Syntheses, Reactivity, Structures, and Dynamic Properties of Gyroscope-like Iron Carbonyl Complexes Based on Dibridgehead Diarsine Cages
Syntheses, Reactivity, Structures, and Dynamic Properties of Gyroscope-like Iron Carbonyl Complexes Based on Dibridgehead Diarsine Cages
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DOI：
10.1021/acs.organomet.6b00447
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发表时间：
2016-09-12
期刊：
影响因子：
2.8
通讯作者：
Gladysz, John A.
中科院分区：
文献类型：
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作者：
Lang, Georgette M.;Bhuvanesh, Nattamai;Gladysz, John A.
BrMg(CH2)(M)CH=CH2(m=4，a；5，b；6，c)与AsCl3(0.30当量)的反应得到Arine为((CH2)(M)CH=CH2)(3)(58-70%)，当添加到铁的三羰基源中时，生成反式Fe(CO)(3)(As((CH2)(M)CH-CH2)(3))(2)(66-70%)。用GRubbs催化剂(18mol%，CH2Cl2，回流)反应，然后加氢(ClRh(PPh3)(3)/60-80℃)，得到了理想的D3h对称性的陀螺仪状配合物Fe(CO)(3)(As((CH2)(N))(3)As)(4a-c，n=2m+2；41-59%/两步)。NO+BF4-加成得到等电子阳离子和等位阳离子[Tiebar在startFe(CO)(2)(NO)(As((CH2)(N))(3)As)]+BF4-(5a-c(+)BF4-；81-98%)和[H(OEt2)(2)]+barf-(barf=B(3，5-C6H3(CF3)(2))(4))得到氢化物络合物mer，反式[tiebar on startFe(CO)(3)(H)(as((CH2)(N))(3)tiebar over endas)]+barf-(6a-c+barf-；98-99%)。测定了4a-c和5b(+)BF(4-)的晶体结构。4c的计算结果表明，Fe(CO)3部分有足够的van der Waals间隙在As(CH2)(14)As键中旋转；4a的计算结果表明，较短的As(CH2)10As键阻碍了旋转。用VT核磁共振研究了这些络合物的旋转体动力学。在室温溶液中，5a(+)BF(4)(-)和6a(+)bar(F)(-)给出两组P(CH2)(n/2)~(13)C核磁共振信号(2：1)，而5b，c+BF4-和6b，c+Barf-只给出一组。在较低温度下，5b+BF4-和6b(+)bar(F)(-)的信号退缩。数据给出了Fe(CO)(2)(NO)(+)和Fe(CO)(3)(H)(+)转动的Delta H-双匕首/Delta S-双匕首的值(千卡/摩尔和eU)分别为7.7千卡/摩尔和5.4千卡/-22.7。这些屏障明显低于双膦类似物，与较长的铁砷对磷键一致，增加了二氮杂环笼子的内部尺寸。
Reactions of BrMg(CH2)(m)CH=CH2 (m = 4, a; 5, b; 6, c) and AsCl3 (0.30 equiv) give the arsines As((CH2)(m)CH=CH2)(3) (58-70%), which when added to iron tricarbonyl sources yield trans-Fe(CO)(3)(As((CH2)(m)CH-CH2)(3))(2) (66-70%). Reactions with Grubbs catalyst (18 mol %, CH2Cl2, reflux) and then hydrogenations (ClRh(PPh3)(3)/60-80 degrees C) afford gyroscope-like complexes trans-tiebar above startFe(CO)(3)(As((CH2)(n))(3)As) (4a-c, n = 2m + 2; 41-59%/two steps) of idealized D3h symmetry. Additions of NO+BF4- give the isoelectronic and isosteric cations [tiebar above startFe(CO)(2)(NO)(As((CH2)(n))(3)As)]+BF4- (5a-c(+) BF4-; 81-98%), and [H(OEt2)(2)]+BArf- (BArf = B(3,5-C6H3(CF3)(2))(4)) gives the hydride complexes mer,trans-[tiebar above startFe(CO)(3)(H)(As((CH2)(n))(3)tiebar above endAs)]+BArf- (6a-c+ BArf-; 98-99%). Crystal structures of 4a-c and 5b(+)BF(4-) are determined. That of 4c suggests enough van der Waals clearance for the Fe(CO)3 moiety to rotate within the As(CH2)(14)As linkages; that of 4a shows rotation to be blocked by the shorter As(CH2)10As linkages. The rotator dynamics in these complexes are probed by VT NMR. At ambient temperature in solution, 5a(+)BF(4)(-) and 6a(+)BAr(f)(-) give two sets of P(CH2)(n/2) 13C NMR signals (2:1), while 5b,c+BF4- and 6b,c+BArf- give only one. At lower temperatures the signals of 5b+BF4- and 6b(+)BAr(f)(-) decoalesce. The data give Delta H-double dagger/Delta S-double dagger values (kcal/mol and eu) of 7.7/-22.1 and 5.4/-22.7 for Fe(CO)(2)(NO)(+) and Fe(CO)(3)(H)(+) rotation. These barriers are distinctly lower than in diphosphine analogues, consistent with the longer iron-arsenic vs -phosphorus bonds increasing the interior dimensions of the diarsine cage.