On the nuclearity of tricarbonylrhenium(I) complexes with N,O,O-donating Schiff bases derived from amino acids

The reaction of [ReBr(CO)5] with AgOOCCH3 followed with N-(2-hydroxynaphtalidene)-β-alanine (bala2hnH2); NEt4[ReBr3(CO)3] with the potassium salt of N-(2-hydroxynaphtalidene)-(d,l)-β-phenylalanine (bphala2hnH2), or with N-(5-bromine-2-hydroxysalicylidene)-(d,l)-β-phenylalanine (bphalabrsalH2) gave the complexes [fac-{Re(bala2hnH)(CO)3}2] (1), (H3O)[Re(fac-bphala2hn)(CO)3]·CHCl3·H2O (2), K[fac-Re(bphala2hn)(CO)3]·⅓CHCl3·2H2O (3) and K[fac-Re(bphalabrsal)(CO)3]·2H2O (4), respectively. Single crystal X-ray crystallography showed that the neutral dinuclear complex 1 is centrosymmetric with each rhenium(I) atom having an octahedral coordination geometry comprising of three terminal carbonyl ligands, in a fac configuration, and both ligands bala2hnH are bridging and chelating the two rhenium(I) centers. In the anionic mononuclear complexes 2 and 3, bphala2hn2– acts as a N,O,O tridentate ligand to the fac-{Re(CO)3}+ fragment giving rise an octahedral geometry around the rhenium(I) atom.