Übergangsmetallkomplexe mit schwefelliganden

Abstract

Abstract During a study of the reactions of molybdenum(0) carbonyl complexes with multidentate organosulfur ligands, (NMe 4 ) 2 [Mo(CO) 3 (SC 2 H 4 SC 2 H 4 S)] was obtained from [Mo(CO) 3 (CH 3 CN) 3 ] and (NMe 4 ) 2 (SC 2 H 4 SC 2 H 4 S); subsequent alkylation with 1,2-dibromoethane gave [Mo(CO) 3 TTCN] (TTCN = 1,4,7-trithiacyclonane). TTCN, which up to now had been obtained only with difficulty, is liberated from [Mo(CO) 3 TTCN] by (NMe 4 ) 2 (SC) 2 H 4 SC 2 H 4 S) under regeneration of the starting complex (NMe 4 ) 2 [Mo(CO) 3 (SC 2 H 4 SC 2 H 4 S)]. TTCN and [MoCl 3 (THF) 3 ] yield [MoCl 3 (TTCN)]. [Mo(CO) 4 (norbornadiene)] and (NMe 4 ) 2 (dttd), (dttd 2 = 2,3,8,9-dibenzo-1,4,7,10-tetrathiadecane(−2)), give (NMe 4 ) 2 [μ-dttd{Mo(CO) 4 } 2 ], which reacts to form a Mo(CO) 3 species under heating; further CO substitution is not observed. Treatment of [Mo(CO) 2 (PPh 3 ) 2 (CH 3 CN) 2 ] with C 6 H 4 (SH) 2 and CH 3 SC 6 H 4 SH respectively, leads via redox reactions to the molybdenum(II) complexes [Mo(CO) 2 (PPh 3 ) 2 (C 6 H 4 S 2 )] and [Mo(CO) 2 (PPh 3 )(CH 3 SC 6 H 4 S) 2 ]. Under normal conditions, these complexes show no substitution of PPh 3 by C 6 H 4 S 2 2− or CH 3 SC 6 H 4 S − ; however, under thermally more vigorous conditions in refluxing methoxyethanol, [Mo(CO) 2 (PPh 3 ) 2 (C 6 H 4 S 2 )] and Na 2 (C 6 H 4 S 2 ) yield [Mo IV (C 6 H 4 S 2 ) 3 ] 2− in a redox reaction; the anion is isolated as (NMe 4 ) 2 [Mo(C 6 H 4 S 2 ) 3 ]. [Mo(CO) 3 (CH 3 CN) 3 ] and CH 3 SC 6 H 4 SH yield, at room temperature, the binuclear [Mo 2 (CO) 6 (CH 3 SC 6 H 4 S) 2 ]; with Na/THF, it leads to [Mo(CO) 4 (CH 3 SC 6 H 4 S)] − , with PPh 3 to [Mo(CO) 2 PPh 3 (CH 3 SC 6 H 4 S) 2 ], and with CH 3 SC 6 H 4 S − to [Mo(CO) 4 (CH 3 SC 6 H 4 S)] − as well as to [Mo(CO)(CH 3 SC 6 H 4 S) 3 ] − , which are isolated as NMe 4 + salts. In (NMe 4 )[Mo(CO)(CH 3 SC 6 H 4 S) 3 ], apart from one CO, only sulfur is coordinated to the Mo center; its CO ligand shows an extremely low IR absorption at 1775 cm −1 indicating high electron density at the Mo center. Photochemical substitution of CO by N 2 was not possible either with this CO or with the other CO complexes.