Orthopalladation of iminophosphoranes: synthesis, structure and study of stability

The reaction of Pd(OAc)(2) with polyfunctional iminophosphoranes Ph(3)P=NCH(2)CO(2)Me (1a), Ph(3)P=NCH(2)C(O)NMe(2) (1b), Ph(3)P=NCH(2)CH(2)SMe (1c) and Ph(3)P=NCH(2)-2-NC(5)H(4) (1d), gives the orthopalladated dinuclear complex [Pd(mu-Cl){C(6)H(4)(PPh(2)=NCH(2)CO(2)Me-kappa-C,N)-2}](2) (2a) and the mononuclear derivatives [PdCl{C(6)H(4)(PPh(2)=NCH(2)CONMe(2)-kappa-C,N,O)-2}] (2b), [PdCl{C(6)H(4)(PPh(2)=NCH(2)CH(2)SMe-kappa-C,N,S)-2}] (2c) and [PdCl{C(6)H(4)(PPh(2)=NCH(2)-2-NC(5)H(4)-kappa-C,N,N)-2}] (2d). The reaction implies the activation of a C-H bond in a phenyl ring of the phosphonium group, this fact being worthy of note due to the strongly deactivating nature of the phosphonium unit. The palladacycle containing the metallated carbon atom is remarkably stable toward the coordination of incoming ligands, while that formed by the iminic N atom and another heteroatom (O, 2a and 2b; S, 2c; N, 2d) is less stable and the resulting complexes can be considered as hemilabile. The X-ray crystal structures of the cyclopalladated [Pd(mu-Cl){C(6)H(4)(PPh(2)=NCH(2)CO(2)Me-kappa-C,N)-2}](2) (2a), [PdCl{C(6)H(4)(PPh(2)=NCH(2)-2-NC(5)H(4)-kappa-C,N,N)-2}] (2d), [Pd{C(6)H(4)(PPh(2)=NCH(2)CONMe(2)-kappa-C,N,O)-2}(NCMe)](ClO(4)) (7b) and [Pd{C(6)H(4)(PPh(2)NCH(2)CONMe(2)-kappa-C,N,O)-2}(py)](ClO(4)) (3b), and the coordination compound cis-[Pd(Cl)(2)(Ph(3)P=NCH(2)CH(2)SMe-kappa-N,S)] (8) are also reported.     

First row divalent transition metal complexes of aryl-appended tris((pyridyl)methyl)amine ligands: syntheses, structures, electrochemistry, and hydroxamate binding properties

Divalent manganese, cobalt, nickel, and zinc complexes of 6-Ph(2)TPA (N,N-bis((6-phenyl-2-pyridyl)methyl)-N-((2-pyridyl)methyl)amine; [(6-Ph(2)TPA)Mn(CH(3)OH)(3)](ClO(4))(2) (1), [(6-Ph(2)TPA)Co(CH(3)CN)](ClO(4))(2) (2), [(6-Ph(2)TPA)Ni(CH(3)CN)(CH(3)OH)](ClO(4))(2) (3), [(6-Ph(2)TPA)Zn(CH(3)CN)](ClO(4))(2) (4)) and 6-(Me(2)Ph)(2)TPA (N,N-bis((6-(3,5-dimethyl)phenyl-2-pyridyl)methyl)-N-((2-pyridyl)methyl)amine; [(6-(Me(2)Ph)(2)TPA)Ni(CH(3)CN)(2)](ClO(4))(2) (5) and [(6-(Me(2)Ph)(2)TPA)Zn(CH(3)CN)](ClO(4))(2) (6)) have been prepared and characterized. X-ray crystallographic characterization of 1A.CH(3)()OH and 1B.2CH(3)()OH (differing solvates of 1), 2.2CH(3)()CN, 3.CH(3)()OH, 4.2CH(3)()CN, and 6.2.5CH(3)()CN revealed mononuclear cations with one to three coordinated solvent molecules. In 1A.CH(3)()OH and 1B.2CH(3)()OH, one phenyl-substituted pyridyl arm is not coordinated and forms a secondary hydrogen-bonding interaction with a manganese bound methanol molecule. In 2.2CH(3)()CN, 3.CH(3)()OH, 4.2CH(3)()CN, and 6.2.5CH(3)()CN, all pyridyl donors of the 6-Ph(2)TPA and 6-(Me(2)Ph)(2)TPA ligands are coordinated to the divalent metal center. In the cobalt, nickel, and zinc derivatives, CH/pi interactions are found between a bound acetonitrile molecule and the aryl appendages of the 6-Ph(2)TPA and 6-(Me(2)Ph)(2)TPA ligands. (1)H NMR spectra of 4 and 6 in CD(3)NO(2) solution indicate the presence of CH/pi interactions, as an upfield-shifted methyl resonance for a bound acetonitrile molecule is present. Examination of the cyclic voltammetry of 1-3 and 5 revealed no oxidative (M(II)/M(III)) couples. Admixture of equimolar amounts of 6-Ph(2)TPA, M(ClO(4))(2).6H(2)O, and Me(4)NOH.5H(2)O, followed by the addition of an equimolar amount of acetohydroxamic acid, yielded the acetohydroxamate complexes [((6-Ph(2)TPA)Mn)(2)(micro-ONHC(O)CH(3))(2)](ClO(4))(2) (8), [(6-Ph(2)TPA)Co(ONHC(O)CH(3))](ClO(4))(2) (9), [(6-Ph(2)TPA)Ni(ONHC(O)CH(3))](ClO(4))(2) (10), and [(6-Ph(2)TPA)Zn(ONHC(O)CH(3))](ClO(4))(2) (11), all of which were characterized by X-ray crystallography. The Mn(II) complex 8.0.75CH(3)()CN.0.75Et(2)()O exhibits a dinuclear structure with bridging hydroxamate ligands, whereas the Co(II), Ni(II), and Zn(II) derivatives all exhibit mononuclear six-coordinate structures with a chelating hydroxamate ligand.     

