Abstract: Haloaryl compounds are lithiated and thereafter metalated with one of the following organometallic groups: Sn(n--Bu).sub.3 or SnMe.sub.3. The resulting aryltin compound can be transmetalated in site-specific reaction with one of the following organometallic groups: HgX, Hg(OAc).sub.2, BX.sub.3, or BZ.sub.2, wherein X is Cl, Br, or I, and Z is alkyl or alkoxy. The metalated compounds are subsequently radiohalogenated via a demetalation reaction. A functional group suitable for conjugation to protein can be added subsequent or preferably prior to the radiohalogenation.Also compounds of the formula: R.sub.1 --Ar--R.sub.2, wherein R.sub.1 is either a radiohalogen or any one of the organometallic groups stated above, Ar is aromatic or heteroaromatic ring, and R.sub.2 is a short-chain substituent that does not activate the aromatic ring and that bears a functional group, or a precursor thereof, suitable for conjugation to protein under conditions that preserve the biological activity of the protein.

Abstract: Highly iodinated borane and carborane cage molecules, having from 60% to 90% w/w iodine, are disclosed as new and useful X-ray contrast media when combined with a pharmaceutically acceptable carrier. The inclusion of appropriate functional group substituents, such as hydrophilic moieties, increases solubility and lowers toxicity.