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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Bulky cationic beta-diketiminate magnesium complexes
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Bulky cationic beta-diketiminate magnesium complexes

机译:庞大的阳离子β-二酮酸镁络合物

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Cationic beta-diketiminate Mg complexes with the bulky (BDI)-B-tBu ligand and the weakly coordinating anion B(C6F5)(4)(-) have been prepared by the reaction of ((BDI)-B-tBu)MgnBu with [Ph3C](+)[B(C6F5)(4)](-); (BDI)-B-tBu = CH[C(tBu)N-Dipp](2) and Dipp = 2,6-diisopropylphenyl. Their structures are compared to the previously reported cationic ((BDI)-B-Me)Mg+ complexes; (BDI)-B-Me = CH[C(Me)N-Dipp](2). Crystallization of [((BDI)-B-tBu)Mg](+)[B(C6F5)(4)](-) from chlorobenzene gave a unique ((BDI)-B-tBu)Mg+center dot ClC6H5 cation with a rather short Mg center dot center dot center dot Cl and consequently long C-Cl bond. Crystallization from chlorobenzene/arene solvent mixtures gave ((BDI)-B-tBu)Mg+center dot arene complexes (arene = benzene, toluene, m-xylene) but in the presence of mesitylene the chlorobenzene complex was formed. Due to the greater shielding of the metal, none of these complexes display Mg center dot center dot center dot(F5C6)(4)B- interactions. Crystal structures of the arene complexes show in all cases eta(2)-coordination of the arene ligands. Ring slippage from a more favorable eta(2)-coordination can be explained by the steric bulk of the (BDI)-B-tBu ligand. The smaller arenes, benzene and toluene, also bind to ((BDI)-B-tBu)Mg+ in bromobenzene solution. The Lewis acidity of these cationic Mg complexes was determined by the Gutmann-Beckett test. The acceptor number for ((BDI)-B-tBu)Mg+ (AN = 76.0) is substantially higher than that estimated for ((BDI)-B-Me)Mg+ (AN = 70.3). Calculation of the atomic NPA charges by DFT shows that the Mg2+ ion in ((BDI)-B-tBu)Mg+ is slightly more positively charged than the metal in ((BDI)-B-Me)Mg+, confirming its higher Lewis acidity. The lower benzene complexation energy calculated for ((BDI)-B-tBu)Mg(+)versus ((BDI)-B-Me)Mg+ is due to steric congestion of the metal in the ((BDI)-B-tBu)Mg+ cation which allows only for Mg center dot center dot center dot(eta(1))C6H6 instead of Mg center dot center dot center dot(eta
机译:用笨重(BDI)-B-TBU配体和弱协调阴离子B(C6F5)(4)( - )的阳离子β-二酮酸镁络合物已经通过((BDI)-B-TBU)MGNBU的反应制备[PH3C](+)[B(C6F5)(4)]( - ); (BDI)-B-TBU = CH [C(TBU)N-DIPP](2)和DIPP = 2,6-二异丙基苯基。将其结构与先前报道的阳离子((BDI)-B-ME)Mg +复合物进行比较; (bdi)-b-me = ch [c(me)n-dipp](2)。来自氯苯的[((BDI)-B-TBU)Mg](+)[B(C6F5)(4)]( - )的结晶得到了独特的((BDI)-B-TBU)Mg +中心点Clc6H5阳离子一个相当短的MG中心点中心点中心点CL和因此长的C-CL键合。从氯苯/芳烃溶剂混合物中结晶产生((BDI)-B-TBU)Mg +中心点芳烃配合物(Arene =苯,甲苯,甲苯二甲),但在乙烯苯二甲酸烯的存在下形成氯苯复合物。由于金属的屏蔽较大,这些复合物中的任何一个都没有显示MG中心点中心点中心点(F5C6)(4)B-相互作用。芳烃复合物的晶体结构在所有情况下显示ETA(2) - 芳烃配体的核心。来自更有利的ETA(2)的环形滑动可以通过(BDI)-B-TBU配体的空间大部分来解释。较小的芳烃,苯和甲苯,也结合((BDI)-B-TBU)Mg +在溴苯溶液中。这些阳离子Mg络合物的路易斯酸度由Gutmann-Beckett试验测定。 ((bdi)-b-tbu)mg +(a = 76.0)的受体编号基本上高于((bdi)-b-me)mg +(a = 70.3)的估计值。 DFT的原子NPA电荷的计算表明(((BDI)-B-TBU)Mg +中的Mg2 +离子比((BDI)-B-ME)Mg +中的金属略微充电,确认其较高的路易斯酸度。用于((BDI)-B-TBU)Mg(+)对((BDI)-B-ME)Mg +计算的低苯络合能量是((BDI)-B-TBU)中的空间拥塞MG +阳离子仅允许MG中心点中心点中心点(ETA(1))C6H6而不是MG中心DOT中心DOT中心点(ETA

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