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Nickel(II)-mediated cyanamide–pyrazole coupling highlights distinct reactivity of NCNR2 and NCR nitrile ligands
New Journal of Chemistry ( IF 3.3 ) Pub Date : 2020-04-06 , DOI: 10.1039/d0nj00704h Lev E. Zelenkov 1, 2, 3, 4 , Maxim L. Kuznetsov 1, 2, 3, 4, 5 , Elena V. Andrusenko 1, 2, 3, 4 , Margarita S. Avdontceva 2, 3, 4, 6 , Galina L. Starova 1, 2, 3, 4 , Nadezhda A. Bokach 1, 2, 3, 4 , Vadim Yu. Kukushkin 1, 2, 3, 4
New Journal of Chemistry ( IF 3.3 ) Pub Date : 2020-04-06 , DOI: 10.1039/d0nj00704h Lev E. Zelenkov 1, 2, 3, 4 , Maxim L. Kuznetsov 1, 2, 3, 4, 5 , Elena V. Andrusenko 1, 2, 3, 4 , Margarita S. Avdontceva 2, 3, 4, 6 , Galina L. Starova 1, 2, 3, 4 , Nadezhda A. Bokach 1, 2, 3, 4 , Vadim Yu. Kukushkin 1, 2, 3, 4
Affiliation
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The reaction between pyrazole (PzH), the N,N-disubstituted cyanamides NCNR2 (R2 = Me2, Et2, C4H8, C5H10, C5H10O), and the nickel salts NiX2·nH2O (X = NO3, OTf, ClO4, Cl, OTs, n = 6; Br, n = 3) affords complexes featuring ligands derived from the NiII-mediated cyanamide–pyrazole coupling. The composition of the products and their yields are strongly affected by the choice of NiX2·nH2O and a molar ratio between the reactants. The [Ni(PzH)2{NH![[double bond, length as m-dash]](https://www.rsc.org/images/entities/char_e001.gif)
C(NR2)Pz}2](X)2 ([1–5](X)2; R2 = Me2 1, Et2 2, C4H8 3, C5H10 4, C5H10O 5; X = NO3, OTf – in all combinations, and R2 = Me2 1 for X = Cl, Br) complexes (named here as bis-chelate complexes), featuring two chelated ligands derived from the cyanamide–pyrazole coupling, were obtained selectively from NiX2·nH2O when the molar ratio between the reactants NiX2 : PzH : NCNR2 was 1 : 4 : (2.3). By using NiX2·6H2O (X = ClO4, OTs) and with the molar ratio NiX2 : PzH : NCNR2 1 : 3 : (3.5), the pure tris-chelate species [Ni{NHC(NR2)Pz}3]X2 ([6–7](ClO4)2, R2 = C4H8 6, C5H10 7; [8](OTs)2, R2 = Me2) were isolated. Structurally similar complexes are not formed under the coupling conditions when conventional nitriles NCR (R = Alk; for instance, NCMe) were applied as the nitrile component of the reaction. Quantum-chemical calculations demonstrate that generation of the tris-chelate [Ni{NHC(NR2)Pz}3]2+ species is thermodynamically driven with the energetic difference 4.6 kcal mol−1 between appropriate bis- and tris-chelate products, while for conventional nitrile derivatives the bis-chelate products are thermodynamically more preferable. The structures of eight complexes, viz. [1](Cl)2, [1–2](NO3)2, [4](NO3)2, [1–2](OTf)2, [3](OTf)2·Me2CO, and [9](OTf)2 were established by single crystal X-ray diffraction.
中文翻译：
镍（II）介导的氰酰胺-吡唑偶联突出显示了NCNR2和NCR腈配体的独特反应性
