摘要
(Chemical Equation Presented) Heating K 4 Mo 2 Cl 8 and 2 equiv of Li[RC(NDipp) 2 ] (R = H, Ph; Dipp = 2,6-i-Pr 2 C 6 H 3 ) in tetrahydrofuran (THF) at 60°C gives two paddlewheel type quadruply bonded dimolybdenum complexes, Mo 2 (μ -Cl)[Cl 2 Li(OEt 2 )][μ- η 2 -RC(N-2,6-i-Pr 2 C 6 H 3 ) 2 ] 2 (R = H (1), Ph (2)). The Mo-Mo bond lengths of 1 and 2 are 2.0875(4) and 2.0756(8) Å, respectively, indicating typical Mo-Mo quadruple bonds. Reduction of 1 and 2 by two electrons results in the isolation of their corresponding Mo-Mo quintuple bonded complexes, Mo 2 [μ- η 2 -RC(N-2,6-i-Pr 2 C 6 H 3 ) 2 ] 2 (R = H (3), Ph (4)), and the Mo-Mo bond lengths dramatically decrease to 2.0187(9) Å (3) and 2.0157(4) Å (4), a consequence of the formation of the second δ bond and representing the shortest metal-metal bonds beyond the first row elements. The Mo-Mo quintuple bonding characters are corroborated by DFT calculations at the level of BP86/def2-TZVP and BP86/def2-TZVPP. © 2009 American Chemical Society.