Nitrogen, phosphorus, arsenic, antimony and bismuth

Abstract

This chapter reviews the literature reported during 2005 on the chemistry of nitrogen, phosphorus, arsenic, antimony and bismuth. PreambleOnce again the study of the chemistry of the pnictogens has provided considerable challenges to both synthetic and theoretical chemists. Significant new advances and insights into have been made, of particular note are the developments in the areas of activation of dinitrogen, such as the work of Schrock on molybdenum complexes 1,2 and the discovery of an amido-hydride complex from activation of ammonia. 3 Further highlights include the continued expansion of the use of metal phosphinidene complexes as synthetic reagents for the production of novel phosphoruscontaining materials and the synthesis of several new cationic arsenic-containing species.As in previous years and due to space restrictions this review will not, in general, consider the use of the trivalent elements as ligands, however reviews on ''user friendly'' primary phosphines 4 and how to evaluate the net donor abilities of phosphines 5 have appeared. NitrogenThe activation of dinitrogen remains a major area of interest. The molybdenumcentred reduction of dinitrogen to ammonia remains one of the most impressive methods of nitrogen fixation and a review on this subject has appeared 1 as has a comprehensive study into several aspects of this chemistry. 2 It has been shown that under an atmosphere of N 2 , the dimer [Ta(Z 5 -C 5 Me 4 R)] 2 (m-Cl) 4 (R = Me, Et) disproportionates to give [Ta(Z 5 -C 5 Me 4 R)] 2 (m-Z 1 ,Z 1 -N 2 ) as the nitrogen-containing product. 6 The dinitrogen may be considered to have undergone a four-electron reduction with the tantalum now existing in the (V) oxidation state. In a similar fashion, reduction of [Ti(Z 5 -C 5 Me 5 )Cl 3 ] in the presence of substituted fulvene gives rise to dinuclear species containing a (m-Z 1 , Z 1 -N 2 ) ligand. 7 The reduction of the zirconium complex [NPN]ZrCl 2 (thf) [NPN = PhP(CH 2 SiMe 2 NPh) 2 ] under nitrogen results in the formation of [NPN]Zr(m-Z 2 , Z 2 -N 2 )(thf). 8 A similar reaction with the titanium analogue results in the insertion of dinitrogen into the Ti-PPh bond and formation of 1. Using a related ligand set within the coordination sphere of tantalum, Fryzuk has also shown that it is possible to convert hydrazine to bridging Ta-NH-Ta groups. 9 A reaction of the same precursor with Me 2 NNH 2 results in the formation of a complex containing a bridging nitride ligand. The oxidative addition