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首页> 外文期刊>Organometallics >Synthesis, structure, and ligand exchange reactions of tetramethyleneethane complexes of cobalt
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Synthesis, structure, and ligand exchange reactions of tetramethyleneethane complexes of cobalt

机译：钴的四亚甲基乙烷配合物的合成，结构和配体交换反应

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The synthesis of (η~3:η~3-TME)[Co(CO) _3]_2 (1) was achieved using 2,3-bis(bromomethyl)-1,3- butadiene (TMEBr_2) as the tetramethyleneethane (TME) ligand precursor and Na[Co(CO)_4]. Solution NMR studies suggested an η~3:η~3-configuration, which has been confirmed in the solid state by single-crystal X-ray diffraction studies. The series of complexes (η~3:η~3-TME)[Co(CO)_2PR _3]_2 (R = Me, 2; R = Et, 3; R = n-Bu, 4; R = Ph, 5; R = OPh, 6) were also synthesized by ligand exchange reactions, demonstrating that only one carbonyl may be exchanged for a phosphine group on each metal center. The η~3:η~3-configuration of the tetramethyleneethane ligand in these complexes was determined by crystallographic studies. The effect of the electron-donating properties of PR_3 was studied by cyclic voltammetry (CV) and infrared spectroscopy. The greatest degree of electron donation was seen when R = Et (3) and lowest when R = Ph (5) or R = OPh (6). Electronic communication between the metal centers was observed by CV. The chemical oxidation of 1 resulted in a highly unstable species that decomposed to {[(CO)_2Co]TME[Co(CO) _3]}~+[BF_4]~- (1~+d), determined by its crystal structure. The synthesis of (η~4: η~4-TME)[CoCp*]_2 (7) has been achieved using a dipotassium 2,3-bis(methylene)-1,3-butanediyl (TMEK_2) synthon. NMR studies suggested that 7 adopts an unusual η~4:η~4- configuration, which was confirmed with the aid of crystallographic studies. DFT calculations were performed in order to rationalize the bonding for 1, 7, and hypothetical (η~4:η~4-TME)[CoCp]_2 (8). The large energy difference between the two coordination isomers 1 and 1a confirmed the η~3:η~3-configuration. For isomers 7/7a and 8/8a, the energy difference between the two isomers (ca. 15 kJ mol ~(-1)) is in favor of the η~4:η~4- configuration. For complexes 1~+ and 8~+, the calculations suggested complete delocalization on the system when one electron was removed.
机译：（η〜3：η〜3-TME）[Co（CO）_3] _2（1）的合成使用2,3-双（溴甲基）-1,3-丁二烯（TMEBr_2）作为四亚甲基乙烷（TME） ）配体前体和Na [Co（CO）_4]。溶液NMR研究表明η〜3：η〜3-构型，已通过单晶X射线衍射研究确认为固态。一系列配合物（η〜3：η〜3-TME）[Co（CO）_2PR _3] _2（R = Me，2; R = Et，3; R = n-Bu，4; R = Ph，5 ; R ＝ OPh，6）也通过配体交换反应合成，表明每个金属中心上的膦基只能交换一个羰基。通过晶体学研究确定这些配合物中四亚甲基乙烷配体的η〜3：η〜3-构型。通过循环伏安法（CV）和红外光谱研究了PR_3的给电子性质的影响。当R = Et（3）时，可以看到最大程度的电子捐赠;而当R = Ph（5）或R = OPh（6）时，则可以看到最低程度的电子捐赠。 CV观察到金属中心之间的电子通信。 1的化学氧化导致高度不稳定的物质，该物质分解为{[（（CO）_2Co] TME [Co（CO）_3]}〜+ [BF_4]〜-（1〜+ d），具体取决于其晶体结构。 （η〜4：η〜4-TME）[CoCp *] _ 2（7）的合成已使用2,3-双（亚甲基）-1,3-丁二基（TMEK_2）双钾合成。 NMR研究表明7具有不寻常的η〜4：η〜4-构型，这已通过晶体学研究得以证实。进行DFT计算是为了合理化1、7和假设的（η〜4：η〜4-TME）[CoCp] _2（8）的键合。两个配位异构体1和1a之间的大能量差证实了η〜3：η〜3-构型。对于异构体7 / 7a和8 / 8a，两种异构体之间的能量差（约15 kJ mol〜（-1））有利于η〜4：η〜4-构型。对于1〜+和8〜+的配合物，计算表明当一个电子被除去时，在系统上完全离域。

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