吡唑（PzH），N，N-二取代氰酰胺NCNR 2（R 2 = Me 2，Et 2，C 4 H 8，C 5 H 10，C 5 H 10 O）和镍盐NiX 2之间的反应· n H 2 O（X = NO 3，OTf，ClO 4，Cl，OTs，n = 6； Br，n = 3）提供具有由Ni II衍生的配体的配合物介导的氰酰胺-吡唑偶联。NiX 2 · n H 2 O的选择和反应物之间的摩尔比极大地影响了产物的组成及其产率。[Ni（PzH）2 {NHC（NR 2）Pz} 2 ]（X）2（[ 1–5 ]（X）2； R 2 = Me 2 1，Et 2 2，C 4 H 8 3， C 5 H 10 4，C 5 H 10 O 5； X = NO 3，OTf –所有组合，对于X = Cl，Br ，R 2 = Me 2 1络合物（在此称为双螯合物），其特征是从NiX 2选择性地获得了两个衍生自氰胺-吡唑偶联的螯合配体· ñ ħ 2 O在反应物之间的摩尔比NIX 2 ：PZH：NCNR 2为1：4：（2.3）。通过使用NiX 2 ·6H 2 O（X = ClO 4，OTs），并使用摩尔比NiX 2 ：PzH：NCNR 2 1：3：（3.5），得到纯三螯合物[Ni {NH C（NR 2）Pz} 3 ] X分离出2（[ 6-7 ]（ClO 4） 2，R 2 = C 4 H 8 6，C 5 H 10 7； [ 8 ]（OTs） 2，R 2 = Me 2）。当使用常规腈NCR（R = Alk；例如NCMe）作为反应的腈组分时，在偶联条件下不会形成结构相似的配合物。量子化学计算表明，三螯合物[Ni {NHC（NR 2）Pz} 3 ] 2+的生成合适的双螯合物和三螯合物产物之间的能量差为4.6 kcal mol -1进行热力学驱动，而对于常规腈衍生物，双螯合物产物在热力学上更优选。八个复合物的结构，即。[ 1 ]（Cl）2，[ 1-2 ]（NO 3）2，[ 4 ]（NO 3）2，[ 1-2 ]（OTf）2，[ 3 ]（OTf）2 ·Me 2 CO，和[ 9 ]（OTf）2 通过单晶X射线衍射确定。
更新日期：2020-04-24
C(NR2)Pz}2](X)2 ([1–5](X)2; R2 = Me2 1, Et2 2, C4H8 3, C5H10 4, C5H10O 5; X = NO3, OTf – in all combinations, and R2 = Me2 1 for X = Cl, Br) complexes (named here as bis-chelate complexes), featuring two chelated ligands derived from the cyanamide–pyrazole coupling, were obtained selectively from NiX2·nH2O when the molar ratio between the reactants NiX2 : PzH : NCNR2 was 1 : 4 : (2.3). By using NiX2·6H2O (X = ClO4, OTs) and with the molar ratio NiX2 : PzH : NCNR2 1 : 3 : (3.5), the pure tris-chelate species [Ni{NHC(NR2)Pz}3]X2 ([6–7](ClO4)2, R2 = C4H8 6, C5H10 7; [8](OTs)2, R2 = Me2) were isolated. Structurally similar complexes are not formed under the coupling conditions when conventional nitriles NCR (R = Alk; for instance, NCMe) were applied as the nitrile component of the reaction. Quantum-chemical calculations demonstrate that generation of the tris-chelate [Ni{NHC(NR2)Pz}3]2+ species is thermodynamically driven with the energetic difference 4.6 kcal mol−1 between appropriate bis- and tris-chelate products, while for conventional nitrile derivatives the bis-chelate products are thermodynamically more preferable. The structures of eight complexes, viz. [1](Cl)2, [1–2](NO3)2, [4](NO3)2, [1–2](OTf)2, [3](OTf)2·Me2CO, and [9](OTf)2 were established by single crystal X-ray diffraction.
中文翻译：
镍（II）介导的氰酰胺-吡唑偶联突出显示了NCNR2和NCR腈配体的独特反应性
吡唑（PzH），N，N-二取代氰酰胺NCNR 2（R 2 = Me 2，Et 2，C 4 H 8，C 5 H 10，C 5 H 10 O）和镍盐NiX 2之间的反应· n H 2 O（X = NO 3，OTf，ClO 4，Cl，OTs，n = 6； Br，n = 3）提供具有由Ni II衍生的配体的配合物介导的氰酰胺-吡唑偶联。NiX 2 · n H 2 O的选择和反应物之间的摩尔比极大地影响了产物的组成及其产率。[Ni（PzH）2 {NH
C（NR 2）Pz} 2 ]（X）2（[ 1–5 ]（X）2； R 2 = Me 2 1，Et 2 2，C 4 H 8 3， C 5 H 10 4，C 5 H 10 O 5； X = NO 3，OTf –所有组合，对于X = Cl，Br ，R 2 = Me 2 1络合物（在此称为双螯合物），其特征是从NiX 2选择性地获得了两个衍生自氰胺-吡唑偶联的螯合配体· ñ ħ 2 O在反应物之间的摩尔比NIX 2 ：PZH：NCNR 2为1：4：（2.3）。通过使用NiX 2 ·6H 2 O（X = ClO 4，OTs），并使用摩尔比NiX 2 ：PzH：NCNR 2 1：3：（3.5），得到纯三螯合物[Ni {NH C（NR 2）Pz} 3 ] X分离出2（[ 6-7 ]（ClO 4） 2，R 2 = C 4 H 8 6，C 5 H 10 7； [ 8 ]（OTs） 2，R 2 = Me 2）。当使用常规腈NCR（R = Alk；例如NCMe）作为反应的腈组分时，在偶联条件下不会形成结构相似的配合物。量子化学计算表明，三螯合物[Ni {NHC（NR 2）Pz} 3 ] 2+的生成合适的双螯合物和三螯合物产物之间的能量差为4.6 kcal mol -1进行热力学驱动，而对于常规腈衍生物，双螯合物产物在热力学上更优选。八个复合物的结构，即。[ 1 ]（Cl）2，[ 1-2 ]（NO 3）2，[ 4 ]（NO 3）2，[ 1-2 ]（OTf）2，[ 3 ]（OTf）2 ·Me 2 CO，和[ 9 ]（OTf）2 通过单晶X射线衍射确定。
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