Rhenium(I) Tricarbonyl Complexes with (2-Hydroxyphenyl)diphenylphosphine as PO Bidentate Ligand

Abstract

In the present work, we investigated potential means to obtain neutral tricarbonyl mixed-ligand fac-[M(CO)LL] complexes (M = Re, Tc) containing the (2-hydroxyphenyl)diphenylphosphine (POH) bidentate ligand (LH) and a series of monodentate ligands (L). First, fac-[Re(CO)(PO)(HO)], 1, was synthesized by reaction of POH and [EtN][Re(CO)Br] in equimolar amounts in MeOH at room temperature. Interestingly, with excess of POH this reaction afforded fac-[Re(CO)(PO)(POH)], 2, with POH operating both as a bidentate and as a monodentate ligand. Owing to the presence of the labile aqua ligand, which can be readily replaced by various monodentate ligands, 1 was further used as a precursor to generate a small library of the desired fac-[M(CO)LL] complexes. Specifically, by reaction of triphenylphosphine (PPh), imidazole (im), pyridine (py), cyclohexyl isocyanide (cisc), and tert-butyl isocyanide (tbi), the following products were readily obtained in excellent yields (92%-95%): fac-[Re(CO)(PO)(PPh)], 3, fac-[Re(CO)(PO)(im)], 4, fac-[Re(CO)(PO)(py)], 5, fac-[Re(CO)(PO)(cisc)], 6, and fac-[Re(CO)(PO)(tbi)], 7. All compounds were fully characterized by elemental analysis, IR and NMR spectroscopies, and electrospray ionization(+) mass spectrometry. Their solid-state structure was elucidated by X-ray crystallography. Of considerable interest is the fact that the corresponding 2'-7' were easily accessible at the Tc-tracer level in quantitative yields after reaction of POH and the respective monodentate ligand L with fac-[Tc(CO)(HO)] in aqueous MeOH, as verified by comparative chromatographic methods adopting dual photo- and radiometric detection modes. The high stability displayed by all Tc complexes during histidine and cysteine challenge assays underscored the suitability of the fac-[M(CO)(PO)L] system for radiopharmaceutical development purposes.

Electrospray ionization study of tricarbonyl fac‐[Re(CO)3(PO)(X)]‐type complexes: influence of ancillary co‐ligands in the release of carbon monoxide

“…The peak at m/z 581 is due to the rearranged ion [Re(CO) 3 (PO)(MeOH) + H] + originating by exchange of water with methanol used as solvent. Cluster ion peaks at m/z 827, 843 and 1095 correspond to the rearranged molecule [Re(CO) 3 (PO)(POH) + H] + (exchange of water for POH generated by partial hydrolysis of complex 1 ; vide infra , complex 6 ), its oxidized adduct ([Re(CO) 3 (PO)(O=POH) + H] + generated by partial decomposition of complex 1 followed by in situ oxidation of POH) and the dimeric species, respectively.…”

“…Rhenium (I) tricarbonyl complexes 1 – 7 were prepared according to published procedures . HPLC‐grade solvents were purchased from Sigma‐Aldrich and used as received.…”

“…In the frame of our ongoing interest in the development of new radiopharmaceutical agents, we have recently synthesized a new family of so called ‘2 + 1’‐type fac ‐[M I (CO) 3 (BID)(MONO)], where M(I) = Re, 99m Tc . The synthetic effort intended to develop a library of novel tricarbonyl complexes amenable to derivatization at the MONO framework to design ‘bifunctional entities’ for theranostic purposes.…”

Crystal structure of fac-aqua[(E)-4-(benzo[d]thiazol-2-yl)-N-(pyridin-2-ylmethylidene)aniline-κ2 N,N′]tricarbonylrhenium(I) hexafluoridophosphate methanol monosolvate

“…, where M is Re or 99m Tc, L 1 is a bidentate ligand (bipyridine, 2-picolinic acid, acetylacetone, etc) and L 2 is a monodentate ligand (aqua, imidazole, phosphine or isocyanide), have been studied extensively for the development of novel radiopharmaceuticals for diagnosis (M = 99m Tc) or radiotherapy (M = 186/188 Re) (Knopf et al, 2017;Mundwiler et al, 2004;Papagiannopoulou et al, 2014;Triantis et al, 2013;Shegani et al, 2017). Furthermore, recent studies have revealed the potential of such fac-[Re(CO) 3 L 1 L 2 ] complexes as anticancer agents (Leonidova & Gasser, 2014).…”

Μελέτη Συμπλόκων Ρηνίου Ως Νέων Αντικαρκινικών Παραγόντων

“…Τα κύρια ισότοπα του ρηνίου και των γειτονικών του στοιχείων καθώς και κάποιες ιδιότητες τους φαίνονται στην Εικόνα 1.1. 9 Τα ισότοπα 186 Re (εκπομπή β -, t1/2 = 90 ώρες, Εmax = 1.07 MeV, εμβέλεια ιστού 5 mm) και 188 Re (εκπομπή β -, t1/2 = 17 ώρες, Εmax = 2.1 MeV, εμβέλεια ιστού 11 mm) έχουν φυσικές ιδιότητες (Πίνακας 1.1) που τα κάνουν πολύ ελκυστικά για τη ραδιοθεραπεία του καρκίνου. 10,11 Ιδιαίτερη έμφαση έχει δοθεί στο 188 Re το οποίο μπορεί να παραληφθεί από γεννήτρια βολφραμίου -188 (t1/2 = 69 μέρες) (Σχήμα 1.1).…”