Synthesis and characterisation of half-sandwich tantalum compounds in oxidation states (I)–(V): tertiary phosphine, acetylene, butadiene, carbonyl, and oxo derivatives. X-Ray crystal structures of [Ta(C<sub>5</sub>Me<sub>5</sub>)Cl<sub>3</sub>(PMe<sub>3</sub>)] and [Ta(C<sub>5</sub>Me<sub>5</sub>)Cl<sub>2</sub>(CO)<sub>2</sub>(PMe<sub>3</sub>)]
作者:Vernon C. Gibson、Terence P. Kee、William Clegg
DOI:10.1039/dt9900003199
日期:——
61% yield. Although stable indefinitely at room temperature, (15) converts upon warming at 100 °C to the trans isomer. The reaction has been monitored by 1H n.m.r. spectroscopy giving a pseudo first-order rate constant of 9.9(1)× 10–5s–1. Reduction of (14) with sodium amalgam in the presence of CO (1.5 atm) gives [Ta(C5Me5)(CO)4](17) in 65% yield. Complex (17) can also be obtained in 47% yield in a
半三明治叔膦钽化合物[Ta(C 5 H 5)Cl 3(PMe 3)](3),[Ta(C 5 H 5)Cl 2(PMe 3)3 ](6),[Ta( C 5 Me 5)Cl 2(PMe 3)2 ](7)和[Ta(C 5 Me 5)Cl 3(dmpe)](5)(dmpe = Me 2 PCH 2 CH 2 PMe 2)是通过在膦存在下用四氢呋喃(thf)中的镁处理[Ta(C 5 R 5)Cl 4 ](R = H或Me)制备的。化合物(3),(6)和(7)在氯碳中分解,得到四氯化物[Ta(C 5 R 5)Cl 4(PMe 3)]。化合物(7)还在烃溶剂中分解,得到产物混合物,从中可以选择性地结晶[Ta(C 5 Me 5)Cl 3(PMe 3)](4)。该X在正交空间组P 2 1 2 1 2 1中确定了(4)的X射线晶体结构,并揭示了四脚钢琴凳的几何形状。化合物(7)反应与RC器CPh(R = H或pH),得到已知乙炔配合物[钽(C
Bidentate metalloligands containing the phosphinocyclopentadienyl ligand. New heterobimetallic complexes and crystal structure of (C5Me5)(C5H4PPh2)Ta(CO)(μ-PPh2)Cr(CO)4
Cp*(C5H4PPh2)TaLn [Ln = (H)3, (H)(CO), (H)2(PPh2), (CO)(PPh2)] 2, 3, 4b, 5b containing the diphenylphosphinocyclopentadienyl ligand have been prepared and characterized. The trihydride complex 2 was obtained by reduction of the dichloride compound Cp*(C5H4PPh2)TaCl2 1. Treatment of 2 under a CO atmosphere at 140 °C in decane affords the monohydride complex 3. Compounds2 and 3 easily react with chlorophosphines
四种新型金属配体Cp *(C 5 H 4 PPh 2)TaL n [L n =(H)3,(H)(CO),(H)2(PPh 2),(CO)(PPh 2)]已经制备并表征了包含二苯基膦基环戊二烯基配体的2、3、4b,5b。通过还原二氯化物化合物Cp *(C 5 H 4 PPh 2)TaCl 2获得三氢化物络合物2。1.在140℃的CO气氛中于癸烷中处理2,得到一价氢化物配合物3.化合物2和3容易与氯膦反应,分别产生磷衍生物4b和5b。所有这些金属配体起单齿和/或螯合双齿配体的作用。研究了它们对不饱和有机金属片段[M'(CO)5 ]或[M'(CO)4 ](M'= Cr,W)的反应性。Cp的X射线晶体结构*(C 5 H ^ 4 PPH 2)的Ta(CO)(μ-PPH 2)C R(CO)4被报告10CR。
A new class of reactive, transition metal–metal doubly-bonded organodimetallic complexes: synthesis, structure, and reactivity of (η-C<sub>5</sub>Me<sub>4</sub>R)<sub>2</sub>Ta<sub>2</sub>(µ-X)<sub>4</sub>(R = Me, Et; X = Cl, Br)
作者:Ching Ting、Norman C. Baenziger、Louis Messerle
DOI:10.1039/c39880001133
日期:——
Reduction of (η-C5Me4R)TaX4(R = Me, Et; X = Cl, Br) with two equivalents of sodium amalgam in toluene affords the reactive tantalum–tantalum doubly-bonded species (η-C5Me4R)2Ta2(µ-X)4 in 70% yield; the solid-state structure of (C5Me5)2Ta2(µ-Br)4 consists of a TaTa double bond, 2.748(2)Å in length, bridged symmetrically by four bromide ligands.
的(η-C还原5我4 R)税4(R =甲基,乙基; X =氯,溴),在甲苯钠汞齐的两个当量,得到反应性钽-钽双重键合的物种(η-C 5我4 R)2 Ta 2(µ-X)4的产率为70%;(C 5 Me 5)2 Ta 2(µ-Br)4的固态结构由Ta Ta双键组成,其长度为2.748(2)Å,由四个溴化物配体对称地桥接。
Bent-sandwich derivatives of tantalum bearing one or two pentamethylcyclopentadienyl ligands
作者:Vernon C. Gibson、John E. Bercaw、William J. Bruton、Robert D. Sanner
DOI:10.1021/om00136a023
日期:1986.5.1
Experimental and Computational Evaluation of Tantalocene Hydrides for C–H Activation of Arenes
作者:Steven M. Rehbein、Matthew J. Kania、Sharon R. Neufeldt
DOI:10.1021/acs.organomet.1c00308
日期:2021.8.9
aromatic C–H activation, but that formation of a π-complex with Cp2TaH directs preferential aromatic C–H activation. Analogous complexes containing the less labile permethylated ligand Cp* (Cp* = η5-C5Me5) were also evaluated for their ability to catalyze H/D exchange with benzene-d6, but these complexes are less active than Cp2TaH3. DFT calculations indicate that the methyl groups of Cp* disfavor π-coordination
半个世纪前,据报道,钽茂氢化物(尤其是 Cp 2 TaH 3,其中 Cp = η 5 -C 5 H 5)可催化与芳烃的 H/D 交换。然而,对开创性报告的跟进很少,关于这种化学的许多问题仍未得到解答。为了更好地评估钽氢化物在涉及 C-H 活化过程中的潜力,我们对这些配合物进行了一系列实验和计算研究。密度泛函理论 (DFT) 计算支持芳烃 C-H 活化机制,包括瞬态 Ta III处的氧化加成,而不是 Ta V处的 σ 键复分解机制. 对Cp 2 TaH 3与苯-d 6反应的热和光化学条件进行了比较,发现H/D 交换在热条件下较快。在与甲苯的反应中,Cp 2 TaH 3 会激活芳香族 C (sp 2 ) -H 键,但不会激活苄键。DFT 计算表明,在 Ta III上的苄基 C-H 活化具有类似于芳香族 C-H 活化的势垒,但与 Cp 2 TaH形成 π 络合物会引导优先芳香族 C-H 活化。含有不稳定的全甲基化配体