trans-bis(triphenylphosphine)phthalocyaninato(2-)rhenium(II): synthesis, properties, and crystal structure

Dirheniumheptoxide reacts with phthalodinitrile in boiling 1-chloronaphthalene and subsequent reprecipitation of the green raw product from conc. sulfuric acid to yield an oxo-phthalocyaninate of rhenium, which is reduced by molten triphenylphosphine forming dark green trans-bis(triphenylphosphine)phthalocyaninato(2-)rhenium(II), trans[Re(PPh3)2pc2-]. The latter crystallizes triclinic in the space group P anti 1 with the cell parameters as follows: a = 11.512(2) A, b 12.795(2) A, c = 12.858(2) A, α = 64.42(2) , β = 79.45(2) , γ 72.74(1) ; V = 1628.1(5); Z = 1. Re is in the centre of the (Np)4 plane (Np: N1, N3) and coordinates two triphenylphosphine ligands axially in trans position. The average Re-Np and Re-P distances are 2.007(1) and 2.516(3) A, respectively. Despite the many extra bands the typical B, Q and N regions of the pc2- ligand are observed at ca. 16500, 28900/32900 and 35300 cm-1. A weak band group at ca. 8900 cm-1 is attributed to a trip-multiplet transition, another one at ca. 14500 cm-1 to a P → Re charge transfer. The vibrational spectra are dominated by internal vibrations of the pc2- ligand. The very weak intensity of the IR bands at 905 and 1327 cm-1 are diagnostic of the presence of ReII. (orig.)