LEWIS BASICITY AND LIGAND BEHAVIOR OF CYCLOPROPYLPHOSPHINES

The preparation and properties of tricyclopropylphosphine and cyclopropyldiphenylphosphine are described. Tricyclopropylphosphine is a stronger Lewis base than (i-C3H7)3P toward the Lewis acids B(CH3)3, BF3, and BH3. Tricyclopropylphosphine will react with cyclopropyl bromide to yield (c-C3H5)4P+Br-, which appears to be stable only in the solid state. The P-S and P-Se stretching frequencies of (c-C3H5)3PS, (c-C3H5)3PSe, and (i-C3H7)3PS are all higher than the values reported previously15 for tri(n-alkyl)- and tri(aryl)phosphine chalco-genides. The mono- and disubstituted tungsten carbonyl complexes of (c-C3H15)3P and (c-C3H5)(C6H5)2P have been prepared and the 31P nmr chemical shifts of the free and complexed phosphines determined. The coordination chemical shifts of both phosphines are anomalously small. The 183W-31P coupling constants and E species CO stretching frequencies of the (phosphine)W(CO)5 compounds fit the linear relationship of Grim, et al., and suggest that the cyclopropylphosphines behave as π-acceptor ligands. Attempts to prepare an anion radical from (c-C3H5)3P or (c-C3H6)3PO were unsuccessful. © 1969, American Chemical Society. All rights reserved.