Transition metal–carbon bonds. Part 54. Complexes of palladium, platinum, rhodium, and iridium with Bu^t₂PCH₂CHMe(CH₂)₃PBu^t₂. Crystal structures of [PdCl(Bu^t₂PCH₂CHMeCHCH₂CH₂PBu^t₂)] and [IrH(Cl)(Bu^t₂PCH₂CHMeCHCH₂CH₂PBu^t₂)]

Abstract

The new diphosphine But2PCH2CHMeCH2CH2CH2PBut2(L) is shown to have 13C n.m.r. shifts which can be calculated empirically from the 13C n.m.r. shifts of related diphosphines. It reacts with [PdCI2(NCPh)2] to give the cyclometallated complex [[graphic omitted]But2)](1c), with the 2-methyl group in a pseudo-equatorial position, as shown by the crystal structure. With [PtCl2(NCBut)2] it gives [Pt2Cl4L2] as a complex mixture of isomeric 16-atom ring chelates, which, on treatment with CF3COOH followed by LiCl, gives [[graphic omitted]But2)]; this was not isolated pure but probably has a structure similar to (1c). Compound L also reacts with [Ir2Cl2(C8H14)4](C8H14= cyclo-octene) to give the cyclometallated hydride complex [[graphic omitted]But2)](2c) with an equatorial methyl group. Some of the isomer with a pseudo-axial methyl group was also formed but it slowly, but completely, isomerises to (2c) in solution. Compound (2c) does not lose dihydrogen to give a carbene on heating, in contrast to [[graphic omitted]But2)]. Compound L reacts with [Rh2Cl2(C8H14)4] to give [[graphic omitted]But2)](2e), but with RhCl3·3H2O it also gives two other species, probably rhodium(I)–olefinic diphosphine complexes. Compound (2e) with sodium propan-2-oxide and CO gives [[graphic omitted]But2)]. Proton, 13C, and 31P n.m.r. and i.r. data are given. Cell dimensions: (1c)a= 1.1907(3), b= 1.6466(4), c= 1.3537(4) nm, and β= 103.99(2)°; (2c)a= 1.1954(4), b= 1.6509(5), c= 1.3665(5) nm, and β= 104.18(3)°.