Identification of Hexameric Water and Hybrid Water–Chloride Clusters Intercalated in the Crystal Hosts of (Imidoylamidine)nickel(II) Complexes

Abstract

Two structurally related bis(imidoylamidine or 1,3,5‐triazapentadiene)nickel(II) compounds {Ni[HN=C(3‐py)NC(3‐py)=NH]2}·H2O·MeOH (1) and [Ni{HN=C(3‐py)N(H)C(3‐py)=NH}2]Cl2 (2) with symmetrical 3‐pyridyl (3‐py) substituents have been prepared by direct 2‐butanone oxime mediated transformation of 3‐cyanopyridine in the presence of Ni(MeCO2)2·4H2O or NiCl2·2H2O, respectively. Compounds 1 and 2 have been characterized by elemental analyses, IR, 1H and 13C{1H} NMR spectroscopy, and FAB+ mass spectrometry, while their slow recrystallization in air from organic solvents revealed a high affinity for water and resulted in the formation of the derived compounds [Ni{HN=C(3‐py)NC(3‐py)=NH}2]·6H2O (1′) and [Ni{HN=C(3‐py)N(H)0.5C(3‐py)=NH}2]Cl·2H2O (2′). Single‐crystal X‐ray diffraction analyses allowed the identification of discrete hexameric water or hybrid water–chloride clusters hosted by the crystal matrixes of 1′ and 2′, respectively. Both the (H2O)6 and [(H2O)4(Cl)2]2– clusters possess similar geometries and consist of cyclic planar tetranuclear (H2O)4 or [(H2O)2(Cl)2]2– cores with two dangling water molecules. These water associates occupy voids in the crystal cells and display extensive H‐bonding interactions with monomeric nickel–organic units, thus playing a key role in the formation of 3D hydrogen‐bonded supramolecular assemblies. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

1,3,5‐Triazapentadiene Nickel(II) Complexes Derived from a Ketoxime‐Mediated Single‐Pot Transformation of Nitriles

“…[6,9a,10] The IR spectra of 1-7 show typical [4,10] [4,6,10] The elemental analyses are consistent with the proposed formulations, which are also supported by X-ray crystallography.…”

“…In this study, we have further extended the versatility of our previously described Ni II -ketoxime-mediated system [10] towards the single-pot transformations of various organonitriles, thus opening up an easy entry to a series of cationic and neutral bis(1,3,5-triazapentadiene/ato)nickel(II) complexes 1-7. The advantages of this synthetic procedure with respect to prior work [3e,3f,4,5d,5e] include the simplicity, commercial availability and relatively low cost of the chemicals involved, rather mild reaction conditions and high yields and selectivities.…”

“…[5,6] However, most of the synthetic routes to tap derivatives are characterized by one or several of the following limitations: they (i) involve complicated multistep processes, (ii) require harsh reaction conditions, (iii) use expensive, uncommon and/or difficult-to-operate sensitive chemicals, (iv) show limited versatility and (v) exhibit low yields and selectivities. [3e,3f,4,5d,5e] Within our general research line focused on metal-mediated transformations of nitriles, [8,9] we have reported a facile ketoxime-promoted route for symmetrical bis (1,3,5-triazapentadiene/ato) complexes of Ni II , [10] generated from a sin-terized by IR, 1 H and 13 C{ 1 H} NMR spectroscopy, FAB-MS(+) or ESI-MS(+), elemental analyses and single-crystal X-ray diffraction [for 7 and solvated mono-{1a·(Me 2 CO) 0.33 · (MeOH) 0.67 } and bis-deprotonated (2b·2Me 2 CO, 4b·CHCl 3 , 5b·Me 2 CO and 6b·MeOH) products, formed upon recrystallization of 1, 2, 4, 5 and 6, respectively]. The crystal structures of all compounds bear similar monomeric Ni(tap) 2 units with a nearly square-planar geometry.…”

PdII‐Promoted Single‐Pot Template Transformations of Benzonitriles, Cyanoguanidine and Sodium Dicyanamide with the Formation of Symmetrical and Asymmetrical (1,3,5‐Triazapentadienate)palladium(II) Complexes

“…[7,11,13,16,[29][30][31][32][33] It is noteworthy that reactions of aliphatic liquid nitriles, such as acetonitrile or propionitrile, in excess (also playing the role of solvent) with PdCl 2 and 4 equiv. of acetone oxime and 2-butanone oxime were attempted, but in all cases only oxime-palladium(II) complexes of the type [PdCl 2 (oxime) 2 ] were isolated.…”

“…[7,11,16] Initially, this procedure involved an Ni II metal center, and liquid nitriles in a high excess since they acted also as solvents, [7] but a route with solid nitriles (in particular, cyanopyridine) was developed with a liquid oxime used as a solvent, [11] and the synthetic procedure was extended to involve other metal centers (in particular, Pd II ). [16] This route is attractive due to its simplicity and the low cost of the reagents, further it does not need special precautions and proceeds in air and in solvents and reagents that have not been predried.…”