Substituted N-picolylethylenediamines of the type (ArNHCH2CH2){(2-C5H4N)CH2}NR [R = Me, 4-CH2CH(C6H4)CH2, (2-C5H4N)CH2] and their transition metal(ii) halide complexes
作者:Christopher J. Davies、John Fawcett、Richard Shutt、Gregory A. Solan
DOI:10.1039/b505763a
日期:——
Alkylation of (ArNHCH2CH2)(2-C5H4N)CH2}NH with RX [RX = MeI, 4-CH2CH(C6H4)CH2Cl) and (2-C5H5N)CH2Cl] in the presence of base has allowed access to the sterically demanding multidentate nitrogen donor ligands, (2,4,6-Me3C6H2)NHCH2CH2}(2-C5H4N)CH2}NMe (L1), (2,6-Me3C6H3)NHCH2CH2}(2-C5H4N)CH2}NCH2(C6H4)-4-CHCH2
(L2) and (ArNHCH2CH2)(2-C5H4N)CH2}2N (Ar = 2,4-Me2C6H3L3a, 2,6-Me2C6H3L3b) in moderate yield. L3 can also be prepared in higher yield by the reaction of (NH2CH2CH2)(2-C5H4N)CH2}2N with the corresponding aryl bromide in the presence of base and a palladium(0) catalyst. Treatment of L1 or L2 with MCl2
[MCl2
= CoCl2·6H2O or FeCl2(THF)1.5] in THF affords the high spin complexes [(L1)MCl2]
(M = Co 1a, Fe 1b) and [(L2)MCl2]
(M = Co 2a, Fe 2b) in good yield, respectively; the molecular structure of 1a reveals a five-coordinate metal centre with L1 bound in a facial fashion. The six-coordinate complexes, [(L3a)MCl2]
(M = Co 3a, Fe 3b, Mn 3c) are accessible on treatment of tripodal L3a with MCl2. In contrast, the reaction with the more sterically encumbered L3b leads to the pseudo-five-coordinate species [(L3b)MCl2]
(M = Co 4a, Fe 4b) and, in the case of manganese, dimeric [(L3b)MnCl(µ-Cl)]2
(4c); in 4a and 4b the aryl-substituted amine arm forms a partial interaction with the metal centre while in 4c the arm is pendant. The single crystal X-ray structures of 1a, 3b·MeCN, 3c·MeCN, 4b·MeCN and 4c are described as are the solution state properties of 3b and 4b.
在碱存在下,(ArNHCH2CH2)(2-C5H4N)CH2}NH 与 RX [RX = MeI、4-CH2CH(C6H4)CH2Cl) 和 (2-C5H5N)CH2Cl] 发生烷基化反应,从而获得了立体要求较高的多叉氮供体配体、(2,4,6-Me3C6H2)NHCH2CH2}(2-C5H4N)CH2}NMe(L1)、(2、6-Me3C6H3)NHCH2CH2}(2-C5H4N)CH2}NCH2(C6H4)-4-CHCH2 (L2) 和 (ArNHCH2CH2)(2-C5H4N)CH2}2N (Ar = 2,4-Me2C6H3L3a, 2,6-Me2C6H3L3b) 的中等产率。在碱和钯 (0) 催化剂存在下,(NH2CH2CH2)(2-C5H4N)CH2}2N 与相应的芳基溴反应也可以制备出产率更高的 L3。在四氢呋喃中用 MCl2 [MCl2 = CoCl2-6H2O 或 FeCl2(THF)1.5]处理 L1 或 L2,可分别得到高自旋络合物 [(L1)MCl2](M = Co 1a,Fe 1b)和 [(L2)MCl2](M = Co 2a,Fe 2b),收率很高;1a 的分子结构显示出一个五配位金属中心,L1 以面状结合。用 MCl2 处理三足鼎立的 L3a 时,可以得到六配位的[(L3a)MCl2](M = Co 3a、Fe 3b、Mn 3c)配合物。相反,与立体性更强的 L3b 反应则会产生假五配位物种 [(L3b)MCl2](M = Co 4a、Fe 4b),就锰而言,则会产生二聚体 [(L3b)MnCl(µ-Cl)]2(4c);在 4a 和 4b 中,芳基取代的胺臂与金属中心形成部分相互作用,而在 4c 中,胺臂是悬垂的。本文描述了 1a、3b-MeCN、3c-MeCN、4b-MeCN 和 4c 的单晶 X 射线结构,以及 3b 和 4b 的溶液状态特性。