356524-07-7Relevant academic research and scientific papers
Synthesis and basic coordination properties of side-chain functionalized bis-phosphonio-benzophospholides
Gudat, Dietrich,Haep, Stefan,Bajorat, Volker,Nieger, Martin
, p. 1119 - 1127 (2001)
Salts containing bis-phosphonio-benzophospholide cations 2a-d with an additional donor site in one of the phosphonio-moieties were synthesized either via quaternisation of the Ph2P moiety in the neutral phosphonio-benzophospholide 3, or via ring-closure of the functionalized bisphosphonium ion 6. The Ph2P-substituted cation 2d formed chelate complexes [M(κ2P,P′-2d)(CO)n]+ with M(CO)n = Ni(CO)2, Fe(CO)3, Cr(CO)4. In the latter case, competition between formation of the chelate and a complex [Cr(κP-2d)2(CO)4]2+ was observed, and interpreted as a consequence of antagonism between the stabilizing chelate effect and destabilizing ligand-ligand repulsions. The formation of stable PdII and PtII complexes of 2 d suggests that the chelate effect may also overcome the kinetic inhibition which so far prevented isolation of complexes of these metals with bis-phosphonio-benzophospholides. The newly synthesized ligands and complexes were characterized by spectroscopic data, and an X-ray crystal structure analysis of 2a[Br]. The reactivity of chelate complexes towards Ph3P indicates that the ring phosphorus atom is a weaker donor than the pendant Ph2P-group. Wiley-VCH Verlag GmbH, 2001.
