Oxorhenium(V) complexes containing tridentate Schiff-base and monothiol coligands

Abstract

The reaction of [n-(C(4)H(9))(4)N][ReOBr(4)(OPPh(3))] with the tridentate Schiff-base [HOC(6)H(4)C(H)NC(6)H(4)SH] allows for the isolation of [ReOBr{eta(3)-(OC(6)H(4)C(H)NC(6)H(4)S)}] (1). The reaction of [n-(C(4)H(9))(4)N][ReOBr(4)(OPPh(3))] with [HOC(6)H(4)C(H)NC(6)H(4)SH] and the appropriate benzenethiol (C(6)H(4)X-4-SH) where X=H, Br, Cl, F, and OCH(3) in methanol-acetonitrile treated with triethylamine has led to the isolation of a series of rhenium complexes of the type [ReO{eta(3)-(OC(6)H(4)C(H)NC(6)H(4)S)} (eta(1)-C(6)H(4)X-4-S)] (X=H (2), Br (3), Cl (4), F (5), and OCH(3) (6)). Likewise, under similar reaction conditions, the use of benzylmercaptan ligands of the type (C(6)H(4)X-4-CH(2)SH) where X=H, Cl, F, and OCH(3) has led to the isolation of a series of rhenium complexes of the type [ReO{eta(3)-(OC(6)H(4)C(H)NC(6)H(4)S)} (eta(1)-C(6)H(4)X-4-CH(2)S)] (X=H (7), Cl (8), F (9), and OCH(3) (10)). The incorporation of the appropriate amine functionality into the substituent R of the monodentate ligand allows for the isolation of a cationic oxorhenium(V) species, namely, [ReO{eta(3)-(OC(6)H(4)C(H)NC(6)H(4)S)} (eta(1)-C(5)H(4)NH-2-S)][Br] (11).

Exploring oxorhenium ‘3+1’ mixed-ligand complexes carrying the S-benzyl-3-[(2-hydroxyphenyl)methylene]dithiocarbazate [ONS]/monothiol [S] donor set: synthesis and characterization

“…The measurement uses the two largest angles contained in the mean basal plane, which expressed in the form (β−α)/ 60 give a unitless value ranging from 0 to 1 with τ=0 for perfect square pyramid, and τ=1 for ideal triagonal bipyramid. The τ value of 0.31 for 4 is higher than those reported previously in this laboratory in the investigation of [ONS]/[S] '3+1' complexes [11,12] …”

“…However, the stability of these '3+1' complexes is strongly dependent on small structural variations of the tridentate/monothiol ligand sets, especially of the tridentate ligands. [11] and 6-thiomethyl-2-pyridinemethanol [12]. The ReO 3+ core complexes of these ligands are characterized by an almost ideal square pyramidal configuration of the ReO 3+ core.…”

Synthesis and structural characterization of rhenium(I) tricarbonyl complexes with the bidentate ligands o-(diphenylphosphino)benzaldehyde (P∩O) and o-[(diphenylphosphino)benzylidene]analine (P∩N)

“…The inevitable formation of multiple isomers differing in their pharmacokinetics [10] aroused interest in developing an alternative '3+1' approach, in which a neutral oxometal complex in a distorted square pyramidal or trigonal bipyramidal molecular geometry was prepared by employing the mixed tridentate (SNS, ONS, ONO or SSS) ligand and mondentate thiol ligand with the appropriate MO 3+ precursors [11][12][13][14]. These '3+1' integrated complexes eliminated the possibility of syn and anti stereoisomers that are often produced in the tetradentate complexes, but they were found to be relatively unstable in vitro and in vivo due to metabolism and replacement of the monothiol ligand through transchelation by physiological thiols such as cysteine and glutathione [15].…”

Syntheses and structural characterization of rhenium-bis-hydrazinopyrimidine core complexes with thiolate and Schiff base coligands

“…While the chemistry of 2-hydrazinopyrimidine is often analogous to that of 2-hydrazinopyridine, it does offer some advantages in terms of solubility and derivatization. In an effort to develop the comparative chemistries of 2-hydrazinopyridine and 2-hydrazinopyrimidine with rhenium, the starting material [ReCl 3 (η 1 NNC 4 H 3 N 2 H)(η 2 -HNNC 4 H 3 N 2 )] (1) was prepared and reacted with mercaptopyrimidine and Schiff base compounds, both of which had previously been demonstrated to act as useful coligands for the purification and stabilization of the radiopharmaceutical preparations [11,13]. The syntheses and structures of the rhenium-bispyrimidinodiazine core complexes [Re(η 1 -C 4 Mo (mol.…”