The First Example of Coordination of a Tricyclic Hydrophosphorane to Platinum(II). X-ray Crystal Structure of an Unusual Platinated Phosphorane

The reaction of (4S,9S)-4,9-diethyl-2,11-dioxa-5,8-diaza-1λ5-phosphatricyclo[6.3.0.01.5]undecane (1) with [Pt(COD)Cl2] (COD = cycloocta-1,5-diene) at 0 °C gave [(1,2:5,6-η)-1,5-cyclooctadiene][(4S,9S)-4,9-diethyl-5H-5,8-diaza-2,11-dioxa-1λ5-phosphatricyclo[6.3.0.01.5]undecyl-1]chloroplatinum chloride (2). If the reaction was performed in the presence of AgBF4, the corresponding BF4- salt (4) was isolated. Complex 2 was converted to cis-dichloro{(4S,9S)-4,9-diethyl-2,11-dioxa-5,8-diaza-1-phosphabicyclo[6.3.0]undecane-P,N}platinum (3). Variable-temperature 31P NMR studies of complexes 2 and 4 have been carried out in the range from −93 to 50 °C. The structure of compound 4 has been determined by X-ray crystallography. Complex 4 has a slightly distorted trigonal-bipyramidal geometry around the phosphorus, with the platinum fragment in the equatorial position. The P−Nax bond distance is 2.002(5) A. The Pt atom exhibits a nearly square-planar coordination geometry.