Oxotechnetium 99mTcO[SN(R)S][S] complexes as potential 5-HT1A receptor imaging agents.

A series of 99mTcO[SN(R)S][S] complexes carrying the 1-(2-methoxyphenyl)piperazine moiety on the tridentate ligand [SN(R)S] was synthesized. For structural characterization and for in vitro binding assays the analogous oxorhenium complexes were prepared. As demonstrated by appropriate competition binding tests in rat hippocampal preparations, all oxorhenium analogues showed affinity for the 5-HT(1A) receptor binding sites with IC(50) values at the nanomolar range (IC(50)= 5.