Abstract
Ruthenium-thiolate cyanocarbonyl compounds [Na·2THF][Ru(CO)(CN)(S- C 5 H 4 N) 2 ] (2), and [PPN] [Ru(CO)(CN)(S-C 5 H 4 N) 2 ] (3) were prepared from reactions of [Na][N(SiMe 3 ) 2 ] and cis-[Ru(CO) 2 (S-C 5 H 4 N) 2 ] (1) obtained from reaction of Ru 3 (CO) 12 , Me 3 NO·2H 2 O, and 2-mercaptopyridine in THF. Complexes 1, 2 and 3 were characterized by IR and single-crystal X-ray diffraction. The IR spectrum of complex 2 in the aprotic solvent THF reveals two weak absorption bands for the CN - ligands at 2098 w and 2086 w cm -1 and one strong absorption band 1931 s cm -1 assigned to the carbonyl stretching frequency that support the dimeric architecture with two [Ru(CO)(CN)(S-C 5 H 4 N) 2 ] - units connected through CN-Na + -NC interactions, as observed in the single-crystal X-ray structure. Ethylation of complex 3 by electrophile [Et 3 O][BF 4 ] occurring initially at the more accessible, delicately balanced nucleophilic site to yield the charge-controlled, collision product 4 (Scheme II), and subsequently isomerizing to neutral [Ru(CO)(CNEt)(S-C 5 H 4 N) 2 ] (5) demonstrated the enhanced nucleophilicity toward electrophiles with replacement of carbonyl ligand with cyanide ligand in complex 1, indicative of the strong σ-donor role of the cyanide vs CO ligand. In comparison with displaying a reversible redox process of complex [Fe(CO)(CN)(S-C 4 H 3 N 2 ) 2 ] - , the electrochemistry of complex 3 reveals an irreversible oxidation at 0.29 V (vs Ag/AgNO 3 ).