Abstract
Treatment of a mixture of MoCl3(THF)3 and zinc powder with the lithiated amidinate Li[μ-η2-HC(N-2,6-Et2C6H3)2] gave the trinuclear molybdenum complex Mo2(μ-Cl)[Cl2MoLi(μ-Cl2)(thf)(OEt2)][μ-η2- HC(N-2,6-Et2C6H3)2]2 (1), where the central core is a quadruply- bonded Mo2 unit. Subsequent reduction of complex 1 with 2 equiv KC8 eliminated the pendant molybdenum atom and led to the isolation of a quardruply-bonded complex Mo2(μ-Cl)[Cl2(μ-Li(thf)2)][μ-η2-HC(N-2,6- Et2C6H3)2]2 (2), displaying a paddlewheel structure, where the Mo-Mo quadruple bond length is 2.0817(10)Å. The structure of 2 is similar to the reported complexes by us Mo2(μ-Cl)[Cl2(μ-Li(thf)2)][μ-η2-RC(N-2,6-i- Pr2C6H3)2]2(R = H, Ph). Upon reduction of complex 2 with KC8, a novel quintuply-bonded complex Mo2(μ-Li)[μ-η2-HC(N-2,6-Et2C6H3)2]3 (3) was obtained. It is interesting to note that 3 displays a paddlewheel structure with a lithium ion coordinated to two quintuply-bonded Mo centers. The Mo-Mo bond length was determined to be 2.0612(4)Å by single crystal X-ray diffraction. In addition, the reaction of a mixture of MoCl3(THF)3 and KC8 with different concentration of the lithiated amidinate engendered the formation of the quardruply-bonded complex Mo2(μ- Cl)[μ-η2-HC(N-2,6-Et2C6H3)2]3(4). However, reaction of a mixture of MoCl3(THF)3 and KC8¬ with the lithiated triazenide resulted in the formation of the quardruply-bonded dimolybdenum complex Mo2(μ- Cl)[Cl2Li(thf)2][μ-η2-N(N-2,6-i-Pr2C6H3)2]2 (5), which is reminiscent of that complex 2 in structure. Further reduction of 5 with magnesium anthracene afforded a lantern type quardruply-bonded complex Mo2[μ- η2：η2-anthracene][μ-η2-N(N-2,6-i-Pr2C6H3)2]2(6), where the anthracene bridges two Mo centers in an η4 fashion. However, reduction of 5 with magnesium powder resulted in a the isolation of a distorted paddlewheel quardruply-bonded dimolybdenum complex (MoH)[Cl2(μ-Mg(thf)2)] -Mo[μ-η2-N(N-2,6-i-Pr2C6H3)][μ-η2-N(N-2,6-i-Pr2C6H3)N(N-2-i-Pr-6-CH3CHCH2-C6H3)](7), from which a C-H bond cleavage of one of the isopropyl groups is observed.