Acetate and acetamide complexes of [Ni(Me4[12]aneN4)]PF6: a tale of two ligands

Although there are many examples of acetate complexes, acetamide complexes are virtually unknown. A side‐by‐side comparison in (acetato‐κ²O,O′)(1,4,7,10‐tetramethyl‐1,4,7,10‐tetraazacyclododecane‐κ⁴N)nickel(II) hexafluoridophosphate, [Ni(C₂H₃O₂)(C₁₂H₂₈N₄)]PF₆, (1), and (acetamidato‐κ²O,O′)(1,4,7,10‐tetramethyl‐1,4,7,10‐tetraazacyclododecane‐κ⁴N)nickel(II) hexafluoridophosphate, [Ni(C₂H₄NO)(C₁₂H₂₈N₄)]PF₆, (2), shows the steric equivalence between these two ligands, suggesting that acetamide could be considered as a viable acetate replacement for electronic tuning.     

Komplexkatalyse: XXIII. Elektronenstoss-induzierter zerfall von η3-allylbromo(ligand)nickel(II)-komplexen C3H5NiBrL und einfluss der stärke der nickel—ligand-bindung auf die katalytische wirkung kationischer allylnickel(II)-komplexe [C3H5NiL2]PF6 für die 1,4-polymerisation des butadiens

The EI-mass spectra of nine η³-allyl bromo(ligand)nickel(II) complexes of the type C₃H₅NiBrL (L = monodentate neutral ligand) were recorded. The predominating fragmentation path is the reversed formation reaction leading to the ligand L and bis(η³-allylnickel(II) bromide), respectively. The relative strength of the NiL bond derived from the MS data is compared with the ligand's influence on the catalytic activity and selectivity of the corresponding η³-allylbis(ligand) complexes [C₃H₅NiL₂]PF₆ for the 1,4-polymerisation of 1,3-butadiene.     

[Bis­(di­phenyl­phosphino)­alkane](pentane‐2,4‐di­thionato) complexes of nickel(II)

The structures of a series of four‐coordinate nickel(II) complexes of the form [Ni(sacsac)L] PF₆ (sacsac = pentane‐2,4‐di­thione anion; L = (Ph₂P)₂(CH₂)_n, n = 1,2,3) have beendetermined. These are [bis­(di­phenyl­phosphino)­methane](pentane‐2,4‐di­thionato‐S,S′)­nickel(II) hexa­fluoro­phosphate, [Ni(C₂₅H₂₂P₂)(C₅H₇S₂)]PF₆, [1,2‐bis­(di­phenylphosphino)­ethane](pentane‐2,4‐di­thionato–S,S′)­nickel(II) hexa­fluoro­phosphate, [Ni(C₂₆H₂₄P₂)(C₅H₇S₂)]PF₆, and [1,3‐bis­(di­phenyl­phosphino)­propane](pentane‐2,4‐di­thionato‐S,S′)­nickel(II) hexa­fluoro­phosphate, [Ni(C₂₇H₂₆P₂)(C₅H₇S₂)]PF₆. All have a distorted square‐planar arrangement about Ni with angles around Ni varying with the length of the hydro­carbon chain.     

Nickel Tetracarbonyl as Starting Material for the Synthesis of NHC-stabilized Nickel(II) Allyl Complexes