Dinuclear zinc(II) complexes of tetraiminodiphenol macrocycles and their interactions with carboxylate anions and amino acids. Photoluminescence, equilibria, and structure

The reaction equilibria [H(4)L](2+) + Zn(OAc)(2) right harpoon over left harpoon [Zn(H(2)L)](2+) + 2HOAc (K(1)) and [Zn(H(2)L)](2+) + Zn(OAc)(2) right harpoon over left harpoon [Zn(2)L](2+) + 2HOAc (K(2)), involving zinc acetate and the perchlorate salts of the tetraiminodiphenol macrocycles [H(4)L(1)(-)(3)](ClO(4))(2), the lateral (CH(2))(n)() chains of which vary between n = 2 and n = 4, have been studied by spectrophotometric and spectrofluorimetric titrations in acetonitrile. The photoluminescence behavior of the complexes [Zn(2)L(1)](ClO(4))(2), [Zn(2)L(2)(H(2)O)(2)](ClO(4))(2), [Zn(2)L(2)(mu-O(2)CR)](ClO(4)) (R = CH(3), C(6)H(5), p-CH(3)C(6)H(4), p-OCH(3)C(6)H(4), p-ClC(6)H(4), p-NO(2)C(6)H(4)), and [Zn(2)L(3)(mu-OAc)](ClO(4)) have been investigated. The X-ray crystal structures of the complexes [Zn(2)L(2)(H(2)O)(2)](ClO(4))(2), [Zn(2)L(3)(mu-OAc)](ClO(4)), and [Zn(2)L(2)(mu-OBz)(OBz)(H(3)O)](ClO(4)) have been determined. The complex [Zn(2)L(2)(mu-OBz)(OBz)(H(3)O)](ClO(4)) in which the coordinated water molecule is present as the hydronium ion (H(3)O(+)) on deprotonation gives rise to the neutral dibenzoate-bridged compound [Zn(2)L(2)(mu-OBz)(2)].H(2)O. The equilibrium constants (K) for the reaction [Zn(2)L(2)(H(2)O)(2)](2+) + A(-) right harpoon over left harpoon [Zn(2)L(2)A](+) + 2H(2)O (K), where A(-) = acetate, benzoate, or the carboxylate moiety of the amino acids glycine, l-alanine, l-histidine, l-valine, and l-proline, have been determined spectrofluorimetrically in aqueous solution (pH 6-7) at room temperature. The binding constants (K) evaluated for these systems vary in the range (1-8) x 10(5).     

The first acetimino complexes of Rh(III). 4-imino-2-methylpentan-2-amino-Rh(III) complexes through metal-assisted intramolecular aldol-type condensation of two acetimino ligands

[Rh(Cp)Cl(mu-Cl)](2) (Cp = pentamethylcyclopentadienyl) reacts (i) with [Au(NH=CMe(2))(PPh(3))]ClO(4) (1:2) to give [Rh(Cp)(mu-Cl)(NH=CMe(2))](2)(ClO(4))(2) (1), which in turn reacts with PPh(3) (1:2) to give [Rh(Cp)Cl(NH=CMe(2))(PPh(3))]ClO(4) (2), and (ii) with [Ag(NH=CMe(2))(2)]ClO(4) (1:2 or 1:4) to give [Rh(Cp)Cl(NH=CMe(2))(2)]ClO(4) (3) or [Rh(Cp)(NH=CMe(2))(3)](ClO(4))(2).H(2)O (4.H(2)O), respectively. Complex 3 reacts (i) with XyNC (1:1, Xy = 2,6-dimethylphenyl) to give [Rh(Cp)Cl(NH=CMe(2))(CNXy)]ClO(4) (5), (ii) with Tl(acac) (1:1, acacH = acetylacetone) or with [Au(acac)(PPh(3))] (1:1) to give [Rh(Cp)(acac)(NH=CMe(2))]ClO(4) (6), (iii) with [Ag(NH=CMe(2))(2)]ClO(4) (1:1) to give 4, and (iv) with (PPN)Cl (1:1, PPN = Ph(3)P=N=PPh(3)) to give [Rh(Cp)Cl(imam)]Cl (7.Cl), which contains the imam ligand (N,N-NH=C(Me)CH(2)C(Me)(2)NH(2) = 4-imino-2-methylpentan-2-amino) that results from the intramolecular aldol-type condensation of the two acetimino ligands. The homologous perchlorate salt (7.ClO(4)) can be prepared from 7.Cl and AgClO(4) (1:1), by treating 3 with a catalytic amount of Ph(2)C=NH, in an atmosphere of CO, or by reacting 4with (PPN)Cl (1:1). The reactions of 7.ClO(4) with AgClO(4) and PTo(3) (1:1:1, To = C(6)H(4)Me-4) or XyNC (1:1:1) give [Rh(Cp)(imam)(PTo(3))](ClO(4))(2).H(2)O (8) or [Rh(Cp)(imam)(CNXy)](ClO(4))(2) (9), respectively. The crystal structures of 3 and 7.Cl have been determined.     

Synthesis and characterization of mononuclear zinc aryloxide complexes supported by nitrogen/sulfur ligands possessing an internal hydrogen bond donor

Treatment of a dinuclear zinc hydroxide complex ([(bmnpaZn)(2)(mu-OH)(2)](ClO(4))(2) (1) or [(benpaZn)(2)(mu-OH)(2)](ClO(4))(2) (2)) with excess equivalents of an aryl alcohol derivative (p-HOC(6)H(4)X; X = NO(2), CHO, CN, COCH(3), Br, H, OCH(3)) yielded the nitrogen/sulfur-ligated zinc aryloxide complexes [(bmnpa)Zn(p-OC(6)H(4)NO(2))](ClO(4)) (3), [(benpa)Zn(p-OC(6)H(4)NO(2))](ClO(4)) (4), [(benpa)Zn(p-OC(6)H(4)CHO)](ClO(4)) (5), [(benpa)Zn(p-OC(6)H(4)CN)](ClO(4)) (6), [(benpa)Zn(p-OC(6)H(4)COCH(3))](ClO(4)) x 0.5H(2)O (7), [(benpa)Zn(p-OC(6)H(4)Br)](ClO(4)) (8), [(benpa)Zn(p-OC(6)H(5))](ClO(4)) (9), and [(benpa)Zn(p-OC(6)H(5)OCH(3))](ClO(4)) (10). The solid state structures of 2, 3, 5, and 6 have been determined by X-ray crystallography. While 3 and 6 exhibit a mononuclear zinc ion possessing a distorted five-coordinate trigonal bipyramidal geometry, in 5 each zinc center exhibits a distorted six-coordinate octahedral geometry resulting from coordination of the aldehyde carbonyl oxygen of another zinc-bound aryloxide ligand, yielding a chain-type structure. Zinc coordination of the aldehyde carbonyl of 5 is indicated by a large shift (>40 cm(-)(1)) to lower energy of the carbonyl stretching vibration (nu(C[double bond]O) in solid state FTIR spectra of the complex. In the solid state structures of 3, 5, and 6, a hydrogen-bonding interaction is found between N(3)-H of the supporting bmnpa/benpa ligand and the zinc-bound oxygen atom of the aryloxide ligand (N(3)...O(1) approximately 2.78 A). Solution (1)H and (13)C NMR spectra of 3-10 in CD(3)CN and FTIR spectra in CH(3)CN are consistent with all of the aryloxide complexes having a similar solution structure, with retention of the hydrogen-bonding interaction involving N(3)-H and the oxygen atom of the zinc-coordinated aryloxide ligand. For this family of zinc aryloxide complexes, a correlation was discovered between the chemical shift position of the N(3)-H proton resonance and the pK(a) of the parent aryl alcohol. This correlation indicates that the strength of the hydrogen-bonding interaction involving the zinc-bound aryloxide oxygen is increasing as the aryloxide moiety increases in basicity.     

