (ii) two monodentate cyanato-N or thiocyanato-N ligands.Formally,the bidentate singly negatively charged O,N-chelate ligands (tetradentate 2-fold negatively charged O,N,N,O-chelate ligand) behave as ligands of the imino-enolato type.In addition,the adduct trans-8 was synthesized by reaction of Si(NCS)_4 with 2 molar equiv of Me-C(Ni-PrH)=CH-C(O)-Me.This hexacoordinate silicon(IV) complex contains (i) four monodentate thiocyanato-N ligands and (ii) two neutral monodentate ligands of the iminio-enolato type.All compounds synthesized were structurally characterized by single-crystal X-ray diffraction and solid-state and solution NMR spectroscopy.To get more information about the stereochemistry of these compounds,the experimental investigations were complemented by computational studies.