Complexes of (arylimido)vanadium(V). Synthetic, structural, spectroscopic, and theoretical studies of V(Ntol)Cl3 and derivatives
Complexes of (arylimido)vanadium(V). Synthetic, structural, spectroscopic, and theoretical studies of V(Ntol)Cl3 and derivatives
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(芳基亚氨基)钒(V)的络合物。
DOI：
10.1021/ja00258a026
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发表时间：
1987
影响因子：
15
通讯作者：
E. Maatta
中科院分区：
文献类型：
--
作者：
D. Devore;J. Lichtenhan;F. Takusagawa;E. Maatta
VOCl_3与各种对位取代芳基异氰酸酯p-XC_6 H_4 NCO（X= CH_3，CF_3，OCH_3，F，Cl，Br）反应，得到相应的（芳基亚氨基）钒（V）配合物V（NC_6 H_4X）C_（13）。对甲苯酰亚胺络合物V（Ntol）Cl 3，1显示出广泛的衍生物化学。1与刘易斯碱反应得到单加成产物如V（Ntol）Cl 3（THF）和V（Ntol）Cl 3（PPh 3）。1的氯化物配体容易参与亲核取代反应，提供一系列烷氧基化合物（V（Ntol）Cl 3-n（O-r-Bu）n：n= 1，2;= 2，3;= 3，4），芳氧基化合物（V（Ntol）Cl 3-n（OAr）n：n= 1，5;= 2，6;= 3，7; Ar= 2，6-C6 H3（CH 3）2）和有机金属（V（Ntol）Cl 3-n（CH 2SiMe 3）n：n= 1，8; n = 2，9; n= 3，10;（N5-C5 H5）V（Ntol）Cl 2，11）衍生物。配合物1-10的电子光谱在近红外区有一个吸收峰。1000 nm。配合物1-7还显示出在光谱的可见光区的第二吸收，并且该吸收的能量随着基础配体供体原子的电负性的增加而增加。测定了这些（芳基亚氨基）钒（V）配合物的~（51）V NMR谱，~（51）V化学位移范围为1700 ppm。51 V化学位移也与基础配体给体原子的电负性相关。最低场位置为10（3（51 V）=+1048），当纯供电子烷基被电负性增加和供电子能力增加的配体取代时，发生< 5（51 V）到更高场的规律性进展。配合物1-10的电子和~（51）V核磁共振谱与化学结构的相关性主要由顺磁屏蔽贡献来解释。用扩展的Hückel方法对几种模型配合物进行了计算，解释了配合物1-10和含氧和烷基亚氨基配体的钒（V）配合物的51 V化学位移的电子因素。X-射线晶体结构测定表明，配合物6在固态下具有二聚体结构。每个钒原子的centrophilicdimmer是协调在一个三角双锥几何形状，与终端tolylimido配体和桥接芳氧基占据顶端网站。在VOV桥键合中存在确定的不对称性。晶体数据6：单斜晶系，12/c·，a= 24.937（5），B= 10.790（2），c= 16.662（3）A; ε = 97.18（2）; Z= 8。本文报道了三氯-（对甲苯亚氨基）钒（V），V（Ntol）Cl_（3，2）可以很容易地被官能化，得到各种（对甲苯亚氨基）钒（V）的烷氧化物、芳氧化物和有机膦衍生物。这一系列化合物的广泛应用使我们开始描述不同配位环境对（有机酰亚胺）钒（V）配合物51 V NMR特征的影响。借助于扩展的Hückel计算研究了这些物种的~（51）VNMR结果与电子光谱之间的相关性，并提供了与氧代和烷基酰亚胺配体的相关钒（V）配合物的示例性比较。我们还报道了一个二聚体的分子结构，
The reactions of VOCl3 with various para-substituted aryl isocyanates, p-XC6H4NCO (X= CH3, CF3, OCH3, F, Cl, Br), afford the corresponding (arylimido) vanadium (V) trichloride species, V (NC6H4X) C13. The p-tolylimido complex, V (Ntol) Cl3, 1, displays an extensive derivative chemistry. The reaction of 1 with Lewis bases affords monoaddition products such as V (Ntol) Cl3 (THF) and V (Ntol) Cl3 (PPh3). The chloride ligands of 1 readily participate in nucleophilic substitution reactions, affording a range of alkoxide (V (Ntol) Cl3_ „(0-r-Bu)„: n= 1, 2;= 2, 3;= 3, 4), aryloxide (V (Ntol) Cl3_ „(OAr)„: n= 1, 5;= 2, 6;= 3, 7; Ar= 2, 6-C6H3 (CH3) 2), and organometallic (V (Ntol) Cl3_ „(CH2SiMe3)„: n= 1, 8;= 2, 9; n= 3, 10;(r¡ 5-C5H5) V (Ntol) Cl2, 11) derivatives. The electronic spectra of complexes 1—10 each display an absorption in the near-IR regionat ca. 1000 nm. Complexes 1-7 also display a second absorption in the visible region of the spectrum, and the energy of this absorption increases with increasing electronegativity of the basal ligand donor atoms. The 51V NMR spectra of these (arylimido) vanadium (V) complexes have been determined; 51V chemical shifts in this series span a range of 1700 ppm. The 51V chemical shifts also correlate with the electronegativity of the basal ligand donor atoms. The lowest field position is observed for 10 (3 (51V)=+ 1048), and a regular progression of< 5 (S1V) to higher field occurs as the purely-donating alkyl groups are replaced by ligands of increased electronegativity and increased 7r-donating ability. Theobserved correlations of the electronic and 51V NMR spectra with the chemical constitutions of complexes 1-10 are explained in terms of a dominating paramagnetic shielding contribution. Extended Hückel calculations on several model complexes are used to provide an explanation of the electronic factors underlying the disparate 51V chemical shifts observed for complexes 1-10 and related vanadium (V) complexes bearing oxo and alkylimido ligands. AnX-ray crystal structure determination reveals that complex 6 possesses a dimeric structure in the solid state. Each vanadium atom in the centrosymmetricdimer is coordinated in a trigonal-bipyramidal geometry, with a terminal tolylimido ligand and a bridging aryloxide group occupying the apical sites. There is a decided asymmetry in the VOV bridge bonding. Crystal data for 6: monoclinic, 12/c·, a= 24.937 (5), b= 10.790 (2), c= 16.662 (3) A; ß= 97.18 (2); Z= 8.Although a number of vanadium (V) organoimido complexes are now known, 1 these species are generally insular and lack a systematic derivative chemistry. We now report that trichloro-(p-tolylimido) vanadium (V), V (Ntol) Cl3, 2 can be readily functionalized to afford a variety of alkoxide, aryloxide, and or-ganometallic derivatives of (p-tolylimido) vanadium (V). The wide range of compounds accessible in this series has allowed us to begin to delineate theinfluence of various coordination environments on the 51V NMR characteristics of (organoimido) vanadium (V) complexes. Correlations between the 51V NMR results and the electronic spectra of these species are examined with the aid of extended Hückel calculations and provide an illustrative com-parison to related vanadium (V) complexes of oxo and alkylimido ligands. We also report the molecular structure of a dimeric