Multicomponent assembly of anionic and neutral decanuclear copper(II) phosphonate cages

A multicomponent synthetic strategy involving copper(II) ions, tert-butylphosphonic acid (t-BuPO(3)H(2)) and 3-substituted pyrazole ligands has been adopted for the synthesis of soluble molecular copper(II) phosphonates. The use of six different 3-substituted pyrazoles, 3-R-PzH [R = H, Me, CF(3), Ph, 2-pyridyl (2-Py), and 2-methoxyphenyl (2-MeO-C(6)H(4))] as ancillary ligands afforded nine different decanuclear cages, [Cu(5)(μ(3)-OH)(2)(O(3)P-t-Bu)(3)(3-R-Pz)(2)(X)(2)](2)·(Y) where R = H, X = t-BuPO(3)H, and Y = (Et(3)NH(+))(4)(solvent) (1); R = Me, X = 3-MePzH, and Y = solvent (2); R = Me, X = t-BuPO(3)H, and Y = (Et(3)NH(+))(4)(solvent) (3); R = CF(3), X = t-BuPO(3)H, and Y = (Et(3)NH(+))(4)(solvent) (4); R = Ph, X = 3-PhPzH, and Y = solvent (5); R = 2-Py, X = 0.5 MeOH, and Y = solvent (6); R = 2-Py, X = none, and Y = solvent (7); R = 2-Py, X = H(2)O, and Y = (Et(3)NH(+)·PF(6)(-))(2)(solvent) (8); R = 2-MeO-C(6)H(4), X = MeOH or 0.5:0.5 MeOH/H(2)O, and Y = solvent (9). Compounds 1-6, 8, and 9 were isolated using a direct synthetic method which involves the reaction of copper(II) salts and the ligands, while 7 was obtained from an indirect route involving the reaction of preformed copper-pyridylpyrazolate precursor complexes and t-BuPO(3)H(2). The decametallic compounds 1-9 possess a butterfly shaped core. The core of the cages 1, 3, and 4 are tetraanionic and contain more phosphonates than pyrazole ligands, while the other cages are neutral and contain more pyrazoles than phosphonate ligands. Compounds 1-6 have been studied by electrospray ionization-high-resolution mass spectrometry (ESI-HRMS). The decanuclear cage 6 was shown to be a good plasmid modifier.     

Zinc(II), cadmium(II), mercury(II), and ethylmercury(II) complexes of phosphinothiol ligands

Neutral zinc, cadmium, mercury(II), and ethylmercury(II) complexes of a series of phosphinothiol ligands, PhnP(C6H3(SH-2)(R-3))3-n (n = 1, 2; R = H, SiMe3) have been synthesized and characterized by IR and NMR ((1)H, (13)C, and (31)P) spectroscopy, FAB mass spectrometry, and X-ray structural analysis. The compounds [Zn{PhP(C6H4S-2)2}] (1) and [Cd{Ph2PC6H4S-2}2] (2) have been synthesized by electrochemical oxidation of anodic metal (zinc or cadmium) in an acetonitrile solution of the appropriate ligand. The presence of pyridine in the electrolytic cell affords the mixed complexes [Zn{PhP(C6H4S-2)2}(py)] (3) and [Cd{PhP(C6H4S-2)2}(py)] (4). [Hg{Ph2PC6H4S-2}2] (5) and [Hg{Ph2PC6H3(S-2)(SiMe3-3)}2] (6) were obtained by the addition of the appropriate ligand to a solution of mercury(II) acetate in methanol in the presence of triethylamine. [EtHg{Ph2PC6H4S-2}] (7), [EtHg{Ph2P(O)C6H3(S-2)(SiMe3-3)}] (8), [{EtHg}2{PhP(C6H4S-2)2}] (9), and [{EtHg}2{PhP(C6H3(S-2)(SiMe3-3))2}] (10) were obtained by reaction of ethylmercury(II) chloride with the corresponding ligand in methanol. In addition, in the reactions of EtHgCl with Ph2PC6H4SH-2 and with the potentially tridentate ligand PhP(C6H3(SH-2)(SiMe3-3)) 2, cleavage of the Hg-C bond was observed with the formation of [Hg{Ph2PC6H4S-2}2] (5) and [Hg(EtHg) 2{PhP(O)(C6H3(S-2)(SiMe3-3))2}2] (11), respectively, and the corresponding hydrocarbon. The crystal structures of [Zn3{PhP(C6H4S-2)2}2{PhP(O)(C6H4S-2)2}] (1*), [Cd2{Ph2PC6H4S-2}3{Ph2P(O)C6H4S-2}] (2*), 3, 5, 6, [EtHg{Ph2P(O)C6H4S-2}] (7*), 8, 9, [{EtHg}2{PhP(O)(C6H3(S-2)(SiMe3-3))2}] (10*), and 11 are discussed. The molecular structures of 1, 2, 4, 7, and 10 have also been studied by means of density functional theory (DFT) calculations.     