A novel, useful in situ synthesis for NHC nickel allyl halide complexes [Ni(NHC)(η³-allyl)(X)] starting from [Ni(CO)₄], NHC and allyl halides is presented. The reaction of [Ni(CO)₄] with (i) one equivalent of the corresponding NHC and (ii) with an excess of the corresponding allyl chloride at room temperature leads with elimination of carbon monoxide to complexes of the type [Ni(NHC)(η³-allyl)(X)]. This approach was used to synthesize the complexes [Ni(tBu₂Im)(η³-H₂C -C (Me)-C H₂)(Cl)] ( 2 ), [Ni(iPr₂Im^Me)(η³-H₂C -C (Me)-C H₂)(Cl)] ( 3 ), [Ni(iPr₂Im)(η³-H₂C -C (Me)-C H₂)(Cl)] ( 4 ), [Ni(iPr₂Im)(η³-H₂C -C (H)-C (Me)₂)(Br)] ( 5 ), [Ni(Me₂Im^Me)(η³-H₂C -C (Me)-C H₂)(Cl)] ( 6 ), and [Ni(EtiPrIm^Me)(η³-H₂C -C (Me)-C H₂)(Cl)] ( 7 ). The complexes 1 to 7 were characterized using NMR and IR spectroscopy and elemental analysis, and the molecular structures are provided for 2 and 7 . The allyl nickel complexes 1 – 7 are stereochemically non-rigid in solution due to (i) NHC rotation about the nickel-carbon bond, (ii) allyl rotation about the Ni–η³-allyl axis and (iii) π–σ–π allyl isomerization processes. The allyl halide complexes can be methylated as was demonstrated by the methylation of a number of the complexes [Ni(NHC)(η³-allyl)(X)] with methylmagnesium chloride or methyllithium, which led to isolation of the complexes [Ni(Me₂Im)(η³-H₂C -C (Me)-C H₂)(Me)] ( 8 ), [Ni(tBu₂Im)(η³-H₂C -C (Me)-C H₂)(Me)] ( 9 ), [Ni(iPr₂Im^Me)(η³-H₂C -C (Me)-C H₂)(Me)] ( 10 ), [Ni(iPr₂Im)(η³-H₂C -C (Me)-C H₂)(Me)] ( 11 ), [Ni(iPr₂Im)(η³-H₂C -C (H)-C (Me)₂)(Me)] ( 12 ), and [Ni(EtiPrIm^Me)(η³-H₂C -C (Me)-C H₂)(Me)] ( 13 ). These complexes were fully characterized including X-ray molecular structures for 10 and 11 .     

Syndiotactic 1,2-polybutadiene with Co-CS2 catalyst system. IV. Mechanism of syndiotactic polymerization of butadiene with cobalt compounds–organoaluminum–CS2

A mechanism is proposed for the polymerization of syndiotactic 1,2-polybutadiene (s-PB) with soluble cobalt-organoaluminum-CS₂. The proposed active species have structures which consist of side-on coordination of CS₂ to cobalt, anti-π-allyl growing end, cisoid bidentate coordination of butadiene, and activation by complex formation with organoaluminum at the nonbonded sulfur of the coordinated CS₂. This proposal is based on findings for the aluminum-free catalyst Co(C₄H₆)(C₈H₁₃)-CS₂. It is tentatively interpreted that syndiotactic 1,2 polymerization proceeds under the influence of the side-on coordinated CS₂, by which the reactivity between the terminal carbons of butadiene and the C3 of the π-allyl end is enhanced.     

Benzylnickel(II)-Komplexe und ihre Reaktionen

Benzyl Nickel(II) Complexes and their Reactions By the oxydative addition of p-substituted benzyl chlorides to (Ph₃P)₂Ni(C₂H₄) at ?20°C the violet nickel(II) complexes (Ph₃P)₂Ni(p-CH₂C₆H₄R)Cl (R ? CN, COOH, CH₃, Cl) are, formed. In water containing solutions the carbonic acid (Ph₃P)₂Ni(p-CH₂C₆H₄COOH)Cl is rearranged to the corresponding p-methylbenzoate. With carbon dioxide the complexes (Ph₃P)₂Ni(p? CH₂C₆H₄R)Cl react like Grignard compounds. Diphenyl ethine and butadien-1,3 are inserted in the Ni—C bond at room temperature. Substituted nickel-σ-vinyl or π-allyl complexes are obtained. The reactivity of the nickel-σ-benzyl compounds is compared with that of other nickel(II)-alkyl compounds.     

