Carboranes as ligands for the preparation of organometallic Tc and Re Radiopharmaceuticals. Synthesis of [M(CO)(3)(eta-2,3-C(2)B(9)H(11))](-) and rac-[M(CO)(3)(eta-2-R-2,3-C(2)B(9)H(10))](-) (M = Re, (99)Tc; R = CH(2)CH(2)CO(2)H) from [M(CO)(3)Br(3)](2-).
A new and high yielding method for the synthesis of [M(CO)(3)(eta(5)-2,3-C(2)B(9)H(11))](-) and the bifunctional metal complexes, rac-[M(CO)(3)(eta(5)-2-R-2,3-C(2)B(9)H(10))](-) (R = CH(2)CH(2)CO(2)H), from [M(CO)(3)Br(3)](2)(-) (M = Re, (99)Tc) was developed. The general approach entailed the addition of nido-[(C(2)B(9)H(12))(-)], or the acid substituted analogue, to [M(CO)(3)Br(3)](2)(-) (M = Re, (99)Tc) in the presence of TlOEt in THF. It was also possible to prepare the reported products in water using sodium carbonate in place of TlOEt. The reported approach led to the preparation, and X-ray crystallographic structure determination, of the first Tc-carborane complex reported to date (a = 13.606(17) A, b = 10.685(13) A, c = 15.534(16) A, alpha = gamma = 90 degrees, beta = 111.84(2) degrees). Because of the stabilities of the metal complexes, and the fact that the compounds can be prepared in water, the bifunctional derivatives can be considered as novel synthons for the preparation of organometallic (99m)Tc and (186/188)Re radiopharmaceuticals.
Valliant
John F
JF
Department of Chemistry, McMaster University, Hamilton, Ontario, Canada L8S 4M1. valliant@mcmaster.ca
Morel
Pierre
P
Schaffer
Paul
P
Kaldis
John H
JH
D001896:Boron Compounds / Q000737:chemistry*; D002625:Chemistry, Organic / Q000379:methods; D002851:Chromatography, High Pressure Liquid; D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D015609:Organotechnetium Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D019275:Radiopharmaceuticals / Q000138:chemical synthesis* / Q000737:chemistry; D012211:Rhenium / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
D001896:Boron Compounds; D009942:Organometallic Compounds; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D012211:Rhenium