2-Aminoisobutyric acid in Co(II) and Co(II)/Ln(III) chemistry: homometallic and heterometallic clusters

The synthesis and magnetic properties of 13 new homo- and heterometallic Co(II) complexes containing the artificial amino acid 2-amino-isobutyric acid, aibH, are reported: [Co(II)(4)(aib)(3)(aibH)(3)(NO(3))](NO(3))(4)·2.8CH(3)OH·0.2H(2)O (1·2.8CH(3)OH·0.2H(2)O), {Na(2)[Co(II)(2)(aib)(2)(N(3))(4)(CH(3)OH)(4)]}(n) (2), [Co(II)(6)La(III)(aib)(6)(OH)(3)(NO(3))(2)(H(2)O)(4)(CH(3)CN)(2)]·0.5[La(NO(3))(6)]·0.75(ClO(4))·1.75(NO(3))·3.2CH(3)CN·5.9H(2)O (3·3.2CH(3)CN·5.9H(2)O), [Co(II)(6)Pr(III)(aib)(6)(OH)(3)(NO(3))(3)(CH(3)CN)(6)]·[Pr(NO(3))(5)]·0.41[Pr(NO(3))(3)(ClO(4))(0.5)(H(2)O)(1.5)]·0.59[Co(NO(3))(3)(H(2)O)]·0.2(ClO(4))·0.25H(2)O (4·0.25H(2)O), [Co(II)(6)Nd(III)(aib)(6)(OH)(3)(NO(3))(2.8)(CH(3)OH)(4.7)(H(2)O)(1.5)]·2.7(ClO(4))·0.5(NO(3))·2.26CH(3)OH·0.24H(2)O (5·2.26CH(3)OH·0.24H(2)O), [Co(II)(6)Sm(III)(aib)(6)(OH)(3)(NO(3))(3)(CH(3)CN)(6)]·[Sm(NO(3))(5)]·0.44[Sm(NO(3))(3)(ClO(4))(0.5)(H(2)O)(1.5)]·0.56[Co(NO(3))(3)(H(2)O)]·0.22(ClO(4))·0.3H(2)O (6·0.3H(2)O), [Co(II)(6)Eu(III)(aib)(6)(OH)(3)(NO(3))(3)(CH(3)OH)(4.87)(H(2)O)(1.13)](ClO(4))(2.5)(NO(3))(0.5)·2.43CH(3)OH·0.92H(2)O (7·2.43CH(3)OH·0.92H(2)O), [Co(II)(6)Gd(III)(aib)(6)(OH)(3)(NO(3))(2.9)(CH(3)OH)(4.9)(H(2)O)(1.2)]·2.6(ClO(4))·0.5(NO(3))·2.58CH(3)OH·0.47H(2)O (8·2.58CH(3)OH·0.47H(2)O), [Co(II)(6)Tb(III)(aib)(6)(OH)(3)(NO(3))(3)(CH(3)CN)(6)]·[Tb(NO(3))(5)]·0.034[Tb(NO(3))(3)(ClO(4))(0.5)(H(2)O)(0.5)]·0.656[Co(NO(3))(3)(H(2)O)]·0.343(ClO(4))·0.3H(2)O (9·0.3H(2)O), [Co(II)(6)Dy(III)(aib)(6)(OH)(3)(NO(3))(2.9)(CH(3)OH)(4.92)(H(2)O)(1.18)](ClO(4))(2.6)(NO(3))(0.5)·2.5CH(3)OH·0.5H(2)O (10·2.5CH(3)OH·0.5H(2)O), [Co(II)(6)Ho(III)(aib)(6)(OH)(3)(NO(3))(3)(CH(3)CN)(6)]·0.27[Ho(NO(3))(3)(ClO(4))(0.35)(H(2)O)(0.15)]·0.656[Co(NO(3))(3)(H(2)O)]·0.171(ClO(4)) (11), [Co(II)(6)Er(III)(aib)(6)(OH)(4)(NO(3))(2)(CH(3)CN)(2.5)(H(2)O)(3.5)](ClO(4))(3)·CH(3)CN·0.75H(2)O (12·CH(3)CN·0.75H(2)O), and [Co(II)(6)Tm(III)(aib)(6)(OH)(3)(NO(3))(3)(H(2)O)(6)]·1.48(ClO(4))·1.52(NO(3))·3H(2)O (13·3H(2)O). Complex 1 describes a distorted tetrahedral metallic cluster, while complex 2 can be considered to be a 2-D coordination polymer. Complexes 3-13 can all be regarded as metallo-cryptand encapsulated lanthanides in which the central lanthanide ion is captivated within a [Co(II)(6)] trigonal prism. dc and ac magnetic susceptibility studies have been carried out in the 2-300 K range for complexes 1, 3, 5, 7, 8, 10, 12, and 13, revealing the possibility of single molecule magnetism behavior for complex 10.     

Ligand design for alkali-metal-templated self-assembly of unique high-nuclearity CuII aggregates with diverse coordination cage units: crystal structures and properties

The construction of two unique, high-nuclearity Cu(II) supramolecular aggregates with tetrahedral or octahedral cage units, [(mu(3)-Cl)[Li subset Cu(4)(mu-L(1))(3)](3)](ClO(4))(8)(H(2)O)(4.5) (1) and [[Na(2) subset Cu(12)(mu-L(2))(8)(mu-Cl)(4)](ClO(4))(8)(H(2)O)(10)(H(3)O(+))(2)](infinity) (2) by alkali-metal-templated (Li(+) or Na(+)) self-assembly, was achieved by the use of two newly designed carboxylic-functionalized diazamesocyclic ligands, N,N'-bis(3-propionyloxy)-1,4-diazacycloheptane (H(2)L(1)) or 1,5-diazacyclooctane-N,N'-diacetate acid (H(2)L(2)). Complex 1 crystallizes in the trigonal R3c space group (a = b = 20.866(3), c = 126.26(4) A and Z = 12), and 2 in the triclinic P1 space group (a = 13.632(4), b = 14.754(4), c = 19.517(6) A, alpha = 99.836(6), beta = 95.793(5), gamma = 116.124(5) degrees and Z = 1). By subtle variation of the ligand structures and the alkali-metal templates, different polymeric motifs were obtained: a dodecanuclear architecture 1 consisting of three Cu(4) tetrahedral cage units with a Li(+) template, and a supramolecular chain 2 consisting of two crystallographically nonequivalent octahedral Cu(6) polyhedra with a Na(+) template. The effects of ligand functionality and alkali metal template ions on the self-assembly processes of both coordination supramolecular aggregates, and their magnetic behaviors are discussed in detail.     

