Synthesis and characterization of copper(II) complexes of nonfacially coordinating heteroscorpionate ligands (4-carboxyphenyl)bis(3,5-dimethylpyrazolyl)methane and (3-carboxyphenyl)bis(3,5-dimethylpyrazolyl)methane

Complexes of Cu(II) derived from two new nonfacially coordinating heteroscorpionate ligands, (4-carboxyphenyl)bis(3,5-dimethylpyrazolyl)methane (L4c) and (3-carboxyphenyl)bis(3,5-dimethylpyrazolyl)methane (L3c), have been synthesized and characterized by X-ray diffraction, ESI-MS, IR, and UV-vis spectroscopy, electrochemistry, and magnetic susceptibility. The use of these new complexes as building blocks for the construction of supramolecular architectures is discussed.     

Synthesis of copper(I) bis(3,5-dimethylpyrazolyl)methane olefin complexes and their reactivity towards carbon monoxide

The chemistry of bis(3,5-dimethylpyrazolyl)methane complexes of copper(I) has been investigated and a dinuclear copper(I) derivative of formula {Cu₂[μ-CH₂(3,5-Me₂Pz)₂]₂}(TfO)₂ [TfO = trifluoromethanesulphonate anion, ], characterized by an uncommon bridging coordination of the bis(pyrazolyl)methane ligands, has been isolated and characterized by X-ray diffraction methods. Moreover, new olefin derivatives of general formula [Cu[CH₂(3,5-Me₂Pz)₂](olefin)]TfO have been prepared (olefin: coe = cyclooctene, van = 4-vinylanisole, nbe = norbornene), their carbonylation reactions, {Cu[CH₂(3,5-Me₂Pz)₂](olefin)}TfO + CO ? {Cu[CH₂(3,5-Me₂Pz)₂](CO)}TfO + olefin, have been studied gas volumetrically and the thermodynamical parameters of the equilibria for the displacement of the coordinated olefin by carbon monoxide have been determined.     

Networks based on hydrogen-bonds containing phosphorus anions and tris(3,5-dimethylpyrazolyl)borate nickel(II) moieties

Five structural kinds of nickel hydrogen-bonded networks containing hydrotris(3,5-dimethylpyrazolyl)borate ligands (Tp^∗) have been elucidated by X-ray diffraction, [Tp^∗Ni(OH₂)₃][(p-NO₂C₆H₄O)₂PO₂] (4), [Tp^∗Ni(OH₂)₃][Me₂PO₂]·Me₂P(O)OH (5), [Tp^∗Ni(OH₂)₃][(nBuO)₂PO₂]·0.5H₂O (6), [(Hpz)Tp^∗Ni(OH₂)₂][(Ph)PO₂OH] (7) and [Tp^∗Ni(OH₂)₂(Me₂PO₂)] (8). The most relevant supramolecular feature of complexes 4-8 is all of them form coordination networks based on hydrogen bonds between water molecules and phosphate, phosphonate or phosphinate anions. These hydrogen bonds are formed within the monomer units in addition to connect monomers along the chains. Their behaviors in solution were investigated by one- and two-dimensional ¹H NMR techniques.     

Mono and dinuclear hydrotris(3,5-dimethylpyrazolyl)borato tantalum complexes

In an effort to obtain suitable starting materials, the synthesis and crystal structure of hydrotris(3,5-dimethylpyrazolyl)borato (Tp^Me2) tantalum(III) complexes are reported. Reaction of KTp^Me2 with [TaCl₂(tht)]₂(μ-Cl)₂(μ-tht) (1) (tht=tetrahydrothiophene) gives the X-ray characterized unsymmetrical (Tp^Me2Ta)(TaCl₃)(μ-Cl₂)(μ-tht) (2) in fair yield. This doubly bonded TaTa complex [2.6791(5) Å, diamagnetic, 18e per Ta] is a rare example of an unsymmetrical Ta₂X₆L₃ complex. The X-ray structure of Tp^Me2TaCl₂(PhCCMe) (3) is also reported. It has the (4e)-alkyne in the symmetry plane of the molecule. The trans effects of tht and phenylpropyne are discussed. 1 is inert towards the reaction with a second equivalent of KTp^Me2.     

