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首页> 外文期刊>Inorganic Chemistry: A Research Journal that Includes Bioinorganic, Catalytic, Organometallic, Solid-State, and Synthetic Chemistry and Reaction Dynamics >Reactions of the dirhenium(II) complex Re2Cl4(mu-dppm)(2) with pyridinecarboxylic acids. Examples of bidentate O,O versus N,O coordination and tridentate O,N,O coordination and structural isomers that contain the pyridine-2,6-dicarboxylate ligand
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Reactions of the dirhenium(II) complex Re2Cl4(mu-dppm)(2) with pyridinecarboxylic acids. Examples of bidentate O,O versus N,O coordination and tridentate O,N,O coordination and structural isomers that contain the pyridine-2,6-dicarboxylate ligand

机译：dir（II）配合物Re2Cl4（mu-dppm）（2）与吡啶羧酸的反应。包含吡啶2,6-二羧酸酯配体的二齿O，O与N，O配位以及三齿O，N，O配位和结构异构体的例子

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摘要

Pyridine-2-carboxylic acid, pyridine-2,3-dicarboxylic acid, and pyridine-2,4-dicarboxylic acid or their [(Ph3P)(2)N](+) salts react with the triply bonded dirhenium(II) complex Re2Cl4(mu-dppm)(2) (dppm = Ph2PCH2PPh2) in refluxing ethanol to afford unsymmetrical substitution products of the type Re-2(eta(2)-N,O)Cl-3(mu-dppm)(2), where N,O represents a chelating pyridine-2-carboxylate ligand (N,O = O2C-2-C5H4N (1), O2C-2-C5H3N(-3-CO2Et) (3), or O2C-2-C5H3N(-4-CO2H) (4)). The carboxylate groups in the 3- and 4- positions are not bound to the metal centers; in the case of 3 this group undergoes esterification in the refluxing ethanol solvent. Structure determinations have shown that 1, 3, and 4 possess similar structures in which there is an axial Re-O (carboxylate) bond (collinear with the RedropRe bond) and the mu-dppm ligands are bound in a trans,cis fashion to the two Re atoms which have the ligand atom arrangement [P2NOClReReCl2P2] The tridentate dianionic pyridine-2,6-dicarboxylate ligand (dipic) reacts with Re2Cl4(mu-dppm)(2) in ethanol at room temperature to give a compound Re-2(dipic)Cl-2(mu-dppm)(2) (6) in which the dipic ligand is bound in a symmetrical eta(3)-(O,N,O), fashion to one Re atom, with the N atom in an axial position (collinear with the RedropRe bond) and with preservation of the same trans,trans coordination of the mu-dppm ligands that is present in Re2Cl4(mu-dppm)(2). Under reflux conditions, this kinetic product isomerizes to the thermodynamically favored isomer 5 with an unsymmetrical structure in which the dipic ligand chelates to one Re atom (as in 1, 3, and 4) and uses its other carboxylate group to bridge to the second Re atom. The isomerization of 6 to 5, which also results in a change in the coordination of the pair of mu-dppm ligand to trans,cis, is believed to occur by a partial "merry-go-round" process, a mechanism that probably explains the structures of the thermodynamic products 1, 3, and 4. The reaction of Re2Cl4(mu-dppm)(2) with pyridine-3-carboxylate gives the trans isomer of Re-2(mu:eta(2)-O2C-3-C5H4N)(2)-Cl-2(mu-dppm)(2) (2) in which a pair of carboxylate bridges are present and the pyridine N atom is not coordinated. Single-crystal X-ray structural details are reported for 1-6. [References: 22]
机译：吡啶-2-羧酸，吡啶-2,3-二羧酸和吡啶-2,4-二羧酸或它们的[（Ph3P）（2）N]（+）盐与三键结合的（II）络合物反应Re2Cl4（mu-dppm）（2）（dppm = Ph2PCH2PPh2），在回流的乙醇中提供Re-2（eta（2）-N，O）Cl-3（mu-dppm）（2）类型的不对称取代产物，其中N，O代表螯合吡啶-2-羧酸酯配体（N，O = O2C-2-C5H4N（1），O2C-2-C5H3N（-3-CO2Et）（3）或O2C-2-C5H3N（- 4-CO 2 H）（4））。 3-位和4-位的羧酸根不与金属中心键合;在3的情况下，该基团在回流的乙醇溶剂中进行酯化。结构确定表明，1、3和4具有相似的结构，其中存在轴向Re-O（羧酸根）键（与RedropRe键共线），并且mu-dppm配体以反式，顺式方式与两个具有配体原子排列的Re原子[P2NOClReReCl2P2]三齿双阴离子吡啶2,6-二羧酸酯配体（dipic）在室温下与Re2Cl4（mu-dppm）（2）在乙醇中反应，得到化合物Re-2（ diic）Cl-2（mu-dppm）（2）（6），其中didic配体以对称的eta（3）-（O，N，O）形式与一个Re原子键合，N原子位于轴向位置（与RedropRe键共线）并保留Re2Cl4（mu-dppm）（2）中mu-dppm配体的相同反式，反式配位。在回流条件下，该动力学产物异构化为具有不对称结构的热力学上有利的异构体5，其中二元配体螯合至一个Re原子（如1、3和4中所示），并使用其另一个羧酸酯基桥接至第二个Re原子。 6至5的异构化，也导致mu-dppm配体对反式，顺式的配位变化，据认为是通过部分“旋转木马”过程发生的，这种机制可能解释了热力学产物1、3和4的结构。Re2Cl4（mu-dppm）（2）与吡啶-3-羧酸酯的反应得到Re-2（mu：eta（2）-O2C-3 -C 5 H 4 N）（2）-Cl-2（μ-dppm）（2）（2），其中存在一对羧酸盐桥，并且吡啶N原子不配位。单晶X射线的结构细节报告为1-6。 [参考：22]

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