Aryl-Containing Chelates and Amine Debenzylation to Afford 1,3-Di-2-pyridyl-2-azaallyl (smif): Structures of {κ-C,N,N2py-(2-pyridylmethyl)2N(CH2(4-tBu-phenyl-2-yl))}FeBr and (smif)CrN(TMS)2
Aryl-Containing Chelates and Amine Debenzylation to Afford 1,3-Di-2-pyridyl-2-azaallyl (smif): Structures of {κ-C,N,N2py-(2-pyridylmethyl)2N(CH2(4-tBu-phenyl-2-yl))}FeBr and (smif)CrN(TMS)2
复制标题
DOI：
10.1021/ic901329z
复制
发表时间：
2009-12-21
影响因子：
4.6
通讯作者：
Lobkovsky, Emil B.
中科院分区：
文献类型：
--
作者：
Frazier, Brenda A.;Wolczanski, Peter T.;Lobkovsky, Emil B.
芳基溴配体前体已被制备，具有提供四齿螯合物（2-吡啶甲基）（3-x）N（CH 2 - 2-芳基）（x）（x = 1，2）的潜力，所述四齿螯合物含有有望赋予关于第一行过渡金属的更强场的金属-芳基键。通过与Ni（COD）（2）的氧化加成反应，得到两种抗磁性Ni（II）配合物：（kappa-C，N，N-py-（2-吡啶甲基）N（CH_2（4-Bu-t-phenyl））（CH_2（4-Bu-t-phenyl））} NiBr（1-Ni）和{（kappa-C，N，N-2（py）-（2-吡啶甲基）（2）N（CH_2（4-Bu-t-phenyl））} NiBr（2-Ni），产率分别为96%和67%。通过还原加合物{kappa-N，N-2（py）-（2-吡啶基甲基）（2）N（CH 2（4-Bu-t-苯基-2-Br））} FeBr 2（3-Fe），将这些合成努力扩展到铁，以91%的产率得到{kappa-C，N，N-2（py）-（2-吡啶基甲基）（2）N（CH 2（4-Bu-t-苯基-2-Br））} FeBr 2（2-Fe，X-射线）。5-配位2-Fe具有赝tbp结构，SQUID磁测量表明它是S = 2，具有显著的零场分裂（zero-field splitting）。2Fe最初是通过氧化加成到Fe {N（TMS）（2））（2）（THF）上，在还原成"Fe（0）"和2Fe {N（TMS）（2）}（3）后制备的，但是当用Cr {N（TMS）（2）}（2）（THF）（2）尝试该方法时，氮杂烯丙基络合物{kappa-N，N-2（py）-1，3-联吡啶基-2-氮杂烯丙基} CrN（TMS）（2）（（smif）CrN（TMS）（2），4-Cr，X射线），而是通过胺脱苄基化形成（> 50%）。另一种途径是将1，3-二-2-吡啶基-2-氮杂丙烯加成到Cr {N（TMS）（2）}（2）（THF）（2）中，得到4-Cr，产率为74%。伪正方形平面4-Cr也是S = 2（SQUID），具有显著的ε。联吡啶氮烯丙基配体"smif"通过配体内675 nm（λ = 15 000 M（-1）cm（-1））和396 nm（λ = 27 000 M（-1）cm（-1））的带赋予4-Cr显著的光密度。的螯合物的有效领域进行了讨论，并给出了比较smif等电子NHC配体。
Aryl-bromide ligand precursors have been prepared with the potential to afford tetradentate chelates (2-pyridylmethyl)(3-x)N(CH2-2-Aryl)(x)(x = 1, 2) containing metal-aryl linkages that promise to impart stronger fields about first row transition metals. Oxidative addition to Ni(COD)(2) afforded two diamagnetic Ni(II) complexes, (kappa-C,N,N-py-(2-pyridylmethyl)N(CH2(4-Bu-t-phenyl-2-yl))(CH2(4-Bu-t-phenyl-2-Br))}NiBr (1-Ni) and {(kappa-C,N,N-2(py)-(2-pyridylmethyl)(2)N(CH2(4-Bu-t-phenyl-2-yl))}NiBr (2-Ni) in 96% and 67% yield, respectively. Extending these synthetic efforts to iron provided {kappa-C,N,N-2(py)-(2-pyridylmethyl)(2)N(CH2(4-Bu-t-phenyl-2-yl))}FeBr (2-Fe, X-ray) in 91% yield via reduction of an adduct, {kappa-N,N-2(py)-(2-pyridylmethyl)(2)N(CH2(4-Bu-t-phenyl-2-Br))}FeBr2 (3-Fe). 5-Coordinate 2-Fe possessed a pseudo-tbp structure, and SQUID magnetometry showed it to be S = 2 with significant zero field splitting (ZFS). 2Fe was initially prepared via oxidative addition to Fe{N(TMS)(2))(2)(THF) upon disproportionation to "Fe(0)" and 2 Fe{N(TMS)(2)}(3), but when this approach was attempted with Cr{N(TMS)(2)}(2)(THF)(2), the azaallyl complex {kappa-N,N-2(py)-1,3-dipyridyl-2-azaallyl}CrN(TMS)(2) ((smif)CrN(TMS)(2), 4-Cr, X-ray), formed instead (>50%) via amine debenzylation. An alternative route consisting of addition of 1,3-di-2-pyridyl-2-azapropene to Cr{N(TMS)(2)}(2)(THF)(2) afforded 4-Cr in 74% yield. Pseudo-square planar 4-Cr was also S = 2 (SQUID) with marked ZFS. The dipyridylazaallyl ligand "smif" imparts a remarkable optical density to 4-Cr via intraligand bands at 675 nm (epsilon similar to 15 000 M(-1)cm(-1)) and 396 nm (epsilon similar to 27 000 M(-1)cm(-1)). The effective fields of the chelate complexes are discussed, and a comparison of smif to isoelectronic NHC ligands is given.