A convenient synthetic route to half-sandwich rhodium(III) complexes of the tripodal ligand tris(3,5-dimethylpyrazolyl)methane

The synthesis of the complex [RhCl3tpm*], (1), (tpm*= tris(3,5-dimethylpyrazolyl)methane) is reported. This complex is a suitable starting material for the synthesis of heteroleptic half-sandwich complexes: it has been used to synthesise the complexes; [RhCl(bpy)tpm*][(PF6)2][2][(PF6)2](bpy = 2,2'-bipyridyl), [RhCl(phen)tpm*][(PF6)2][3][(PF6)2]. (phen = 1,10-phenanthroline), [RhCl2(py)tpm*][(PF6)], [4][(PF6)2], (py = pyridine), and[RhCl(py)2tpm*][(PF6)2], [5][(PF6)2]. The structures of [2][(PF6)2], [33][(PF6)2], [4][(PF6)2], and [5][(PF6)2] have been determined by X-ray crystallography. The electrochemical and photophysical properties of these new compounds have also been investigated.     

Coordination compounds derived from transition metal salts and bis(3,5-dimethylpyrazolyl)methane

Summary The preparation of transition metal complexes containing the sterically hindered ligand, bis(3,5-dimethylpyrazolyl)methane (LL) is described. Compounds of formula M(LL)X₂ (M = Co^II, Ni^II or Zn^II and X = Cl^– or Br^–) or M(LL)₂X₂ (M = Mn^II, Fe^II, Co^II, Ni^II, Cu^II, Zn^II or Cd^II and X = ClO ₄ ^– ; M = Co^II, Ni^II, Cu^II or Zn^II and X = NO ₃ ^– ; M = Ni^II or Cu^II and X = Cl^– or Br^–) have been isolated. In addition, an apparently trimeric Cu₃(LL)₄Cl₆ · EtOH compound is reported. For Ni(LL)Cl₂ a five-coordinated chloro-bridged dimer is found. The perchlorato compounds, M(LL)₂(ClO₄)₂, appear to have one bidentate ClO ₄ ^– and one ionic ClO ₄ ^– group. The M(LL)₂ species appears to occur either in octahedral geometry, leaving twocis-positions free, or in a tetrahedral geometry without space for other ligands, and probably also in a five-coordinate geometry with one free ligand position.Structural conclusions are drawn from i.r., far-i.r. and ligand-field spectra, x-ray powder patterns, magnetic susceptibility data, e.s.r. spectra and conductivity data.     

The co-ordination chemistry of tris(3,5-dimethylpyrazolyl)methane manganese carbonyl complexes: synthetic, electrochemical and DFT studies

The tricarbonyl [Mn(CO)(3){HC(pz')(3)}][PF(6)] 1(+)[PF(6)](-) (pz' = 3,5-dimethylpyrazolyl) reacts with a range of P-, N- and C-donor ligands, L, in the presence of trimethylamine oxide to give [Mn(CO)(2)L{HC(pz')(3)}](+) {L = PEt(3)3(+), P(OEt)(3)4(+), P(OCH(2))(3)CEt 5(+), py 6(+), MeCN 7(+), CNBu(t)8(+) and CNXyl 9(+)}. The complex [Mn(CO)(2)(PMe(3)){HC(pz')(3)}](+)2(+) is formed by reaction of 7(+) with PMe(3). Complexes 2(+) and 6(+) were structurally characterised by X-ray diffraction methods. Reaction of 7(+) with half a molar equivalent of 4,4'-bipyridine gives a purple compound assumed to be the bridged dimer [{HC(pz')(3)}Mn(CO)(2)(μ-4,4'-bipy)Mn(CO)(2){HC(pz')(3)}](2+)10(2+). The relative electron donating ability of HC(pz')(3) has been established by comparison with the cyclopentadienyl and tris(pyrazolyl)borate analogues. Cyclic voltammetry shows that each of the complexes undergoes an irreversible oxidation. The correlation between the average carbonyl stretching frequency and the oxidation potential for complexes of P- and C-donor ligands is coincident with the correlation observed for [Mn(CO)(3-m)L(m)(η-C(5)H(5-n)Me(n))]. The data for complexes of N-donor ligands, however, are not coincident due to the presence of a node (and phase change) between the metal and the N-donor in the HOMO of the complex as suggested by preliminary DFT calculations.     