Four NiII complexes with the new cyclam–methylimidazole ligand 1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane

Although it has not proved possible to crystallize the newly prepared cyclam–methylimidazole ligand 1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane (L^Im1), the trans and cis isomers of an Ni^II complex, namely trans‐aqua{1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}nickel(II) bis(perchlorate) monohydrate, [Ni(C₁₅H₃₀N₆)(H₂O)](ClO₄)₂·H₂O, (1), and cis‐aqua{1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}nickel(II) bis(perchlorate), [Ni(C₁₅H₃₀N₆)(H₂O)](ClO₄)₂, (2), have been prepared and structurally characterized. At different stages of the crystallization and thermal treatment from which (1) and (2) were obtained, a further two compounds were isolated in crystalline form and their structures also analysed, namely trans‐{1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}(perchlorato)nickel(II) perchlorate, [Ni(ClO₄)(C₁₅H₃₀N₆)]ClO₄, (3), and cis‐{1,8‐bis[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}nickel(II) bis(perchlorate) 0.24‐hydrate, [Ni(C₂₀H₃₆N₆)](ClO₄)₂·0.24H₂O, (4); the 1,8‐bis[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane ligand is a minor side product, probably formed in trace amounts in the synthesis of L^Im1. The configurations of the cyclam macrocycles in the complexes have been analysed and the structures are compared with analogues from the literature.     

Ni-Catalyzed Borylation of Aryl Sulfoxides

A nickel/N-heterocyclic carbene (NHC) catalytic system has been developed for the borylation of aryl sulfoxides with B₂(neop)₂ (neop=neopentyl glycolato). A wide range of aryl sulfoxides with different electronic and steric properties were converted into the corresponding arylboronic esters in good yields. The regioselective borylation of unsymmetric diaryl sulfoxides was also feasible leading to borylation of the sterically less encumbered aryl substituent. Competition experiments demonstrated that an electron-deficient aryl moiety reacts preferentially. The origin of the selectivity in the Ni-catalyzed borylation of electronically biased unsymmetrical diaryl sulfoxide lies in the oxidative addition step of the catalytic cycle, as oxidative addition of methoxyphenyl 4-(trifluoromethyl)phenyl sulfoxide to the Ni(0) complex occurs selectively to give the structurally characterized complex trans-[Ni(ICy)₂(4-CF₃-C₆H₄){(SO)-4-MeO-C₆H₄}] 4 . For complex 5 , the isomer trans-[Ni(ICy)₂(C₆H₅)(OSC₆H₅)] 5 - I was structurally characterized in which the phenyl sulfinyl ligand is bound via the oxygen atom to nickel. In solution, the complex trans-[Ni(ICy)₂(C₆H₅)(OSC₆H₅)] 5 - I is in equilibrium with the S-bonded isomer trans-[Ni(ICy)₂(C₆H₅)(SOC₆H₅)] 5 , as shown by NMR spectroscopy. DFT calculations reveal that these isomers are separated by a mere 0.3 kJ/mol (M06/def2-TZVP-level of theory) and connected via a transition state trans-[Ni(ICy)₂(C₆H₅)(η²-{SO}-C₆H₅)], which lies only 10.8 kcal/mol above 5 .     

A nitronyl nitro­xide complex of ­nickel(II) with nitrate as a ligand

The complex cation in [4,5-di­hydro-4,4,5,5-tetra­methyl-2-(2-pyridyl-κN)­imidazol-1-oxyl 3-oxide-κO³](nitrato-κ²O,O′)(N,N,N′,N′-tetra­methyl-1,2-ethanedi­am­ine-κ²N,N′)­nickel(II) hexafluorophosphate dichloromethane solvate, [Ni(NO₃)(C₆H₁₆N₂)(C₁₂H₁₆N₃O₂)]PF₆·CH₂Cl₂, is the first example of a nitro­nyl nitro­xide complex of a transition metal ion having d electrons in which nitrate is coordinated as a bidentate ligand. Owing to the smaller steric requirement of NO₃⁻, the Ni—­O(nitro­xide) bond length [2.014 (2) Å] is remarkably shorter than that in the corresponding ­β-­diketonate complexes [2.052 (4)–2.056 (2) Å].     

