Transition Metal Complexes of Positively Charged Crown Thioethers

Treatment of trans-M(CO)_2(syn-Me_8[16]aneS_4)(M=Mo，W)with excess MeOTf gave the tertiary sulfonium ion complex trans-{M(CO)_2(syn-Me_9[16]aneS_4)}OTf(1a，M=Mo；=1b，M=W)，while the similar reaction with HOTf(1eq.)Afforded the secondary sulfonium complex trans-M(CO)(OTf)(syrMe_8H[16]aneS_4)(2a，M=Mo；2b，M=W)。The facile evolution of CO observed on protonation and the X-ray structural study of 1a indicate that Ppi-acceptor ability increases in the order，R_2SH^+&gt；R_2 MeS^+&gt；R_2S.Oxidative addition of HOTf to2took place stepwisely to give 7-and 8-coordinate hydrido complexes trans-{WH(CO)(OTf)(syn-Me_8H[16]aneS_4)}OTf(3)and trans-{MH_2(CO)(OTf)(syn-Me_8H[16]aneS_4)}(OTf)_2(4a，M=Mo；4b，M=W)，respectively.The X-ray structural study of 4b indicate that the W atom assumes distorted bicapped Oh with a novel W···H-S^+interaction(W···H1.92*)。A similar protonation of1 with HOTf produced trans-{MH(CO)(syn-Me_9[16]aneS_4)}OTf(5a，M=Mo；5b，M=W)。In5a the hydrido ligand interacts strongly with the teriary sulfonium S atom to form Mo-H-S^+3c-2e bond(Mo-H1.48，H-S^+1.32*)。The methylation of fac-M(CO)_3(syn-Me_8[16]aneS_4)(M=Mo，W)with an excess of MeOTf give fac{M(CO)_3(syn-Me_9[16]aneS_4)}OTf(6a，M=Mo；6b，M=W)，where the teriary sulfonium ion is uncoordinated。In sharp contrast to the facile protonation of the thiamacrocycle in M(0)complexes，the Mo(IV)complexes trans-Mo(S)_2(syn-Me_8[16]aneS_4)and trans-Mo(N)(N_3)(syn-Me_8[16]aneS_4)failed to give the corresponding secondary sulfonium ion complexes.Instead，they produced a novel dinuclear trisulfide{Mo_2(mu-S)(S)_2(syn-Me_8[16]aneS_4)_2}(BF_4)_2(7)containing a linear S=Mo-S-Mo=S linkage and parent imido complex trans-{Mo(NH)(OTf)(syn-Me_8[16]aneS_4)}OTf(8)，respectively.

Treatment of trans-M (CO) _2 (syn-Me_8 [16] aneS_4) (M=Mo, W) with excess MeOTf gave the tertiary sulfonium ion complex trans- {M (CO) _2 (syn-Me_9 [16] aneS_4)} OTf (1a, M=Mo ; =1b, M=W), while the similar reaction with HOTf (1 eq.) afforded the secondary sulfonium complex trans-M (CO) (OTf) (syrMe_8H [16] aneS_4) (2a, M=Mo ; 2b, M=W). The facile evolution of CO observed on protonation and the X-ray structural study of 1a indicate that Ppi-acceptor ability increases in the order, R_2SH^+>R_2MeS^+>R_2S.Oxidative addition of HOTf to 2 took place stepwisely to give 7-and 8-coordinate hydrido complexes trans-{WH (CO) (OTf) (syn-Me_8H [16] aneS_4)} OTf (3) and trans- {MH_2 (CO) (OTf) (syn-Me_8H [16] aneS_4)} (OTf) _2 (4a, M=Mo ; 4b, M=W), respectively. The X-ray structural study of 4b indicate that the W atom assumes distorted bicapped Oh with a novel W・・・H-S^+interaction (W・・・H1.92*). A similar protonation of 1 with HOTf produced trans- {MH (CO) (syn-Me_9 [16] aneS_4)} OTf (5a, M=Mo ; 5b, M=W). In 5a the hydrido ligand interacts strongly with the teriary sulfonium S atom to form Mo-H-S^+3c-2e bond(Mo-H1.48, H-S^+1.32*). The methylation of fac-M (CO) _3 (syn-Me_8 [16] aneS_4) (M=Mo, W) with an excess of MeOTf give fac {M (CO) _3 (syn-Me_9 [16] aneS_4)} OTf (6a, M=Mo ; 6b, M=W), where the teriary sulfonium ion is uncoordinated. In sharp contrast to the facile protonation of the thiamacrocycle in M (0) complexes, the Mo (IV) complexes trans-Mo (S) _2 (syn-Me_8 [16] aneS_4) and trans-Mo (N) (N_3) (syn-Me_8 [16] aneS_4) failed to give the corresponding secondary sulfonium ion complexes. Instead, they produced a novel dinuclear trisulfide {Mo_2 (mu-S) (S) _2 (syn-Me_8 [16] aneS_4) _2} (BF_4) _2 (7) containing a linear S=Mo-S-Mo=S linkage and parent imido complex trans- {Mo (NH) (OTf) (syn-Me_8[16]aneS_4)} OTf (8), respectively.