Rhenium(I) carbonyl complexes derived from tris(3,5-dimethylpyrazolyl)borate ion

Treatment of [Re(CO)₄Cl]₂ with K[HB(3,5-Me₂C₃HN₂)₃] giving Re{HB(3,5-Me₂C₃HN₂)₃} (CO)₃ and Re(3,5-Me₂C₃HN₂)₂(CO)₃Cl, and bromination of the former to give Re{HB(3,5-Me₂-4-BrC₃N₂)₃}(CO)₃, without displacement of CO, is described.     

Synthesis, crystal structures and properties of the novel mononuclear copper(II) and tetranuclear cobalt(II) complexes with 3,6-bis-(3,5-dimethylpyrazolyl)-pyridazine

A novel monomer copper(II) complex [Cu(L)₂(SCN)] · ClO₄ (1) and a tetranuclear cobalt(II) complex [Co₄(L)₄(N₃)₄](OH)₄ · 2H₂O (2)(L = 3,6-bis-(3,5-dimethylpyrazolyl)-pyridazine) have been synthesized and structurally characterized. Single crystal X-ray analyses show that the Cu(II) atom is in a distorted trigonal bipyramidal coordinated environment consisting of four N atoms of L and one N atom of SCN⁻ in complex (1), and the monomer is extended to a 1D chain by the weak intermolecular π...π stacking interactions. In the complex (2), four Co(II) atoms are linked by four bridging azido groups in μ-1,1-N₃ (end-on) coordination mode to form a tetranuclear configuration. The fungicidal activity of the title compounds have been studied, and the results show that there are certain activities against several bacteria for the complexes and the ligand. Furthermore, two complexes exhibit blue emission fluoresce in the solid state at room temperature.     

Mono- and heteroligand iron(II) complexes with tris(3,5-dimethylpyrazol-1-yl)methane

Coordination compounds of iron(II) thiocyanate with tris(3,5-dimethylpyrazol-1-yl)methane (HC(3,5-Me₂Pz)₃), [Fe(HC(3,5-Me₂Pz)₃)₂](NCS)₂] (I) and [Fe(HC(3,5-Me₂Pz)₃)(Рhz)(NCS)₂] · H₂O (II), where Рhz is phthalazine, are synthesized. The complexes are studied by X-ray diffraction analysis, diffuse reflectance and IR spectroscopy, and static magnetic susceptibility measurements. The single crystals are obtained, and the molecular and crystal structures of complex II and compounds [Fe(HC(3,5-Me₂Pz)₃)(3,5-Me₂Pz)(NCS)₂] · С₂H₅OH (III), where 3,5-Me₂Pz is 3,5-dimethylpyrazole, and [Fe(HC(3,5-Me₂Pz)₃)₂][Fe(HC(3,5-Me₂Pz)₃)(NCS)₃]₂ (IV) are determined (CIF files CCDC 1415452 (II), 1415453 (III), and 1415454 (IV)). The study of the temperature dependence μ_eff(Т) in a range of 2–300 K shows exchange interactions of the antiferromagnetic character between the iron(II) ions in complexes I and II.     

