Journey from Mo-Mo quadruple bonds to quintuple bonds.
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 degrees C gives two paddlewheel type quadruply bonded dimolybdenum complexes, Mo(2)(mu-Cl)[Cl(2)Li(OEt(2))][mu-eta(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) A, 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)[mu-eta(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) A (3) and 2.0157(4) A (4), a consequence of the formation of the second delta 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.
Tsai
Yi-Chou
YC
Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC. yictsai@mx.nthu.edu.tw
Chen
Hong-Zhang
HZ
Chang
Chie-Chieh
CC
Yu
Jen-Shiang K
JS
Lee
Gene-Hsiang
GH
Wang
Yu
Y
Kuo
Ting-Shen
TS
D018360:Crystallography, X-Ray; D008982:Molybdenum / Q000737:chemistry*; D013696:Temperature
D008982:Molybdenum