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The facile syntheses and the structures of five new Cu(I) alkynyl clusters, [Cu(12)(hfac)(8)(C[triple chemical bond]CnPr)(4)(thf)(6)]xTHF (1), [Cu(12)(hfac)(8)(C[triple chemical bond]CtBu)(4)] (2), [Cu(12)(hfac)(8)(C[triple chemical bond]CSiMe(3))(4)] (3), [Cu(10)(hfac)(6)(C[triple chemical bond]CtBu)(4)(diethyl ether)]/[Cu(10)(hfac)(6)(C[triple chemical bond]CtBu)(3)(C[triple chemical bond]CnPr)(diethyl ether)] (4) and [Cu(10)(hfac)(6)(C[triple chemical bond]CtBu)(4)(diethyl ether)] (5) are reported, in which hfacH=1,1,1,5,5,5-hexafluoropentan-2,4-dione. The first independent molecule found in the crystals of 4 (4 a) proved to be chemically identical to 5. The Cu(10) and Cu(12) cores in these clusters are based on a central "square" Cu(4)C(4) unit. Whilst the connectivities of the Cu(10) or Cu(12) units remain identical the geometries vary considerably and depend on the bulk of the alkynyl group, weak coordination of ether molecules to copper atoms in the core and CuO intramolecular contacts formed between Cu-hfac units on the periphery of the cluster. Similar intermolecular contacts and interlocking of Cu-hfac units are formed in the simple model complex [Cu(2)(hfac)(2)(HC[triple chemical bond]CtBu)] (6). When linear alkynes, C(n)H(2n+1)C[triple chemical bond]CH, are used in the synthesis and non-coordinating solvents are used in the workup, further association of the Cu(4)C(4) cores occurs and clusters with more than eighteen copper atoms are isolated.

By employment of monoanionic hfac(1,1,1,5,5,5-hexafluoroacetylacetonate) as a “capping ligand”, it is possible to modulate the facile accretion of [{Cu(C⋮CR)}n] moieties to yield discrete high-nucl...

Two novel high nuclearity copper(I) alkynyl complexes, [Cu16(hfac)8(CCBut)8] (1) and [Cu20(hfac)8(CCCH2Ph)12] (2), that consist of complicated alkynyl bridged Cu(I) cores ‘capped’ by peripheral hfac ligands have been synthesised and characterised by X-ray structure determination. The photoluminescent properties of 1 and 2 together with the clusters, [Cu18(hfac)10(CCBun)8] (4) and [Cu26(hfac)11(CCPrn)15] (5) and the monomeric species, [Cu(hfac)(HCCCH2OMe)] (3), [Cu(hfac)(Me3SiCCSiMe3)] (6) and [Cu(hfac)(COD)] (7) are reported. A comparison of the photoluminescent spectra of the high nuclearity species with the related monomeric complexes have shown that the cluster luminescence is derived from transitions within the delocalised Cu-hfac chelate ring.

The synthesis and characterization of the Fe(III) and Co(II/III) complexes of tridentate heteroscorpionate ligands, (2-hydroxyphenyl) bis(pyrazolyl)methane, L1, and its derivatives, L2 and L3 are reported. Complexes prepared include [Fe(L)2][ClO4] where L=1–3, [Co(L3)2], [Co(L3)2][BPh4], and [Co(L)2]2Ag(MeCN)[BF4]3 where L=1 and 2. X-ray crystallographic analysis of several of the complexes have been completed. Electrochemical and other methods show that there is an oxidation state and ligand dependant cis/trans isomerization in these complexes.

The synthesis of a trinuclear thiolate bridged NiII system, [Ni3(L5S)4]2+ [L5SH = (2-sulfanylphenyl)bis(pyrazolyl)methane] which contains a linear NiS2NiS2Ni moiety, is reported. Two octahedrally coordinated (L5S)2Ni complexes, in which the thiol sulfurs are mutually cis, constitute the two terminal positions while the central position contains a distorted tetrahedral, four-coordinate, Ni(II) ion. In the presence of alkyl- or aryl-nitriles, such as MeCN, the [Ni3(L5S)4]2+ cation undergoes cleavage and rearrangement reactions to give thiolate bridged dinuclear dications, either [Ni2(L5S)2(MeCN)4]2+ or [Ni2(L5S)2(MeCN)2(H2O)2]2+, in which MeCN ligand N-donors (and/or H2O O-donors) occupy the vacant coordination sites of each Ni2+ atom. An analogous Co(II) dimer is also reported. The trimer → dimer reaction can be reversed by desolvation of [Ni2(L5S)2(MeCN)4]2+ or [Ni2(L5S)2(MeCN)2(H2O)2]2+ by an appropriate non-nitrile solvent, such as MeNO2 resulting in reformation of the [Ni3(L5S)4]2+ cation. Variable temperature magnetic data indicate that the Ni atoms in the trimer are weakly antiferromagnetically coupled while they are weakly ferromagnetically coupled in the dimer.

