The synthesis, characterization and X-ray crystal structure of the rhenium organodiazenido, organodiazene complex [ReCl 2(PPh 3) (NNC 5H 4N) (HNNC 5H 4N)

Abstract

The reaction of the Re(III) complex [ReCl 3(NNC 5H 4NH) (HNNC 5H 4N)] ( 1) with triphenylphosphine and a proton scavenger in methanol gives the neutral complex [ReCl 2(PPh 3) (NNC 5H 4N) (HNNC 5H 4N)] ( 2). The neutral, six-coordinate complex contains a singly-bent pyridyldiazenido ligand and a bidentate, organodiazene ligand that is chelated through the pyridine nitrogen atom. The IR spectrum displays a series of strong absorptions in the 1600-1150 cm −1 region characteristic of the organohydrazide ligands. The FAB(+) mass spectrum displays the protonated parent ion of 733 m/z and the ion [ReCl(PPh 3) (NNHC 5H 4N) (HNNC 5H 4N)] + of 697 m/z. The X-ray crystal structure of this complex displays a cis arrangement of chloride ligands with the pyridine nitrogen atom of the organodiazene chelate located in the position trans to the pyridyldiazenido ligand. Crystal data for ReCl 2PN 6C 28H 26: monoclinic space group P2 I/ n, a = 10.263(2), b = 14.938(3), c = 19.650(4) A ̊ , β = 97.54(3)° with Z = 4 to give V = 2995.5(15) A ̊ 3 . The coordination geometry is distorted octahedral. The ReN bond length to the pyridine nitrogen atom of the organodiazene chelate is 2.147(15) Å, while the ReN bond to the diazene-α-nitrogen atom is 1.915(21) Å. The NN bond length of this ligand is 1.340(26) Å, indicative of multiple bonding within the chelated ligand. The ReN bond length of the pyridyldiazenido ligand is 1.778(14) Å, and the NN bond length is 1.212(22) Å, again reflecting the multiple bonding throughout the singly-bent, organodiazenido unit. The bond angle of the ReNN linkage is 172.8(13)°.