R1NHCSeNR2R3

R1NHCSeNR2R3 is a generic notation used to describe a family of organoselenium compounds known as selenoureas, in which a carbon atom bears a double bond to selenium and single bonds to two nitrogen-bearing substituents. The formal structure is R1NH-C(=Se)-NR2R3, where R1, R2 and R3 denote organic groups such as alkyl or aryl substituents. The compound class can be viewed as the selenium analogue of carbamoyl derivatives, with resonance placing electron density on N and Se.

Structure and properties: The central C(=Se) unit imparts polarity to the molecule; the N–H bond on the N1 substituent can engage in hydrogen bonding. The geometry around carbon is typically near-trigonal planar. Substitution pattern with R1, R2, R3 influences solubility, stability, and reactivity; some derivatives crystallize, others are oils. The C=Se bond distinguishes these from corresponding carbamoyl derivatives and affects their coordinating behavior and reactivity.

Synthesis: Selenoureas are commonly prepared by reaction of primary amines with electrophilic selenium sources such as isoselenocyanates or selenocarbonyl chlorides, often under basic conditions to promote amide-like formation. Alternative routes include transformation of preformed ureas with selenium reagents or oxidation of corresponding sulfur analogues.

Reactions and applications: As organoselenium donors, selenoureas can participate in selenium transfer or be converted to selenocyanates and related selenium-containing motifs. They serve as ligands for metal complexes and as intermediates in the preparation of selenium-containing heterocycles. In some cases, derivatives have been explored for biological activity and as building blocks in organic synthesis.

Safety and handling: Selenium-containing compounds can be toxic; appropriate handling, ventilation, and waste disposal procedures are required.