Reactivity study of cyclopentadienyl osmium(II) bisphosphine azido complexes with activated alkynes and nitriles: Isolation of osmium triazolato and tetrazolato complexes by 1,3-dipolar addition
摘要:
The cyclopentadienyl osmium(II) complexes [(eta(5)-C5H5)Os(PPh3)(2)X] [X = Br (1), CH3CN (2)] reacts with sodium azide (NaN3) to yield the corresponding azido complex [(eta(5)-C5H5)Os(PPh3)(2)N-3] (3). This undergoes [3+2] dipolar cycloaddition reaction with activated alkynes like dimethyl and diethyl acetylenedicarboxylate to yield triazolato complexes [(eta(5)-C5H5)Os(PPh3)(2){N3C2(CO2R)(2)}] [R = -CH2CH3 (4) and -CH3 (5)]. The complex 3 also reacts with nitriles such as tetracyanoethylene (TCE), fumaronitrile and p-nitrobenzonitrile to yield complexes of the type [(eta(5)-C5H5)Os(PPh3)(2){N4C2(CN)=C(CN)(2)}] (6), [(eta(5)-C5H5)Os(PPh3)(2){N3C2HCN}] (7) and [(eta(5)-C5H5)Os(PPh3)(2){N4C(C6H4-p-NO2)}] (8). These complexes were fully characterized on the basis of microanalyses, FT-IR and NMR spectroscopic data. The molecular structure of the representative complex [(eta(5)-C5H5)Os(PPh3)(2){N3C2(CO2CH2CH3)(2)}] (4) was determined by single crystal X-ray analysis. (C) 2007 Elsevier B.V. All rights reserved.