Oxamato-bridged trinuclear NiIICuIINiII complexes: a new (NiIICuIINiII)2 hexanuclear complex and supramolecular structures. Characterization and magnetic properties

Eight oxamato-bridged heterotrinuclear Ni(II)Cu(II)Ni(II) complexes of formula ([Ni(H(2)O)(dpt)](2)(mu-Cu(H(2)O)(opba)))(ClO(4))2 (1), ([Ni(H(2)O)(dien)](2)(mu-Cu(pba)))(ClO(4))(2).6H(2)O (2), ([Ni(H(2)O)(Medpt)](2)(mu-Cu(OHpba)))(ClO(4))(2).4H(2)O (3), ([Ni(H(2)O)(dien)](2)(mu-Cu(Me(2)pba)))(ClO(4))(2).2.5H(2)O (4), ([Ni(H(2)O)(dpt)](2)(mu-Cu(Me(2)pba)))(ClO(4))(2).2H(2)O (5), ([Ni(H(2)O)(dien)](2)(mu-Cu(OHpba)))(ClO(4))(2).4H(2)O (6), ([Ni(2)(dpt)(2)(mu-Cu(H(2)O)(pba))](2)(mu-N(3))(2))Na(2)(ClO(4))(4).6H(2)O (7), and ([Cu(H(2)O)(2)(dpt)Ni(2)(H(2)O)(dpt)(2)](mu-H(2)Me(2)pba(2-)))(ClO(4))(4).3H(2)O (8) in which opba = o-phenylenbis(oxamato), pba = 1,3-propylenebis(oxamato), OHpba = 2-hydroxy-1,3-propylenebis(oxamato), Me(2)pba = 2,2-dimethyl-1,3-propylenbis(oxamato), dpt = 3,3'-diaminodipropylamine, dien = 2,2'-diaminodiethylamine, and Medpt = 3,3'-diamino-N-methyldipropylamine were synthesized and characterized. The crystal structures of 1, 7, and 8 were solved. For complex 1, the trinuclear entities are linked by hydrogen bonds forming a one-dimensional system, and for complex 8, the presence of van der Waals interactions gives a one-dimensional system, too. For complex 7, the trinuclear entities are self-assembled by azido ligands, given a hexanuclear system; each of these hexanuclear entities are self-assembled through two [Na(O)(3)(H(2)O)(3)] octahedral-sharing one-edge entities, given a one-dimensional system. The magnetic behavior of complexes 2-7 was investigated by variable-temperature magnetic susceptibility measurements. Complexes 2-6 exhibit the minimum characteristic of this kind of polymetallic species with an irregular spin state structure. The Jvalue through the oxamato bridge varied between -88 cm(-1) (for 6) and -111.2 cm(-1) (for 5). For complex 7, the values obtained were J(1) = -101.7 cm(-1) (through the oxamato ligand) and J(2) = -3.2 cm(-1) (through the azido ligand).     

Aggregation control by homologous tripodal tetradentate amino acid ligands in oxo-bridged diiron(III) aquo complexes

Isoelectronic oxo-bridged diiron(III) aquo complexes of the homologous tripodal tetradentate amino acid ligands, N,N'-bis(2-pyridylmethyl)-3-aminoacetate (bpg(-)) and N,N'-bis(2-pyridylmethyl)-3-aminopropionate (bpp(-)), containing [(H(2)O)Fe(III)-(mu-O)-Fe(III)(H(2)O)](4+) cores, oligomerise, respectively, by dehydration and deprotonation, or by dehydration only, in reversible reactions. In the solid state, [Fe(2)(O)(bpp)(2)(H(2)O)(2)](ClO(4))(2) (1(ClO(4))(2)) exhibits stereochemistry identical to that of [Fe(2)(O)(bpg)(2)(H(2)O)(2)](ClO(4))(2) (2(ClO(4))(2)), with the ligand carboxylate donor oxygen atoms and the water molecules located cis to the oxo bridge and the tertiary amine group trans to it. Despite their structural similarity, 1(2+) and 2(2+) display markedly different aggregation behaviour in solution. In the absence of significant water, 1(2+) dehydrates and dimerises to give the tetranuclear complex, [Fe(4)(O)(2)(bpp)(4)](ClO(4))(4) (3(ClO(4))(4)), in which the carboxylate groups of the four bpp(-) ligands act as bridging groups between two [Fe(2)(O)(bpp)(2)](2+) units. Under similar conditions, 2(2+) dehydrates and deprotonates to form dinuclear and trinuclear oligomers, [Fe(2)(O)(OH)(bpg)(2)](ClO(4)) (4ClO(4)) and [Fe(3)(O)(2)(OH)(bpg)(3)](ClO(4)) (5(ClO(4))), related by addition of 'Fe(O)(bpg)' units. The trinuclear 5(ClO(4)), characterised crystallographically as two solvates 5(ClO(4)).3H(2)O and 5(ClO(4)).2MeOH, is based on a hexagonal [Fe(3)(O)(2)(OH)(bpg)(3)](+) unit, formally containing one hydroxo and two oxo bridges. The different aggregation behaviour of 1(ClO(4))(2) and 2(ClO(4))(2) results from the difference of one methylene group in the pendant carboxylate arms of the amino acid ligands.     

Pt]2Pb trinuclear systems: impact of the anionic platinum fragment on the lead environment and photoluminescence

A comparison of the solid structures of three novel trinuclear sandwich Pt 2Pb systems (NBu 4) 2[{Pt(C identical withCTol) 4} 2Pb(OH 2) 2] 1, [{Pt(bzq)(C identical withCPh) 2} 2Pb] 2, and (NBu 4)[{Pt(bzq)(C identical withCC 6H 4-CF 3-4) 2} 2Pb(O 2ClO 2)] 4 (NBu 4[ 3.(O 2ClO 2)]) with that of the previously reported (NBu 4) 2[{Pt(C 6F 5) 4} 2Pb] 5 showed that the local environment of Pb (II) is highly sensitive to the nature of the anionic platinate(II) precursors. The photoluminescence (PL) studies of all 1- 5 complexes revealed a dependence of PL on the structure type. Thus, complexes 1 and 5 exhibit metal centered emissions ( 1, 497 nm, 77 K; 5, 539 nm, varphi = 0.43, 298 K) related to the linear ( 5) or bent ( 1 Pt-Pb-Pt 149.9 degrees ) trinuclear entities. However, in complexes 2- 4, that have unprecedented Pb (II)...eta (1)(C identical withCR) bonding interactions and very short Pt...Pb and Pt...Pt distances, the emissive state in solid state (77 K) is attributed to a (3)MLM'CT [Pt(1)pi(C identical withCR)-->Pt(2)/Pb(sp)pi*(C identical withCR)] state mixed with some pipi* excimeric character in neutral complexes 2 (R = Ph) and 3 (R = C 6H 4-CF 3-4), and in the case of the adduct (NBu 4)[{Pt(bzq)(C identical withCC 6H 4-CF 3-4) 2} 2Pb(O 2ClO 2)] 4 modified also by Pb (II)...O (O 2ClO 2 (-)) contacts.     