Methylation of (2-methylethanethiol-bis-3,5-dimethylpyrazolyl)methane zinc complexes and coordination of the resulting thioether: relevance to zinc-containing alkyl transfer enzymes

A series of zinc complexes using a new tripodal, N(2)S, heteroscorpionate ligand (L3SH) that is isostructural and isoelectronic with the well-known N(3) trispyrazolylborates have been methylated in solution and the coordination properties of the resulting thioether examined. This system models the reactivity of zinc-containing enzymes involved in alkyl group transfers such as the DNA repair protein Ada from E. coli, or farnasyl transferase where it has been shown that the thioether resulting from alkyl group transfer remains in the coordination sphere of the zinc. The following complexes have been structurally characterized: [(L3S)ZnI] (1), [(L3SCH(3))ZnI(2)] (2), [(L3SCH(3))ZnI]BF(4) (3), [(L3SCH(3))Zn-mu-bis-acetato-mu-hydroxo-Zn(L3SCH(3))]BF(4) (5), [(L3SCH(3))ZnSPh(F5)]ClO(4) (7), and [(L3SCH(3))(2)Zn](BF(4))(2) (8). Complexes 3, 4, 5, 7, and 8 all display thioether coordination. Thus in the absence of superior anionic ligands, thioethers are reasonably good donors to zinc in either a tetrahedral or octahedral geometry. The methylation of the complex [(L3S)ZnSPh(F5)], which contains two different thiols, produces a single product, 7, where only the aliphatic thiol has been alkylated. This observation validates the suggestion that reactivity in enzymes with multiple zinc-bound thiols could be controlled by differences in thiol pK(a) (Hammes, B. S.; Warthen, C. R.; Crans, D.; Carrano, C. J. J. Biol. Inorg. Chem. 2000, 6, 82. Compound 7 is also of interest in that it resembles the metal ion-binding site of the blue copper protein, azurin.     

Crystal structures of copper(II) and nickel(II) complexes with 1,3-bis(3,5-di-tert-butylsalicylideneamino)propan-2-ol

Mononuclear copper(II) and nickel(II) complexes with 1,3-bis(3,5-di-tert-butylsalicylideneamino)propan-2-ol (H₃L) of the general formula [M(HL)] were obtained and structurally characterized. It was demonstrated that the presence of the tert-butyl groups precludes intermolecular hydrogen bonding in the crystals of the complexes and that their molecules are only linked by hydrophobic interactions.     

Allowed transitions and intercombination lines in B II

Systematic multiconfiguration results are reported for the 2s ^{2 1} S ₀ → 2s2p ³ P ₁ intercombination line in B II. Both Breit-Pauli and fully relativistic calculations have been performed. The two methods are compared and the results are found to be in good agreement. Length and velocity forms of the oscillator strengths of related allowed transitions are also reported. The latter are used as a check on accuracy along with term energy separation. Fine-structure splitting is also reported but shown not to be a check on accuracy in the Breit-Pauli approximation.     

Alkoxycarbene complexes of nickel(II)