From the tridentate, mixed functionality ligands, bis(pyrazol-1-yl)methane(phen-2′-ol) (L1OH), bis(3,5-dimethylpyrazol-1-yl)methane(phen-2′-ol) (L2OH), and bis(3-isopropylpyrazol-1-yl)methane(phen-2′-ol) (L3OH), the following Cu(II) complexes have been synthesized, Cu(L1OH)2(solvent)BF42·H2O (1·H2O), Cu(L2OH)(L2O)BF4·H2O (2·H2O), Cu(L2O)2·MeCN·H2O (3·MeCN·H2O), and Cu2(μ-L3O)(L3OH)(μ-OH)(H2O)BF42·0.5CH2Cl2 (4·0.5CH2Cl2). 1, 2 and 4 have been characterized by X-ray crystallography, giving the following structural parameters: 1(MeCN)·MeCN, C30H28N10B2Cu1F8O2, monoclinic, a = 16.581(3); b = 12.041(2); c = 18.111(3) A; β = 103.102(8)°, V = 3521.0(10) A3, space group P21/c, Z=4.2·H2O, C34H39N8B1Cu1F4O3, monoclinic, a=9.513(2); b=26.808(3); c=14.148(5) A; β=90.39(2)°, V=3608.1(12) A3, space group P21/c, Z=4. 4·2(CH3)2CO, C45H49N8B2Cu2F8O5, monoclinic, a = 10.934(3); b = 21.701(5); c = 22.646(6) A; β = 96.77(3)°, V = 5336.0(20) A3, space group P21/c, Z=4.

The synthesis and characterization of the tridentate “heteroscorpionate” mixed functionality ligand, (2-thiophenyl)bis(pyrazolyl)methane, L1, is reported. This ligand was used to synthesize the complexes, [Fe(L1)2][ClO4], [Co(L1)2][BPh4], and [V(L1)2][BPh4]. X-ray crystallographic analysis of the latter two complexes gave the following structural parameters: [V(L1)2][BPh4]·MeCN·iPr2O, C58H57N9B1O1S2V1, monoclinic, a = 16.197(2) A, b = 19.281(2) A, c = 17.985(2) A, β = 102.343(9)°, space group P21/c; [Co(L1)2][BPh4]·CH2Cl2, C51H42N8B1Cl2Co1S2, triclinic, a = 12.751(1) A, b = 12.830(1) A, c = 14.740(1) A, α = 98.351(7)°, β = 98.122(6)°, γ = 97.023(8)°, space group P1. An example of the use of this new class of “heteroscorpionate” ligands for systematic comparisons of electronic properties of metal complexes with identical topology that vary only in the nature of one of the donor atoms is given.

The mixed functionality pyrazole/phenol ligand (2-hydroxyphenyl)bis(pyrazolyl)methane, L1OH, has been used to prepare a series of linear trimetallic systems with the general structural motif [M3(L1...

1H NMR spectra on the paramagnetic CoII and NiII, ML2 “sandwich” complexes of the “heteroscorpionate” ligands (2-hydroxyphenyl)bis (pyrazolyl)methane and its derivatives revealed the presence of isomeric, cis ↔ trans equilibria of these complexes in solution. The presence of some of the cis isomer in solution at equilibrium has been exploited to synthesize new heterometallic trinuclear species of the type [M1(L1O)2M2(L1O)2M1][BF4], where M1 (octahedral) and M2 (tetrahedral) are Zn2+, Cu2+, Ni2+, and Co2+. Rearrangements during the synthesis of some of these heterometallic species provided an interesting experimental confirmation of the site preferences (octahedral vs tetrahedral) for the first-row transition metals as predicted on the basis of crystal field stabilization energies. X-ray crystallographic characterization of many of the complexes reported in this study gives the following structural parameters: [Co2(L2O)2Cl2]·MeCN, C36H41N9Cl2Co2O2, monoclinic, a = 10.742(1) A, b = 21.387(2) A, c = 16.890(...