Crystal structure of a methyl(methoxy)carbene complex of nickel(II), trans-[Ni(C6Cl5)(PMe2Ph)2{C(OMe)Me}]BF4

The structure of a nickel(II) complex, trans-[Ni(C₆Cl₅)(PMe₂Ph)₂{C(OMe)Me}]BF₄, containing the simplest alkyl(alkoxy)carbene ligand has been determined by X-ray crystallography (R = 0.091). The geometry around the nickel atom is square-planar. The comparatively short NiC(1) bond length of 1.843(10) Å showed the presence of π-bonding in the nickel-carbene bond.     

Stacking of Benzene with Metal Chelates: Calculated CCSD(T)/CBS Interaction Energies and Potential‐Energy Curves

Accurate values for the energies of stacking interactions of nickel‐ and copper‐based six‐membered chelate rings with benzene are calculated at the CCSD(T)/CBS level. The results show that calculations made at the ωB97xD/def2‐TZVP level are in excellent agreement with CCSD(T)/CBS values. The energies of [Cu(C₃H₃O₂)(HCO₂)] and [Ni(C₃H₃O₂)(HCO₂)] chelates stacking with benzene are ?6.39 and ?4.77 kcal mol^?1, respectively. Understanding these interactions might be important for materials with properties that are dependent on stacking interactions.     

Komplexchemie reaktiver organischer verbindungen : XXXVII. Metallinduzierter abbau eines σ,π-koordinierten ketens in ein π-allyl/σ-aryl/π-olefin-system

Photolysis of diphenylketene in the presence of pentacarbonyliron yields the π-allyl/σ-acyl type compound [η³:η¹-(C₆H₅)₂CCO)Fe(CO)₃ (III) the molecular structure of which has been established by means of X-ray diffraction techniques. Metal-centered carboncarbon bond breaking and bond making in III is evident from ¹³CO labelling and crossover experiments. The dinuclear compound IV, structurally characterized by the π-allyl/σ-aryl/π-olefin hydrocarbon ligand CH(C₆H₄)C₆H₅, is formed upon irreversible decarbonylation of the ketene precursor III.     

Crystal structure and DFT analyses of a pentacoordinated PCP pincer nickel(II) complex

The reaction of NiCl₂ with 1,3‐bis[(diphenylphosphanyl)methyl]hexahydropyrimidine in the presence of 2,6‐dimethylphenyl isocyanide and KPF₆ afforded a new pentacoordinated PCP pincer Ni^II complex, namely {1,3‐bis[(diphenylphosphanyl)methyl]hexahydropyrimidin‐2‐yl‐κN²}(2,6‐dimethylphenyl isocyanide‐κC)nickel(II) hexafluoridophosphate 0.70‐hydrate, [Ni(C₉H₉N)(C₃₀H₃₀ClN₂P₂)]PF₆·0.7H₂O or [NiCl{C(NCH₂PPh₂)₂(CH₂)₃‐κ³P,C,P′}(Xylyl‐NC)]PF₆·0.7H₂O, in very good yield. Its X‐ray structure showed a distorted square‐pyramidal geometry and the compound does not undergo dissociation in solution, as shown by variable‐temperature NMR and UV–Vis studies. Density functional theory (DFT) calculations provided an insight into the bonding; the nickel dsp²‐hybridized orbitals form the basal plane and the nearly pure p orbital forms the axial bond. This is consistent with the NBO (natural bond orbital) analysis of analogous nickel(II) complexes.     

