Rhenium and technetium complexes with diphenyl(2-pyridyl)phosphine

The potentially bidentate ligand diphenyl(2-pyridyl)phosphine (PPh(2)py) reacted with (NEt4)(2)[(MX3)-X-L(CO)(3)] complexes (M=Re, Tc; X=Cl, Br) to give (NEt4)[(MX2)-X-I(CO)(3)(PPh(2)py-P)] or [(MX)-X-I(CO)(3)(PPh(2)py-P)(2)] depending on the amount of the ligand used. The reaction with (NBu4)[(TcNCl4)-N-VI] yielded [(TcNCl2)-N-V(PPh(2)py-P)(2)] whereas from the reaction with (NBu4)[ReOCl4] the complexes [Re(V)oCl(3)(PPh(2)py-P,N)], [(ReOCl3)-O-V(OPPh(2)py-O,N)], [(ReCl4)-Cl-IV(OPPh(2)py-O,N)] and [(ReCl3)-Cl-IV(OH)(OPPh(2)py-O,N)] have been isolated. Reduction of the metal center occurs using an excess of PPh(2)py and heating of the reaction mixtures under reflux. The products have been characterised spectroscopically and by X-ray structure analysis. Monodentate co-ordination via phosphorus has been found for the rhenium(I) carbonyl complexes and [(TcNCl2)-N-V(PPh(2)py-P)(2)]. In the latter compound a trigonal-bipyramidal coordination sphere is formed with the phosphines as axial ligands (bond angle P-Tc-P: 161.69(3)degrees). The chelated complexes show small N-Re-P and N-Re-O bile angles of 63.6 degrees and 77.7-82.2 degrees due to the four-membered or five-membered chelate rings. The pyridine nitrogen occupies the axial position (trans to "O2-") in [ReOCl3(PPh(2)py-P,N)] whereas equatorial co-ordination is found in [ReOCl3(OPPh(2)py-O,N)]. (C) 1999 Elsevier Science Ltd. All rights reserved.