The preparation of a new class of mixed functionality biomimetic ligand, (2-hydroxyphenyl)bis(pyrazolyl)methane, L1, (2-hydroxyphenyl)bis(3,5-dimethylpyrazolyl)methane, L2, and (2-hydroxyphenyl)bis(3-isopropylpyrazolyl)methane, L3, is described. These ligands were used to synthesize the nickel(II) complexes, [Ni(L1)2], 1·MeCN; [Ni(L2)2], 2·0.5MeOH and 2·2H2O; [Ni(μ-L2)2NiCl2], 3·2H2O and 3·2CH2Cl2; [Ni3(μ3-Cl)2(μ-L3)2(L3)(MeOH)]Cl, 4·MeOH·4H2O and 4·MeOH·1.42iPr2O; and [Ni3(μ3-OH)2(μ-L3)3][BF4], 5 and 5·2Me2CO. X-ray crystal analysis of 1−5 gave the following structural parameters: 1·MeCN, C28H25N9NiO2, triclinic, a = 10.600(3) A, b = 11.371(3) A, c = 12.194(3) A, α = 71.17(2)°, β = 94.69(2)°, γ = 83.04(2)°, space group P1, Z = 2; 2·2H2O, C34H42N8NiO4, monoclinic, a = 9.037(2) A, b = 19.272(3) A, c = 19.643(3) A, β = 94.69(2)°, space group C2/c, Z = 4; 3·2CH2Cl2, C36H42N8Cl6Ni2O2, monoclinic, a = 13.891(4) A, b = 18.188(7) A, c = 15.012(4) A, β = 92.70(2)°, space group C2/c, Z = 4; 4·MeOH·1.42iPr2O, C67...

The syntheses of a new class of potentially biomimetic, tripodal, mixed functionality ligands, (2-hydroxyphenyl)bis(pyrazolyl)methane (L1), (2-hydroxyphenyl)bis(3,5-dimethylpyrazolyl)methane (L2), and (2-hydroxyphenyl)bis(3-isopropylpyrazolyl)methane (L3), are described. These ligands have been used to prepare the cobalt(II) complexes [Co(L1)2]·2.5MeOH·1.5H2O, 1·2.5MeOH·1.5H2O; [Co(L2)2]·0.5H2O, 2·0.5H2O; [Co(L3)Cl2], 3; and [Co3(μ3-OH)2(μ-L3)2(L3)(H2O)]BF4, 4. X-ray structural analysis of 1−4 gave the following structural parameters: 1, C30H34N8CoO6, triclinic, a = 8.286(2) A, b = 10.053(3) A, c = 10.562(2) A, α = 109.66(2)°, β = 96.57(1)°, γ = 91.11(3)°, space group P1, Z = 1; 2, C38H38N8CoO6, triclinic, a = 8.746(5) A, b = 10.900(5) A, c = 11.399(8) A, α = 70.82(4)°, β = 75.13(5)°, γ = 81.46(4)°, space group P1, Z = 1; 3, C20H26N4Cl4CoO, monoclinic, a = 10.934(2) A, b = 12.404(2) A, c = 19.267(3) A, β = 98.33(1)°, space group P21/n, Z = 4; 4, C58H70N12BCo3F4O9, monoclinic, a = 14.798(5) A, b = 23.65...

The crystal structure of N-methyl­methanesulfon­amide, C2H7NO2S, which is liquid under ambient conditions, has been determined at low temperature. Both the methyl group and H atom bonded to the amide N atom are in a gauche conformation with respect to the sulfonyl methyl group; the C—N—S—C and H—N—S—C torsion angles are −65.57 (20) and 71 (2)°, respectively. This finding is in contrast to previously published ab initio calculations for this mol­ecule.

The facile syntheses and the structures of five new Cu(I) alkynyl clusters, [Cu(12)(hfac)(8)(C[triple chemical bond]CnPr)(4)(thf)(6)]xTHF (1), [Cu(12)(hfac)(8)(C[triple chemical bond]CtBu)(4)] (2), [Cu(12)(hfac)(8)(C[triple chemical bond]CSiMe(3))(4)] (3), [Cu(10)(hfac)(6)(C[triple chemical bond]CtBu)(4)(diethyl ether)]/[Cu(10)(hfac)(6)(C[triple chemical bond]CtBu)(3)(C[triple chemical bond]CnPr)(diethyl ether)] (4) and [Cu(10)(hfac)(6)(C[triple chemical bond]CtBu)(4)(diethyl ether)] (5) are reported, in which hfacH=1,1,1,5,5,5-hexafluoropentan-2,4-dione. The first independent molecule found in the crystals of 4 (4 a) proved to be chemically identical to 5. The Cu(10) and Cu(12) cores in these clusters are based on a central "square" Cu(4)C(4) unit. Whilst the connectivities of the Cu(10) or Cu(12) units remain identical the geometries vary considerably and depend on the bulk of the alkynyl group, weak coordination of ether molecules to copper atoms in the core and CuO intramolecular contacts formed between Cu-hfac units on the periphery of the cluster. Similar intermolecular contacts and interlocking of Cu-hfac units are formed in the simple model complex [Cu(2)(hfac)(2)(HC[triple chemical bond]CtBu)] (6). When linear alkynes, C(n)H(2n+1)C[triple chemical bond]CH, are used in the synthesis and non-coordinating solvents are used in the workup, further association of the Cu(4)C(4) cores occurs and clusters with more than eighteen copper atoms are isolated.

