Terminal Sulfido, Selenido, and Tellurido Complexes of Tungsten

Article abstract of DOI:10.1021/ic00129a021

The terminal chalcogenido complexes trans-W(PMe3)4(E)2 (E = S, Se, Te) have been synthesized by the reactions of W(PMe3)4(η2-CH2PMe2)H withH2E (E = S, Se) and elemental Te. W(PMe3)4(Te)2 is the first example ofa transition-metal complex containing a terminal tellurido ligand. Eachof the chalcogenido complexes W(PMe3)4(E)2 reacts reversibly with RCHO to yield the η2-aldehyde derivatives W(PMe3)2(E)2(η2-OCHR), although the equilibrium constants vary strongly as a function of the chalcogen, with KS >> KSe > KTe. The PMe3 ligands of W(PMe3)4(S)2 and W(PMe3)4(Se)2 are readily displaced by Bu(t)NC to give W(PMe3)2(CNBu(t))2(E)2. In marked contrast, however, the corresponding reaction of the tellurido derivative W(PMe3)4(Te)2 with Bu(t)NC results in the unprecedented coupling of the two terminal tellurido ligands, leading to the formation of the η2-ditellurido derivative W(PMe3)(CNBu(t))4(η2-Te2). Structural and bonding aspects of the terminal chalcogenido complexes have been probed by X-ray diffraction, while (77)Se and (125)Te NMR spectroscopieshave identified a linear correlation between (77)Se and (125)Te NMR chemical shifts for structurally analogous selenido and tellurido complexes. W(PMe3)4(S)2 is monoclinic, P2/n (No. 13), a = 15.914(2) ?, b = 9.682(2) ?, c = 15.926(3) ?, β = 111.92(2)°, Z = 4. W(PMe3)4(Se)2 is monoclinic, P2/n (No. 13), a = 16.040(5) ?, b = 9.738(2) ?, c = 16.096(3) ?, β = 113.27(2)°, Z = 4. W(PMe3)4(Te)2 is tetragonal, I4-2m (No. 121), a = b = 9.717(1) ?, c = 12.360(2) ?, Z = 2. W(PMe3)4(Se)H2 is monoclinic, Cc (No. 9), a = 9.580(2) ?, b = 15.757(3) ?, c = 14.860(3) ?, β = 98.54(2)°, Z = 4. W(PMe3)2(CNBu(t))2(S)2 is monoclinic, P21/n (No. 14), a =11.003(2) ?, b = 10.513(3) ?, c = 11.947(3) ?, β = 109.87(2)°, Z = 2. W(PMe3)2(CNBu(t))2(Se)2 is monoclinic, P21/n (No.14), a = 11.147(5) ?, b = 10.617(5) ?, c = 11.973(4) ?, β = 110.16(3)°, Z = 2. W(PMe3)2(Te)2(η2-OCH2) is orthorhombic, Pnma (No. 62), a = 10.441(3) ?, b = 11.299(4) ?, c = 13.812(4) ?, Z = 4. W(PMe3)2(S)2(η2-OCHPh) is monoclinic, P21/c (No. 14), a = 12.561(3) ?, b = 8.684(1) ?, c = 18.182(3) ?, β = 108.57(2)°, Z = 4. W(PMe3)2(Se)2(η2-OCHPh) is monoclinic, P21/c (No. 14), a = 12.563(5) ?, b = 8.731(4) ?, c = 18.461(6) ?, β = 109.22(3)°, Z = 4. W(PMe3)2(Te)2(η2-OCHPh) is monoclinic, P21/n (No. 14), a = 12.661(2) ?, b = 8.931(1) ?, c = 18.779(4) ?, β = 108.47(2)°, Z = 4. W(PMe3)(CNBu(t))4(η2-Te2) is orthorhombic, Pbca (No. 61), a = 18.097(4) ?, b = ...