Synthesis of neutral and zwitterionic phosphinomethylpyrrolato complexes of nickel

Potassium salts of the new 2-phosphinomethyl-1H-pyrroles, K[R₂PCH₂C₄H₃N] (R = Ph, Cy) react with (η³-allyl)nickel bromide to give the chelate complexes (R₂PCH₂C₄H₃N)Ni(allyl), whereas the sterically hindered 2-diphenylphosphinomethyl-5-t-butyl-1H-pyrrole and (η³-allyl)nickel bromide afford a phosphine adduct (HNC₄H₂-5-Bu^t-2-CH₂PPh₂)Ni(allyl)Br which is stabilized by an intramolecular NHBr hydrogen bond. The addition of B(C₆F₅)₃ to (R₂PCH₂C₄H₃N)Ni(allyl) leads to an electrophilic attack in 5-position of the pyrrole ring, to give the thermally unstable zwitterions (η³-C₃H₅)Ni[NC₄H₃(2-CH₂PR₂)-5-B(C₆F₅)₃] which catalyse the isomerisation of 1-hexene. The addition of B(C₆F₅)₃ is reversible, and slow ligand rearrangement to Ni(N-P)₂ products appears to be the major catalyst deactivation pathway.     

Two nickel(II) bis[(pyridin‐2‐yl)methyl]amine complexes with homophthalic and benzene‐1,2,4,5‐tetracarboxylic acids

Two new Ni^II complexes involving the ancillary ligand bis[(pyridin‐2‐yl)methyl]amine (bpma) and two different carboxylate ligands, i.e. homophthalate [hph; systematic name: 2‐(2‐carboxylatophenyl)acetate] and benzene‐1,2,4,5‐tetracarboxylate (btc), namely catena‐poly[[aqua{bis[(pyridin‐2‐yl)methyl]amine‐κ³N,N′,N′′}nickel(II)]‐μ‐2‐(2‐carboxylatophenyl)aceteto‐κ²O:O′], [Ni(C₉H₆O₄)(C₁₂H₁₃N₃)(H₂O)]_n, and (μ‐benzene‐1,2,4,5‐tetracarboxylato‐κ⁴O¹,O²:O⁴,O⁵)bis(aqua{bis[(pyridin‐2‐yl)methyl]amine‐κ³N,N′,N′′}nickel(II)) bis(triaqua{bis[(pyridin‐2‐yl)methyl]amine‐κ³N,N′,N′′}nickel(II)) benzene‐1,2,4,5‐tetracarboxylate hexahydrate, [Ni₂(C₁₀H₂O₈)(C₁₂H₁₃N₃)₂(H₂O)₂]·[Ni(C₁₂H₁₃N₃)(H₂O)₃]₂(C₁₀H₂O₈)·6H₂O, (II), are presented. Compound (I) is a one‐dimensional polymer with hph acting as a bridging ligand and with the chains linked by weak C—H...O interactions. The structure of compound (II) is much more complex, with two independent Ni^II centres having different environments, one of them as part of centrosymmetric [Ni(bpma)(H₂O)]₂(btc) dinuclear complexes and the other in mononuclear [Ni(bpma)(H₂O)₃]²⁺ cations which (in a 2:1 ratio) provide charge balance for btc⁴⁻ anions. A profuse hydrogen‐bonding scheme, where both coordinated and crystal water molecules play a crucial role, provides the supramolecular linkage of the different groups.     

Heterobimetallic Nickel(II) Complexes of Ferrocenyldithiophosphonates. Molecular Structures of [{FcP(OR)S2}2Ni] [Fc = Fe(η5‐C5H4)(η5‐C5H5), R = Et,Pri, Bus,Bui]