Tetranuclear manganese complexes with dimer-of-dimer and ladder structures from the use of a bis-bipyridyl ligand

The reaction of the bis-chelating ligand 1,2-bis(2,2'-bipyridine-6-yl)ethane (L) with the trinuclear species of formula [Mn(3)O(O(2)CR)(6)(py)(3)](ClO(4)) (R = Me (1); R = Et (2); R = Ph (3)) has afforded the new tetranuclear mixed-valent complexes [Mn(4)O(2)(O(2)CR)(4)L(2)](ClO(4))(2) (R = Me (4); R = Et (5); R = Ph (6)) and [Mn(4)O(2)(OMe)(3)(O(2)CR)(2)L(2)(MeOH)](ClO(4))(2) (R = Me (7); R = Et (8); R = Ph (9)). Complexes 4-6 were obtained in yields of 20%, 44%, and 37%, respectively. They are mixed-valent, with an average Mn oxidation state of +2.5. Complexes 7-9 were obtained in yields of 57%, 65%, and 70%, respectively. They are also mixed-valent, but with an average Mn oxidation state of +2.75. Complexes 4 x 2THF and 9 x 3MeOH x H(2)O crystallize in the triclinic space group P1 macro and contain [Mn(4)(mu(3)-O)(2)](6+) and [Mn(4)(mu(3)-O)(2)(mu-OMe)(2)](5+) cores, respectively, the latter being a new structural type in the family of Mn(4) complexes. Reactivity studies of 4-9 have shown that 4-6 can be converted into 7-9, respectively, and vice versa. The magnetic properties of 5 and 9 have been studied by dc and ac magnetic susceptibility techniques. Complex 5 displays antiferromagnetic coupling between its Mn ions resulting in a spin ground state of S = 0. Complex 9 also displays antiferromagnetic coupling, but the resulting ground state is S = (7)/(2), as confirmed by fitting magnetization versus field data collected for 9 at low temperatures, which gave S = (7)/(2), D = -0.77 cm(-1), and g = 1.79. Complex 9 exhibits a frequency-dependent out-of-phase ac susceptibility peak, indicative of the slow magnetization relaxation that is diagnostic of single-molecule magnetism behavior.     

Regioselective functionalization of iminophosphoranes through Pd-mediated C-H bond activation: C-C and C-X bond formation

The orthopalladation of iminophosphoranes [R(3)P=N-C(10)H(7)-1] (R(3) = Ph(3) 1, p-Tol(3) 2, PhMe(2) 3, Ph(2)Me 4, N-C(10)H(7)-1 = 1-naphthyl) has been studied. It occurs regioselectively at the aryl ring bonded to the P atom in 1 and 2, giving endo-[Pd(μ-Cl)(C(6)H(4)-(PPh(2=N-1-C(10)H(7))-2)-κ-C,N](2) (5) or endo-[Pd(μ-Cl)(C(6)H(3)-(P(p-Tol)(2)=N-C(10)H(7)-1)-2-Me-5)-κ-C,N](2) (6), while in 3 the 1-naphthyl group is metallated instead, giving exo-[Pd(μ-Cl)(C(10)H(6)-(N=PPhMe(2))-8)-κ-C,N](2) (7). In the case of 4, orthopalladation at room temperature affords the kinetic exo isomer [Pd(μ-Cl)(C(10)H(6)-(N=PPh(2)Me)-8)-κ-C,N](2) (11exo), while a mixture of 11exo and the thermodynamic endo isomer [Pd(μ-Cl)(C(6)H(4)-(PPhMe=N-C(10)H(7)-1)-2)-κ-C,N](2) (11endo) is obtained in refluxing toluene. The heating in toluene of the acetate bridge dimer [Pd(μ-OAc)(C(10)H(6)-(N=PPh(2)Me)-8)-κ-C,N](2) (13exo) promotes the facile transformation of the exo isomer into the endo isomer [Pd(μ-OAc)(C(6)H(4)-(PPhMe=N-C(10)H(7)-1)-2)-κ-C,N](2) (13endo), confirming that the exo isomers are formed under kinetic control. Reactions of the orthometallated complexes have led to functionalized molecules. The stoichiometric reactions of the orthometallated complexes [Pd(μ-Cl)(C(10)H(6)-(N=PPhMe(2))-8)-κ-C,N](2) (7), [Pd(μ-Cl)(C(6)H(4)-(PPh(2)[=NPh)-2)](2) (17) and [Pd(μ-Cl)(C(6)H(3)-(C(O)N=PPh(3))-2-OMe-4)](2) (18) with I(2) or with CO results in the synthesis of the ortho-halogenated compounds [PhMe(2)P=N-C(10)H(6)-I-8] (19), [I-C(6)H(4)-(PPh(2)=NPh)-2] (21) and [Ph(3)P=NC(O)C(6)H(3)-I-2-OMe-5] (23) or the heterocycles [C(10)H(6)-(N=PPhMe(2))-1-(C(O))-8]Cl (20), [C(6)H(5)-(N=PPh(2)-C(6)H(4)-C(O)-2]ClO(4) (22) and [C(6)H(3)-(C(O)-1,2-N-PPh(3))-OMe-4]Cl (24).     

