Reaction of an Osmium(VI) Nitrido Complex with Cyanide: Formation and Reactivity of an Osmium(III) Hydrogen Cyanamide Complex

Reaction of [Os VI (N)( L 1 )(Cl)(OH 2 )] ( 1 ) with CN − under various conditions affords (PPh 4 )[Os VI (N)( L 1 )(CN)(Cl)] ( 2 ), (PPh 4 ) 2 [Os VI (N)( L 2 )(CN) 2 ] ( 3 ), and a novel hydrogen cyanamido complex, (PPh 4 ) 2 [Os III {N(H)CN}( L 3 )(CN) 3 ] ( 4 ). Compound 4 reacts readily with both electrophiles and nucleophiles. Protonation and methylation of 4 produce (PPh 4 )[Os III (NCNH 2 )( L 3 )(CN) 3 ] ( 5 ) and (PPh 4 )[Os III (NCNMe 2 )( L 3 )(CN) 3 ] ( 6 ), respectively. Nucleophilic addition of NH 3 , ethylamine, and diethylamine readily occur at the C atom of the hydrogen cyanamide ligand of 4 to produce osmium guanidine complexes with the general formula [Os III {N(H)C(NH 2 )NR 1 R 2 }( L 3 )(CN) 3 ] − , which have been isolated as PPh 4 salts (R 1 =R 2 =H ( 7 ); R 1 =H, R 2 =CH 2 CH 3 ( 8 ); R 1 =R 2 =CH 2 CH 3 ( 9 )). The molecular structures of 1 – 5 and 7 and 8 have been determined by X‐ray crystallography.