Journal of Molecular Modeling ( IF 2.1 ) Pub Date : 2022-01-20 , DOI: 10.1007/s00894-021-05009-3 Chongyao Song 1 , Qifa Liu 1 , Wenqian Chen 1 , Xiaohong Chen 1 , Rong Jin 1 , Quan Du 1 , Yaoming Xie 2 , R Bruce King 2
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The structures and energetics of the binuclear cyclobutadiene vanadium carbonyls (C4H4)2V2(CO)n (n = 8, 7, 6, 5, 4, 3, 2) have been investigated by density functional theory (DFT). The lowest energy (C4H4)2V2(CO)8 structure consists of two C4H4V(CO)4 units linked by a V-V single bond of length 3.4 Å. The two lowest energy (C4H4)2V2(CO)7 structures also have formal V-V single bonds. The “extra” two electrons to give each vanadium atom in these heptacarbonyls the favored 18-electron configuration can come from either an agostic C-H-V interaction activating a hydrogen atom from one of the cyclobutadiene rings or from a four-electron donor bridging η2-µ-CO group with a short V–O distance. The lowest energy (C4H4)2V2(CO)6 structure has a formal V≡V triple bond of length 2.52 Å similar to the V≡V triple bond of length 2.46 Å found in the experimentally known cyclopentadienyl derivative (η5-C5H5)2V2(CO)5. The lowest energy structures for the more highly unsaturated (C4H4)2V2(CO)n (n = 5, 4, 3, 2) have at least two four-electron donor bridging η2-µ-CO groups and a vanadium-vanadium bond order sufficient to give each vanadium atom at least a 16-electron configuration.
Graphical abstract
The structures and energetics of the binuclear cyclobutadiene vanadium carbonyls (C4H4)2V2(CO)n (n = 8, 7, 6, 5, 4, 3, 2) have been investigated by density functional theory. The two lowest energy (C4H4)2V2(CO)7 structures include one with an agostic C-H-V interaction activating a hydrogen atom from one of the cyclobutadiene rings and another with a four-electron donor bridging η2-µ-CO group with a short V–O bonding distance.
中文翻译：
不饱和双核钒羰基衍生物中桥接环丁二烯配体的碳氢键活化
通过密度泛函理论 (DFT) 研究了双核环丁二烯钒羰基化合物 (C 4 H 4 ) 2 V 2 (CO) n ( n = 8, 7, 6, 5, 4, 3, 2) 的结构和能量学. 最低能量 (C 4 H 4 ) 2 V 2 (CO) 8结构由两个 C 4 H 4 V(CO) 4单元组成，它们通过一个长度为 3.4 Å 的 VV 单键连接。两个最低能量(C 4 H 4 ) 2 V 2 (CO) 7结构也有正式的 VV 单键。使这些七羰基化合物中的每个钒原子具有有利的 18 电子构型的“额外”两个电子可以来自于激活环丁二烯环之一的氢原子的前向 CHV 相互作用或来自桥接 η 2 -μ的四电子供体-CO 组，V-O 距离短。最低能量 (C 4 H 4 ) 2 V 2 (CO) 6结构具有长度为 2.52 Å 的正式 V≡V 三键，类似于在实验上已知的环戊二烯基衍生物 (η) 中发现的长度为 2.46 Å 的 V≡V 三键5 - C 5 H 5 ) 2 V 2(CO) 5 . 更高不饱和度 (C 4 H 4 ) 2 V 2 (CO) n ( n = 5, 4, 3, 2) 的最低能量结构具有至少两个桥接 η 2 -µ-CO 基团的四电子供体和足以使每个钒原子至少具有 16 个电子构型的钒-钒键序。
图形概要
通过密度泛函理论研究了双核环丁二烯钒羰基化合物(C 4 H 4 ) 2 V 2 (CO) n ( n = 8, 7, 6, 5, 4, 3, 2)的结构和能量学。两种最低能量 (C 4 H 4 ) 2 V 2 (CO) 7结构包括一种具有从一个环丁二烯环中激活氢原子的非活性 CHV 相互作用和另一种具有桥接 η 2 -μ-CO的四电子供体具有短 V-O 键距的组。
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