Synthesis, structure and reactivity of bromo- and aquatricarbonylrhenium(I) phosphinite and phosphonite derivatives

[ReBr(CO)(5)] reacted with phosphinite or phosphonite ligands in benzene or toluene to yield fac-(1) or titer, trans-(2) complexes, ([ReBr(CO)(3)(L)(2 )] L = PPh2(OMe), a; PPh2(OEt), b; PPh(OMe)(2), c; PPh(OEt)(2), d) characte rized by elemental analysis, mass spectrometry, IR and NMR (H-1, C-13 and P -31) spectroscopies, and for complexes 1b, 2c and 2d, X-ray diffractometry was used. Complexes 2a-2d reacted with Ag[BF4] in wet acetone to form moder ate yield of mer, trans-[Re(H2O)(CO)(3)(L)(2)][BF4] (3). Comparison of the spectra of compounds 3 with those of precursors 2 together with the diffrac tometric results for compounds 3a-3c, show that all the complexes have the same configuration around the rhenium atom. Crystals of compounds 3 consist of centrosymmetric dimers formed by hydrogen bonds between the water molec ules and the BF4- anions. The lability of compounds 3 was explored by F-19 and P-31 NMR, and in the case of 3c the complex [Re(eta (1)-BF4)(CO)(3){PPh (OMe)(2)}(2)] (4c) was isolated from the mother liquor. Spectroscopic and d iffractometric studies of 4c show monodentate coordination of the tetrafluo rborato ligand to the rhenium atom. (C) 2001 Elsevier Science Ltd. All righ ts reserved.