Thioester hydrolysis reactivity of zinc hydroxide complexes: investigating reactivity relevant to glyoxalase II enzymes

A recently reported binuclear zinc hydroxide complex [(L(1)Zn(2))(mu-OH)](ClO(4))(2) (, L(1) = 2,6-bis[(bis(2-pyridylmethyl)amino)methyl]-4-methylphenolate monoanion) containing a single bridging hydroxide was examined for thioester hydrolysis reactivity. Treatment of it with hydroxyphenylthioacetic acid S-methyl ester in dry CD(3)CN results in no reaction after approximately 65 h at 45(1) degrees C. Binuclear zinc hydroxide complexes of the N-methyl-N-((6-neopentylamino-2-pyridyl)methyl)-N-((2-pyridyl)methyl)amine (L(2)) and N-methyl-N-((6-neopentylamino-2-pyridyl)methyl)-N-((2-pyridyl)ethyl)amine (L(3)) chelate ligands were prepared by treatment of each ligand with molar equivalent amounts of Zn(ClO(4))(2).6H(2)O and KOH in methanol. These complexes, [(L(2)Zn)(2)(mu-OH)(2)](ClO(4))(2) and [(L(3)Zn)(2)(mu-OH)(2)](ClO(4))(2) (), which have been structurally characterized by X-ray crystallography, behave as 1 : 1 electrolytes in acetonitrile, indicating that the binuclear cations dissociate into monomeric zinc hydroxide species in solution. Treatment of them with one equivalent of hydroxyphenylthioacetic acid S-methyl ester per zinc center in acetonitrile results in the formation of a zinc alpha-hydroxycarboxylate complex, [(L(2))Zn(O(2)CCH(OH)Ph)]ClO(4).1.5H(2)O or [(L(3))Zn(O(2)CCH(OH)Ph)]ClO(4).1.5H(2)O, and CH(3)SH. These reactions, to our knowledge, are the first reported examples of thioester hydrolysis mediated by zinc hydroxide complexes. The results of this study suggest that a terminal Zn-OH moiety may be required for hydrolysis reactivity with a thioester substrate.     

Anion induced formation of supramolecular associations involving lone pair-π and anion-π interactions in Co(II) malonate complexes: experimental observations, Hirshfeld surface analyses and DFT studies

Three Co(II)-malonate complexes, namely, (C(5)H(7)N(2))(4)[Co(C(3)H(2)O(4))(2)(H(2)O)(2)](NO(3))(2) (1), (C(5)H(7)N(2))(4)[Co(C(3)H(2)O(4))(2)(H(2)O)(2)](ClO(4))(2) (2), and (C(5)H(7)N(2))(4)[Co(C(3)H(2)O(4))(2)(H(2)O)(2)](PF(6))(2) (3) [C(5)H(7)N(2) = protonated 2-aminopyridine, C(3)H(4)O(4) = malonic acid, NO(3)(-) = nitrate, ClO(4)(-) = perchlorate, PF(6)(-) = hexafluorophosphate], have been synthesized from purely aqueous media, and their crystal structures have been determined by single crystal X-ray diffraction. A thorough analysis of Hirshfeld surfaces and fingerprint plots facilitates a comparison of intermolecular interactions in 1-3, which are crucial in building supramolecular architectures. When these complexes are structurally compared with their previously reported analogous Ni(II) or Mg(II) compounds, a very interesting feature regarding the role of counteranions has emerged. This phenomenon can be best described as anion-induced formation of extended supramolecular networks of the type lone pair-π/π-π/π-anion-π/π-lone pair and lone pair-π/π-π/π-anion involving various weak forces like lone pair-π, π-π, and anion-π interactions. The strength of these π contacts has been estimated using DFT calculations (M06/6-31+G*), and the formation energy of the supramolecular networks has been also evaluated. The influence of the anion (NO(3)(-), ClO(4)(-), and PF(6)(-)) on the total interaction energy of the assembly is also studied.     

Electrospray Ionization Mass Spectral Characterization of Transient Iron Species of Bioinorganic Relevance

Strategies have been developed to obtain electrospray ionization mass spectral data on short-lived intermediates derived from the reactions of non-heme iron complexes with peroxides. The molecular composition of a transient green intermediate generated from [Fe(2)O(5-Me(3)-TPA)(2)(OH)(H(2)O)](ClO(4))(3) with H(2)O(2) in CH(3)CN at -40 degrees C was determined by introducing the solution via a precooled syringe to the inlet of the mass spectrometer. The observation of prominent ion clusters in both positive and negative mass regions, together with isotope distribution patterns characteristic of the number of associated ClO(4) ions, allows its formulation as [Fe(2)(O)(2)(5-Me(3)-TPA)(2)](ClO(4))(3). The molecular composition of a transient blue species derived from the reaction of [Fe(2)O(TPA)(2)(H(2)O)(ClO(4))](ClO(4))(3) with excess benzyl alcohol and (t)BuOOH at -40 degrees C was also determined. Due to its limited stability even at -40 degrees C, the blue intermediate was generated in a cooled mixing tee from its precursor components and directly introduced into the mass spectrometer. Its formulation as {[Fe(TPA)(OO(t)Bu)(ROH)](ClO(4))}(+) (R = H or CH(2)Ph) is based on the masses observed, isotope distribution patterns, the observation of expected shifts in the mass values by appropriate substitutions, and tandem mass spectral data. These transient species relate to possible intermediates of non-heme iron enzymes.     

Influence of ligand polarizability on the reversible binding of O2 by trans-[Rh(X)(XNC)(PPh3)2] (X = Cl, Br, SC6F5, C2Ph; XNC = xylyl isocyanide). Structures and a kinetic study

The complexes trans-[Rh(X)(XNC)(PPh 3) 2] (X = Cl, 1; Br, 2; SC 6F 5, 3; C 2Ph, 4; XNC = xylyl isocyanide) combine reversibly with molecular oxygen to give [Rh(X)(O 2)(XNC)(PPh 3) 2] of which [Rh(SC 6F 5)(O 2)(XNC)(PPh 3) 2] ( 7) and [Rh(C 2Ph)(O 2)(XNC)(PPh 3) 2] ( 8) are sufficiently stable to be isolated in crystalline form. Complexes 2, 3, 4, and 7 have been structurally characterized. Kinetic data for the dissociation of O 2 from the dioxygen adducts of 1- 4 were obtained using (31)P NMR to monitor changes in the concentration of [Rh(X)(O 2)(XNC)(PPh 3) 2] (X = Cl, Br, SC 6F 5, C 2Ph) resulting from the bubbling of argon through the respective warmed solutions (solvent chlorobenzene). From data recorded at temperatures in the range 30-70 degrees C, activation parameters were obtained as follows: Delta H (++) (kJ mol (-1)): 31.7 +/- 1.6 (X = Cl), 52.1 +/- 4.3 (X = Br), 66.0 +/- 5.8 (X = SC 6F 5), 101.3 +/- 1.8 (X = C 2Ph); Delta S (++) (J K (-1) mol (-1)): -170.3 +/- 5.0 (X = Cl), -120 +/- 13.6 (X = Br), -89 +/- 18.2 (X = SC 6F 5), -6.4 +/- 5.4 (X = C 2Ph). The values of Delta H (++) and Delta S (++) are closely correlated (R (2) = 0.9997), consistent with a common dissociation pathway along which the rate-determining step occurs at a different position for each X. Relative magnitudes of Delta H (++) are interpreted in terms of differing polarizabilities of ligands X.     