Alkynylnickel complexes trans-C₆Cl₅Ni(PPhMe₂)₂CCR (IIIa, R  H; IIIb, R  Me; IIIc, R  Et; IIId, R  CH₂OH; IIIe, R  CH₂CH₂OH; IIIf, R  Ph; IIIg, R  C₆H₄OMe-p) have been prepared from trans-[C₆Cl₅Ni-(PPhMe₂)₂L]ClO₄ and monosubstituted acetylenes in the presence of triethylamine, and their reactions with alcohols in the presence of perchloric acid were studied. Complexes IIIa and IIIe afforded alkoxycarbene complexes trans-[C₆Cl₅Ni-(PPhMe₂)₂{C(OR′)Me}]ClO₄ (IVa, R′  Me; IVb, R′  Et; IVc, R′  n-Pr) or trans-C₆Cl₅Ni(PPhMe₂)₂{$\text{C(CH}{}_2\text{)}{}_3\text{O}$}]ClO₄(IVd), respectively, but IIIb either decomposed or afforded trans-C₆Cl₅Ni(PPhMe₂)₂CHC(OMe)Me, depending on the amount of acid used. Treatment of IVaIVd with amines resulted in deprotonation to give α-alkoxyvinyl complexes, trans-C₆Cl₅Ni(PPhMe₂)₂C(OR′)CH₂ (VIaVIc) or trans-C₆Cl₅Ni(PPhMe₂)₂$\text{CCHCH}{}_2\text{CH}{}_2\text{O}$ (VId), the reaction being reversible. A ¹H NMR study indicated: (i) that the carbene methyl and the vinyl protons IV or VI are D-exchangeable by MeOD without catalyst; (ii) that the basicity of VIa is comparable to those of amines; (iii) that the carbene complexes IVaIVc have two isomers due to hindered rotation about the C(carbene)O bond in solution, IVb existing in the Z-form in the solid state; (iv) that the rotationalbarriers (°G^≠) about the C(carbene)O bond in IVb and the NiC-(carbene) bond in IVd are 20 (or more) and 11.7 kcal/mol, respectively. These results are explained in term of double bond character of the carbene carbon and its surrounding atoms.     

Constructions of a set of novel hydrogen-bonded supramolecules from reactions of cobalt(II) salt with bis(3,5-dimethylpyrazolyl)methane and different carboxylic acids

Reactions of CoX₂·6H₂O (X = Cl⁻, ClO₄⁻) with bis(3,5-dimethylpyrazolyl)methane (dmpzm) and formic acid, acetic acid, benzoic acid, salicylic acid, maleic acid, or fumaric acid under the presence of KOH solution produced a new family of Co(II)/dmpzm complexes, [Co(dmpzm)₂L]X·nH₂O (1: L = O₂CH, X = Cl, n = 2; 2: L = OAc, X = Cl, n = 3; 3: L = benzoate, X = ClO₄, n = 1/3; 4: L = salicylate, X = ClO₄, n = 1/3) and [Co₂(dmpzm)₄L](ClO₄)₂·nSolv (5: L = maleate, n = 3, Solv = H₂O; 6: L = fumarate, n = 2, Solv = MeOH). These compounds were structurally characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Compounds 1–4 are mononuclear while 5–6 are binuclear. Each cobalt atom of 1–6 is hexacoordinate, with a distorted octahedral CoN₄O₂ coordination geometry incorporating two N,N′-bidentate dmpzm ligands and one O,O′-bidentate carboxylate ligand. There are rich intra- and intermolecular hydrogen bonds in the crystals of 1–6, thereby forming either 2D hydrogen-bonded networks (1 and 2) or 3D hydrogen-bonded networks (3–6). In addition, the thermal behaviors of 1–6 were also investigated.     

Cymantrenecarboxylate complexes of nickel(II) and cobalt(II)

Reactions of cymantrenecarboxylic acid (CO)₃MnC₅H₄COOH (CymCOOH) with Ni(II) and Co(II) pivalates in boiling THF followed by extraction of the products with diethyl ether or benzene and treatment with triphenylphosphine gave the binuclear complexes LM(CymCOO)₄ML (M = Ni (I) and Co (II); L = PPh₃). Treatment of the benzene extract of the intermediate cobalt cymantrenecarboxylate with 2,6-lutidine (L’) yielded the trinuclear complex L’Co(CymCOO)₃Co(CymCOO)₃CoL’ (III). Complex I is antiferromagnetic; μ_eff decreases from 3.7 to 0.9 μ_B in a temperature range from 300 to 2 K. Structures I-III were identified using X-ray diffraction. The frameworks of complexes I and II are like Chinese lanterns, having four carboxylate bridges and axial ligands L (Ni-P, 2.358(1) Å; Co-P, 2.412(2) Å). The metal atoms are not bonded to each other (Ni…Ni, 2.7583(9) Å; Co…Co, 2808 (2) Å). In complex III, either terminal Co atom is coordinated to one ligand L’ (Co-N, 2.059(2) Å). The Co atoms form a linear chain showing no M-M bonds (Co…Co, 3.346(1) Å), in which either terminal Co atom is linked with the central Co atom by three carboxylate bridges (on average, Co_centr-O, 2.164 Å; CO_term-O, 2.094 Å). In one of three carboxylate groups, only one carboxylate O atom serves as a bridge, while the other is bonded to the terminal Co atom only (Co_term-O, 2.094 and 2.389 Å); so this carboxylate group is a bridging and chelating ligand.     