The mixed functionality pyrazole/phenol ligand (2-hydroxyphenyl)bis(pyrazolyl)methane, L1OH, has been used to prepare a series of linear trimetallic systems with the general structural motif [M(3)(L1O)(4)](2+), where M = Mn(2+), Co(2+), Ni(2+), Cu(2+), and Zn(2+). Each of these complexes has been structurally characterized by X-ray crystallography giving the following structural parameters: [Zn(3)(L1O)(4)][BF(4)](2).H(2)O, C(52)H(44)N(16)B(2)F(8)O(5)Zn(3), monoclinic, a = 18.572(4) Å, b = 22.400(5) Å, c = 15.921(3), beta = 112.439(8) degrees, space group C2/c, Z = 4; [Cu(3)(L1O)(4)] [BF(4)](2).2MeCN, C(56)H(44)N(18)B(2)Cu(3)F(8)O(4), monoclinic, a = 40.574(2) Å, b = 16.701(1) Å, c = 19.841(2) Å, beta = 111.388(5) degrees, space group C2/c, Z = 8; [Ni(3)(L1O)(4)][ClO(4)](2).MeCN.0.5H(2)O, C(54)H(44)N(17)Cl(2)Ni(3)O(12.5), monoclinic, a = 12.324(4) Å, b = 26.537(2) Å, c = 18.829(3) Å, beta = 102.78(1) degrees, space group C2/c, Z = 4; [Co(3)(L1O)(4)][BF(4)](2).MeCN, C(54)H(44)N(17)B(2)Co(3)F(8)O(4), monoclinic, a = 12.395(2) Å, b = 26.483(3) Å, c = 18.703(4) Å, beta = 103.22(2) degrees, space group C2/c, Z = 4; [Mn(3)(L1O)(4)(MeCN)][ClO(4)](2).1.4MeCN, C(56.68)H(44)N(18.34)Cl(2)Mn(3)O(12), orthorhombic, a = 15.471(2) Å, b = 17.364(2) Å, c = 24.216(2) Å, space group Pbcn, Z = 4. For Zn(2+), Cu(2+), Ni(2+), and Co(2+) the central metal atom of the linear trimetallic [M(3)(L1O)(4)](2+) unit is four coordinate and has a pseudotetrahedral geometry with a dihedral angle, omega, between the two M(central)O(2)M(terminal) planes of 79.9 degrees (Zn), 61.2 degrees (Co), 60.4 degrees (Ni), and 46.8 degrees (Cu). The central Mn(2+) atom of [Mn(3)(L1O)(4)(MeCN)][ClO(4)](2).1.4MeCN is five-coordinate, with a trigonal bipyramidal stereochemistry, the result of an equatorially coordinated MeCN solvent molecule. Variable-temperature magnetic data indicate that the Ni, Cu, and Mn complexes display modest antiferromagnetic coupling between the metal centers, while the Co derivative is strongly ferromagnetically coupled.

The synthesis, crystallography and solution luminescence properties of [Cu18(hfac)10(CCC4Hn9)8] are reported.

Five new sterically hindered bis(imidazole) proligands have been synthesised: 1,2-bis(1-ethyl-4-phenylimidazol-2-yl)ethane (L1), bis(1-ethyl-4-phenylimidazol-2-yl)-(L2) and bis(1-methyl-4-phenylimidazol-2-yl)-dimethyl methane (L3), α, α′-bis(4,5′-diphenylimidazol-1-yl)-o-(L4) and m-xylene (L5). They have been characterised analytically and spectroscopically (1H NMR and mass) and L1 and L2 have been crystallised and characterised by X-ray crystallography. Complexation reactions were attempted with Cu(BF4)2·4.5H2O but only L1 formed a simple monomeric complex, [CuL12][BF4]2. The CuII is co-ordinated by four nitrogen atoms, Cu–Nav 2.01 A, in an essentially square-planar environment. The X-band EPR spectrum of solid [CuL12][BF4]2(g⊥≈1.967, g∥≈2.214, A∥≈196 × 10–4 cm–1) is consistent with a tetragonal ligand field but the Q-band spectrum of a frozen solution of the complex in CH2Cl2–toluene (10 : 1) at 77 K indicates a small rhombic distortion (gx≈2.034, gy≈2.052 and gz≈2.229, Az≈198 × 10–4 cm–1). In CH2Cl2 the complex displays a quasi-reversible CuII–CuI couple with an oxidation peak at +0.74 V and a coupled reduction at –0.07 V (scan rate of 0.2 V s–1). The complexes [CuL42][BF4]2·H2O and [CuL52][BF4]2·H2O appear to be polymeric with bridging ligands. Compound L3 reacted with Cu(BF4)2·4.5H2O to form [H2L3][BF4]2 which has been characterised by X-ray crystallography; L2 reacts similarly.