The reaction of 2,4‐diferrocenyl‐1,3‐dithiadiphosphetane 2,4‐disulfide [FcPS(μ‐S)]₂ [Fc = Fe(η⁵‐C₅H₄)(η⁵‐C₅H₅)] with alcohols ROH gave the corresponding ferrocenyldithiophosphonic acids [FcPS(OR)(SH)], which were treated in situ with Ni(CH₃COO)₂·4H₂O in acetic acid to yield the square‐planar heterobimetallic trinuclear complexes [{FcP(OR)S₂}₂Ni] (R = Me ( 1 ), Et ( 2 ), Prⁱ ( 3 ), Bu^s ( 4 ) and Buⁱ ( 5 )). Compounds 1‐5 were characterized by elemental analysis, MS, NMR (¹H, ¹³C and ³¹P), IR spectroscopy, and 2‐5 also by X‐ray crystallography. Cyclovoltammetric studies on the heterobimetallic nickel(II) complexes 1‐5 showed irreversible reduction to unstable nickel(I) complexes and an irreversible two‐electron oxidation of the sulfur‐containing nickel fragments, followed by a reversible one‐electron oxidation of the two ferrocenyl groups.     

[(8a,9,9a‐η)‐9‐(η5‐Cyclopentadienyl)‐9‐nickelafluorenyl](η5‐pentamethylcyclopentadienyl)nickel(II)

The title compound, [Ni₂(C₅H₅)(C₁₀H₁₅)(C₁₂H₈)] or [Ni(C₁₀H₁₅){Ni(C₅H₅)(C₁₂H₈)}], is a rare example (and the first obtained from nickelafluorenyllithium) of an analogue of nickelocene in which the central Ni atom is coordinated to one pentamethylcyclopentadienyl ring and one nickelafluorenyl ring. Both rings lie almost parallel to one another: the dihedral angle between the planes which include these rings is 4.4 (1)°. Slip parameter analysis indicates that the bonding mode of the central Ni atom to the nickelacyclic ring is between η³ and η⁵. Two‐dimensional layers of molecules are formed by C—H...π interactions.     

Insight into the structures of [M(C5H4I)(CO)3] and [M2(C12H8)(CO)6] (M = Mn and Re) containing strong I...O and π(CO)–π(CO) interactions

The compounds tricarbonyl(η⁵‐1‐iodocyclopentadienyl)manganese(I), [Mn(C₅H₄I)(CO)₃], (I), and tricarbonyl(η⁵‐1‐iodocyclopentadienyl)rhenium(I), [Re(C₅H₄I)(CO)₃], (III), are isostructural and isomorphous. The compounds [μ‐1,2(η⁵)‐acetylenedicyclopentadienyl]bis[tricarbonylmanganese(I)] or bis(cymantrenyl)acetylene, [Mn₂(C₁₂H₈)(CO)₆], (II), and [μ‐1,2(η⁵)‐acetylenedicyclopentadienyl]bis[tricarbonylrhenium(I)], [Re₂(C₁₂H₈)(CO)₆], (IV), are isostructural and isomorphous, and their molecules display inversion symmetry about the mid‐point of the ligand C[triple‐bond]C bond, with the (CO)₃M(C₅H₄) (M = Mn and Re) moieties adopting a transoid conformation. The molecules in all four compounds form zigzag chains due to the formation of strong attractive I...O [in (I) and (III)] or π(CO)–π(CO) [in (I) and (IV)] interactions along the crystallographic b axis. The zigzag chains are bound to each other by weak intermolecular C—H...O hydrogen bonds for (I) and (III), while for (II) and (IV) the chains are bound to each other by a combination of weak C—H...O hydrogen bonds and π(Csp²)–π(Csp²) stacking interactions between pairs of molecules. The π(CO)–π(CO) contacts in (II) and (IV) between carbonyl groups of neighboring molecules, forming pairwise interactions in a sheared antiparallel dimer motif, are encountered in only 35% of all carbonyl interactions for transition metal–carbonyl compounds.     