Studies on nickel (II) complexes of some poly(1-pyrazolyl)alkane ligands

Summary The coordinating behaviour of tris(1-pyrazolyl)methane, HCpz₃ and 2,2-bis(1-pyrazolyl)propane, Me₂Cpz₂ ligands towards nickel(II) salts has been investigated. Tris(1-pyrazolyl)methane yields stable, solid complexes of the type [Ni(HCpz₃)X.H₂O].nH₂O (X=Cl, n=2; AcO, N=1) and [Ni(HCpz₃)₂]X₂ (X = Br, I, NO₃, or IO₄) whilst Me₂Cpz₂ ligand does not. However, Me₂Cpz₂ in the presence of poor coordinating polyanions such as BF ₄ ^– and PF ₆ ^– reacts readily to give stable complexes of the type [Ni(Me₂Cpz₂)₂X]Y (X=Cl, NO₃, or AcO and Y=BF₄ or PF₆). The complexes have been characterised by elemental analysis, magnetic moments, electronic and infrared absorption spectra. An octahedral structure has been proposed for the complexes [Ni(HCpz₃)X₂ · H₂O] · nH₂O with one water molecule occupying an axial position. An octahedral structure has also been proposed for the complex ions, [Ni(HCpz₃)₂]²⁺ and [Ni(Me₂Cpz₂)₂X]⁺(X = NO₃ or AcO) with the anion X acting as a bidentate ligand whilst [Ni(Me₂Cpz₂)₂Cl]⁺ is considered to have a square pyramidal structure.     

Square planar complexes of nickel(II), palladium(II) and platinum(II) with 1-(2-hydroxyphenyl)-3,5-diphenylformazan

Summary A novel series of formazan complexes of general formula FoML [H₂Fo = 1-(2-hydroxyphenyl)-3,5-diphenylformazan; M = Ni^II, Pd^II or Pt^II; L = NH₃, py and Ph₃P] are described. The formazan nickel(II) system shows linkage isomerism; one isomer, A, contains an unusual five-membered formazan chelate ring, whereas the other, isomer B, has the usual six-membered ring.¹³C n.m.r., u.v. and i.r. spectra are presented and interpreted. From these the palladium and platinum complexes appear to contain the six-membered ring of the B type isomer.     

The uranium-nitrogen bond in U IV complexes supported by the hydrotris(3,5-dimethylpyrazolyl)borate ligand

Insertion of benzonitrile and acetonitrile into the U-C bond of [U(Tp(Me2))Cl(2)(CH(2)SiMe(3))](Tp(Me2)= HB(3,5-Me(2)pz)(3)) gives the ketimide complexes [U(Tp(Me2))Cl(2){NC(R)(CH(2)SiMe(3))}](R = Ph (1); Me (2)). The identity of complex was ascertained by a single-crystal X-ray diffraction study. In the solid state exhibits octahedral geometry with a short U-N bond length to the ketimide ligand. We also report herein the synthesis and the X-ray crystal structures of the uranium amide complexes [U(Tp(Me2))Cl(2)(NR(2))](R = Et (3); Ph (4)). A detailed comparison of the U-N bond lengths in these compounds with other known U-N (and Th-N) distances in amide and ketimide actinide(IV) complexes is performed, confirming the short character of the U-N bond length in 1.