SYNTHESIS, COORDINATION CHEMISTRY AND LIG AND PROPERTIES OF SECONDARYPHOSPHINES R(AR-ASTERISK)PH WITH BULKY AROMATIC SUBSTITUENTS - MOLECULAR-STRUCTURE OF PH(2,4,6-IPR(3)C(6)H(2))PH, (2,4,6-IPR(3)C(6)H(2))(2)PH AND CLAU[PHP(2,4-6-TBU(3)C(6)H(2))H]

The secondary phosphines R(Ar)PH (R = Me, iPr, Ph, Mes, Ar*) (2a-2h) with bulky aromatic substituents Ar (Ar* = 2,3,6-R'3C6H2 R' = iPr, tB u) are obtained in good yields by reaction of RPCl(2), PCl3, PBr3 or A rP(Cl,Br)(2) with 2,4,6-tBu(3)C(6)H(2)Li or 2,4,6-iPr(3)C(6)H(2)MgBr and subsequent reduction of the intermediate halophosphines R(Ar)PX ( X = Cl, Pr) with LiAlH4. The X-ray structural analysis of Ph(2,4,6-iPr (3)C(6)H(2))PH (2g). space group P1, shows P-C-distances of 1.824(1) a nd 1.838(1)Angstrom. The lithium derivatives of 2a-2c are monomeric in solution as indicated by the 1:1:1:1-quartet Li-7-P-31 fine structure of the P-31{H-1} NMR signals at low temperatures. 2a-2c and 2f-2h for m Ni(0) and Fe(0) complexes (CO)(3)NiL (6a-6f) and Fe(CO)(4)L (7a-7d), respectively. The Tolman electronic parameters v of the bulky ligands are almost identical. Within the series 2a-2h the spatial shielding o f the P atoms has been estimated using advanced molecular modeling tec hniques. The bulky ligand 2c forms coinage metal complexes [Cu(CH3CN)( 2)(2c)(2)] [PF6] (8), Cu2Cl2(2c)(2) (9) and Cl-Au(2c) (10). While 10 i s monomeric in solution, in the solid state it forms pairs of head to tail oriented monomers with almost linear Cl-Au-P skeletons (Cl-Au-P 1 75.47(9)degrees) as shown by an X-ray structural analysis.