[Ni(terpy)(H2O)]‐trans‐[Ni‐(μ‐CN)2‐(CN)2]n,a one‐dimensional linear tetra­cyano­nickelate chain

The one‐dimensional chain catena‐poly­[[aqua(2,2′:6′,2′′‐terpyridyl‐κ³N)­nickel(II)]‐μ‐cyano‐κ²N:C‐[bis­(cyano‐κC)nickelate(II)]‐μ‐cyano‐κ²C:N], [Ni(terpy)(H₂O)]‐trans‐[Ni‐μ‐(CN)₂‐(CN)₂]_n or [Ni₂­(CN)₄­(C₁₅H₁₁N₃)(H₂O)], consists of infinite linear chains along the crystallographic [10] direction. The chains are composed of two distinct types of nickel ions, paramagnetic octahedral [Ni(terpy)(H₂O)]²⁺ cations (with twofold crystallographic symmetry) and diamagnetic planar [Ni(CN)₄]^2? anions (with the Ni atom on an inversion center). The [Ni(CN)₄]^2? units act as bidentate ligands bridging through two trans cyano groups thus giving rise to a new example of a trans–trans chain among planar tetra­cyano­nickelate complexes. The coordination geometry of the planar nickel unit is typical of slightly distorted octahedral nickel(II) complexes, but for the [Ni(CN)₄]^2? units, the geometry deviates from a planar configuration due to steric interactions with the ter­pyridine ligands.     

Mononuclear nickel(II) and zinc(II) complexes with deprotonated forms of the tripodal hexadentate ligand 1,3‐bis(2‐hydroxybenzylidene)‐2‐(2‐hydroxybenzylideneaminomethyl)‐2‐methylpropane‐1,3‐diamine

In the crystal structures of both title compounds, [1,3‐bis(2‐hydroxybenzylidene)‐2‐methyl‐2‐(2‐oxidobenzylideneaminomethyl)propane‐1,3‐diamine]nickel(II) [2‐(2‐hydroxybenzylideneaminomethyl)‐2‐methyl‐1,3‐bis(2‐oxidobenzylidene)propane‐1,3‐diamine]nickel(II) chloride methanol disolvate, [Ni(C₂₆H_25.5N₃O₃)]₂Cl·2CH₄O, and [1,3‐bis(2‐hydroxybenzylidene)‐2‐methyl‐2‐(2‐oxidobenzylideneaminomethyl)propane‐1,3‐diamine]zinc(II) perchlorate [2‐(2‐hydroxybenzylideneaminomethyl)‐2‐methyl‐1,3‐bis(2‐oxidobenzylidene)propane‐1,3‐diamine]zinc(II) methanol trisolvate, [Zn(C₂₆H₂₅N₃O₃)]ClO₄·[Zn(C₂₆H₂₆N₃O₃)]·3CH₄O, the 3d metal ion is in an approximately octahedral environment composed of three facially coordinated imine N atoms and three phenol O atoms. The two mononuclear units are linked by three phenol–phenolate O—H...O hydrogen bonds to form a dimeric structure. In the Ni compound, the asymmetric unit consists of one mononuclear unit, one‐half of a chloride anion and a methanol solvent molecule. In the O—H...O hydrogen bonds, two H atoms are located near the centre of O...O and one H atom is disordered over two positions. The Ni^II compound is thus formulated as [Ni(H_1.5L)]₂Cl·2CH₃OH [H₃L is 1,3‐bis(2‐hydroxybenzylidene)‐2‐(2‐hydroxybenzylideneaminomethyl)‐2‐methylpropane‐1,3‐diamine]. In the analogous Zn^II compound, the asymmetric unit consists of two crystallographically independent mononuclear units, one perchlorate anion and three methanol solvent molecules. The mode of hydrogen bonding connecting the two mononuclear units is slightly different, and the formula can be written as [Zn(H₂L)]ClO₄·[Zn(HL)]·3CH₃OH. In both compounds, each mononuclear unit is chiral with either a Δ or a Λ configuration because of the screw coordination arrangement of the achiral tripodal ligand around the 3d metal ion. In the dimeric structure, molecules with Δ–Δ and Λ–Λ pairs co‐exist in the crystal structure to form a racemic crystal. A notable difference is observed between the M—O(phenol) and M—O(phenolate) bond lengths, the former being longer than the latter. In addition, as the ionic radius of the metal ion decreases, the M—O and M—N bond distances decrease.