title: A Family of Multiply Bonded Dimolybdenum Boraamidinates with the Formal Mo-Mo Bond Orders of 3, 4, 4.5, and 5.
abstract: A boraamidinato ligand [PhB(N-2,6-(i) Pr2 C6 H3 )2 ](2-) was employed to stabilize a new family of multiply bonded dimolybdenum complexes [MoCl(μ-κ(2) -PhB(N-2,6-(i) Pr2 C6 H3 )2 )]2 (4) and [Mo(μ-κ(2) -PhB(N-2,6-(i) Pr2 C6 H3 )2 )]2 (n-) (n=0 (5), 1 (6), 2 (7)), with the respective formal Mo-Mo bond orders of 3, 4, 4.5, and 5. Each metal center in 5-7 is two-coordinate with respect to the ligands. Of particular interest is the quadruply bonded dimolybdenum complex 5, featuring an unprecedented angular conformation. The bent Mo2 N4 core of 5 distorts toward planarity upon reduction. As a result, compound 7 features a planar Mo2 N4 core, while that of 6 is still bent but less significantly than that of 5. Additionally, the Mo-Mo bond lengths of 4-7 systematically decrease as the valency of the central Mo2 units decreases. Complex 7 features the shortest Mo-Mo bond length (2.0106(5) Å) yet reported.
authors.affiliation: Department of Chemistry and Frontier Research Center on Fundamental and Applied Sciences and Matters, National Tsing Hua University, 101, Sec. 2, Guang-Fu Road, Hsinchu, 300, Taiwan.
authors.forename: Duan-Yen
authors.initials: DY
authors.lastname: Lu
authors.affiliation: Department of Chemistry, National (Taiwan) Normal University, 88, Sec. 4, Ting-Chow Rd, Taipei, 116, Taiwan.
authors.forename: Ting-Shen
authors.initials: TS
authors.lastname: Kuo
authors.affiliation: Department of Chemistry and Frontier Research Center on Fundamental and Applied Sciences and Matters, National Tsing Hua University, 101, Sec. 2, Guang-Fu Road, Hsinchu, 300, Taiwan. yictsai@mx.nthu.edu.tw.
authors.forename: Yi-Chou
authors.initials: YC
authors.lastname: Tsai
keywords: bonding order; boraamidinate; molybdenum; multiple bonds; δ-bonds