Synthesis and reactivity of Ir(I) and Ir(III) complexes with MeNH2, Me2C=NR (R = H, Me), C,N-C6H4{C(Me)=N(Me)}-2, and N,N'-RN=C(Me)CH2C(Me2)NHR (R = H, Me) ligands

Complexes [Ir(Cp*)Cl(n)(NH2Me)(3-n)]X(m) (n = 2, m = 0 (1), n = 1, m = 1, X = Cl (2a), n = 0, m = 2, X = OTf (3)) are obtained by reacting [Ir(Cp*)Cl(mu-Cl)]2 with MeNH2 (1:2 or 1:8) or with [Ag(NH2Me)2]OTf (1:4), respectively. Complex 2b (n = 1, m = 1, X = ClO 4) is obtained from 2a and NaClO4 x H2O. The reaction of 3 with MeC(O)Ph at 80 degrees C gives [Ir(Cp*){C,N-C6H4{C(Me)=N(Me)}-2}(NH2Me)]OTf (4), which in turn reacts with RNC to give [Ir(Cp*){C,N-C6H4{C(Me)=N(Me)}-2}(CNR)]OTf (R = (t)Bu (5), Xy (6)). [Ir(mu-Cl)(COD)]2 reacts with [Ag{N(R)=CMe2}2]X (1:2) to give [Ir{N(R)=CMe2}2(COD)]X (R = H, X = ClO4 (7); R = Me, X = OTf (8)). Complexes [Ir(CO)2(NH=CMe2)2]ClO4 (9) and [IrCl{N(R)=CMe2}(COD)] (R = H (10), Me (11)) are obtained from the appropriate [Ir{N(R)=CMe2}2(COD)]X and CO or Me4NCl, respectively. [Ir(Cp*)Cl(mu-Cl)]2 reacts with [Au(NH=CMe2)(PPh3)]ClO4 (1:2) to give [Ir(Cp*)(mu-Cl)(NH=CMe2)]2(ClO4)2 (12) which in turn reacts with PPh 3 or Me4NCl (1:2) to give [Ir(Cp*)Cl(NH=CMe2)(PPh3)]ClO4 (13) or [Ir(Cp*)Cl2(NH=CMe2)] (14), respectively. Complex 14 hydrolyzes in a CH2Cl2/Et2O solution to give [Ir(Cp*)Cl2(NH3)] (15). The reaction of [Ir(Cp*)Cl(mu-Cl)]2 with [Ag(NH=CMe2)2]ClO4 (1:4) gives [Ir(Cp*)(NH=CMe2)3](ClO4)2 (16a), which reacts with PPNCl (PPN = Ph3=P=N=PPh3) under different reaction conditions to give [Ir(Cp*)(NH=CMe2)3]XY (X = Cl, Y = ClO4 (16b); X = Y = Cl (16c)). Equimolar amounts of 14 and 16a react to give [Ir(Cp*)Cl(NH=CMe2)2]ClO4 (17), which in turn reacts with PPNCl to give [Ir(Cp*)Cl(H-imam)]Cl (R-imam = N,N'-N(R)=C(Me)CH2C(Me)2NHR (18a)]. Complexes [Ir(Cp*)Cl(R-imam)]ClO4 (R = H (18b), Me (19)) are obtained from 18a and AgClO4 or by refluxing 2b in acetone for 7 h, respectively. They react with AgClO4 and the appropriate neutral ligand or with [Ag(NH=CMe2)2]ClO4 to give [Ir(Cp*)(R-imam)L](ClO4)2 (R = H, L = (t)BuNC (20), XyNC (21); R = Me, L = MeCN (22)) or [Ir(Cp*)(H-imam)(NH=CMe2)](ClO4)2 (23a), respectively. The later reacts with PPNCl to give [Ir(Cp*)(H-imam)(NH=CMe2)]Cl(ClO4) (23b). The reaction of 22 with XyNC gives [Ir(Cp*)(Me-imam)(CNXy)](ClO4)2 (24). The structures of complexes 15, 16c and 18b have been solved by X-ray diffraction methods.     

Hydrogencyanamido bridged multinuclear copper(II) complexes: from strong antiferromagnetic couplings to weak ferromagnetic couplings

In the presence of ammonia, the reactions of cyanamide and Cu(II) ions with different organic blocking ligands afford three hydrogencyanamido bridged dinuclear complexes: [(dmbpy)(4)Cu(2)(HNCN)](ClO(4))(3)·H(2)O (1, dmbpy = 4,4'-dimethyl-2,2'-bipyridine), [(phen)(4)Cu(2)(HNCN)](ClO(4))(3)·2H(2)O (2, phen = 1,10-phenanthroline) and [(bpy)(2)Cu(2)(HNCN)(2)(ClO(4))(2)] (3, bpy = 2,2'-bipyridine), respectively. However, using the di(2-pyridyl)ketone (dpk) ligand in similar experimental conditions, an interesting reaction between the hydrogencyanamido anion and dpk is observed. Using Cu(ClO(4))·6H(2)O or Co(ClO(4))·6H(2)O as the metal source, it gives the mixed bridged hexanuclear complex [(dpk·OMe)(4)(dpk·NCN)(2)Cu(6)(H(2)O)(2)](ClO(4))(4) (4), or the mononuclear complex [(dpk·OMe)(dpk·HNCN)Co](ClO(4))·2H(2)O (5), respectively. Their structures are characterized by single crystal X-ray diffraction analyses. Magnetic measurements reveal moderate antiferromagnetic interaction between the Cu(II) ions in complex 1, weak ferromagnetic coupling in complex 2, and strong antiferromagnetic interactions for complexes 3 and 4. The magnetostructural correlations of these complexes are discussed.