Structural aspects of copper catalyzed atom transfer radical polymerization

The stereochemistry of the copper(II) ion in the solid-state—some recent perspectives linking the Jahn–Teller effect, vibronic coupling, structure correlation analysis, structural pathways and comparative X-ray crystallography

The application of continuous symmetry measures to the description of the structures of penta-coordinate complexes is discussed. The characteristic values of the trigonal bipyramid symmetry measure, S(TBP), for molecules with square pyramidal (SP) or intermediate geometries corresponding to a Berry pseudorotation coordinate are established. The experimental data from a reference set comprising 71 structures of more than 40 homoleptic transition metal complexes (including organometallic molecules and inorganic solids) and four EPh5 derivatives of Group 15 elements are consistent with the Berry pathway. The structures of several families of transition metal complexes are analyzed in the light of the variations of S(TBP) corresponding to other distortions of the ideal TBP, including bond stretch or non-Berry angular distortion modes. The families of compounds analyzed are represented by the general formulae [OMX4]−, [NMX4]−, [Cu(bipy)2X]+, [Cu(phen)2X]+, [M(dppe)2X], [M(tripod)X], [M(terpy)X2], [M(NO)L4] with the {MNO}8 electron count, vanadium-(IV) and -(V) compounds including several oxides and vanadyl complexes. The SN2 substitution pathway in Sn compounds that had been previously shown to be well represented by the structural data of a series of compounds with, e.g., a XSnC3O core are also shown to be elegantly described by the simultaneous change in their TBP and Td continuous symmetry measures.

Continuous symmetry measures of penta-coordinate molecules: Berry and non-Berry distortions of the trigonal bipyramid

The copper(II) complexes of the Schiff-base ligands H 2 Sams and H 2 Saes and the reduced Schiff-base ligands H 2 Sam and H 2 Sae formed between salicylaldehyde and aminomethanesulfonic acid or 2-aminoethanesulfonic acid (taurine) have been synthesized in moderate yields. The solid-state structures of the five dinuclear complexes, [Cu 2 (Sams) 2 (H 2 O 2 ] (1), [Cu 2 (Sam) 2 (H 2 O) 2 ].H 2 O (2), [Cu 2 (Saes) 2 (H 2 O) 2 ].2H 2 O (3), [Cu 2 (Sae) 2 ].2H 2 O (4), and [Cu 2 (Sae) 2 (DMF) 2 ].2DMF (5), have been determined by X-ray crystallography, showing that the Cu I I centers have distorted square-pyramidal geometry. The Schiff-base copper complexes 1 and 3 have hydrogen-bonded 2D sheet structures while the reduced Schiff-base complexes 4 and 5 display a 2D coordination network and a hydrogen-bonded 2D structure respectively. All these complexes have been investigated for their catecholase activity and activity measurements have been compared with those of dinuclear copper(II) complexes of similar ligands obtained with carboxylate analogues of the corresponding sulfonic acids; these studies show that 4 has significantly higher activity. Further, a strong antiferromagnetic interaction between Cu I I ions in dimeric complexes 1 [J = -9.04(2) cm - 1 ], 3 [J = -272(4) cm - 1 ), and 4 [J = -237(4) cm - 1 ] has been observed.

Copper(II) Complexes of Schiff-Base and Reduced Schiff-Base Ligands: Influence of Weakly Coordinating Sulfonate Groups on the Structure and Oxidation of 3,5-DTBC

Two highly charged cationic copper(II) complexes have been synthesized and characterized structurally and spectroscopically: [Cu(L1)2(Br)](ClO4)5 (1) and [Cu(L2)2(Br)](ClO4)5 (2) (L1 = 5,5′-di(1-(triethylammonio)methyl)-2,2′-dipyridyl cation and L2 = 5,5′-di(1-(tributylammonio)methyl)-2,2′-dipyridyl cation bidentate ligands). X-Ray structures show that Cu(II) ions in both complexes have a trigonal-bipyramidal CuN4Br-configuration. Two nitrogen atoms of the electropositive pendants and coordinated bromine atom basically array in a straight line. Their close distances of N⋯Br atoms are 5.772 and 5.594 A, respectively, which is comparable to that of adjacent phosphodiesters in B-form DNA (ca. 6 A). In the absence of reducing agent, supercoiled plasmid DNA cleavage by the complexes has been performed and their hydrolytic mechanisms have been investigated. The pseudo-Michaelis–Menten kinetic parameters (kcat), 4.15 h−1 for 1, 0.43 h−1 for 2 and 0.61 h−1 for [Cu(bipy)(NO3)2], were obtained. This result indicates that 1 exhibits markedly higher nuclease activity than its corresponding analogues. The high ability of DNA cleavage for 1 is attributed to the effective cooperation of the metal moiety and two positive pendants since the array of linear tri-binding sites matches with one of three phosphodiester backbones of nucleic acid.

Double-strand DNA cleavage by copper complexes of 2,2'-dipyridyl with electropositive pendants.

The crystal structures of [Cu(phen)2Br][Br]·H2O (1, phen = 1,10-phenanthroline), [Cu(phen)2Br][ClO4] (2), [Cu(phen)2Br][NO3]·H2O (3), [Cu(phen)2Br][PF6] (4), and [Cu(phen)2Br][BPh4] (5) have been determined by X-ray diffraction. Four of the complexes, 1−4, have a CuN4Br chromophore with a square based pyramidal distorted trigonal bipyramidal (SBPDTB) stereochemistry, while 5 involves an extreme trigonal bipyramidal distorted square based pyramidal (TBDSBP) stereochemistry. The geometries of the CuN4Br chromophores in 1−5 are compared by scatter plot analysis with a single [Cu(phen)2Br][ClO4] complex, 6, of known crystal structure involving a crystallographic 2-fold axis of symmetry. The distortion isomers of 2 and 6 are significantly different. The scatter plots of the six cation distortion isomers of the [Cu(phen)2Br][Y] series of complexes suggest that all six complexes lie on a common structural pathway, involving a mixture of the symmetric, νsym, C2 mode and the asymmetric, νasym, non-C2 mode of vibra...

Comparative Crystallography. 5. Crystal Structures, Electronic Properties, and Structural Pathways of Five [Cu(phen)2Br][Y] Complexes, Y = [Br]-·H2O, [ClO4]-, [NO3]-·H2O, [PF6]-, and [BPh4]-

The range in static stereochemistry of the cation distortion isomers of the [Cu (chelate)2Cl]+ cation, where chelate=bipy, phen or bipyam. The low temperature crystal structure (150 K) of [Cu (bipy)2Cl] [PF6]·H2O and [Cu (phen)2Cl] [BPh4]

The crystal structures of ten distortion isomers of the [Cu(bipy)2X]+ cation have been determined, where X = Cl– (2), Br– (5) or I– (3), and compared by scatter plot analysis with twenty [Cu(bipy)2X]Y complexes of known crystal structure In the ten new structures two involve a near regular trigonal bipyramidal stereochemistry (τ = 094–090) and eight show a square based pyramidal distorted trigonal bipyramidal stereochemistry (τ = 089–049), where τ = (α8 – α1)/60 [where α1 = N(2)–Cu–Cl, α8 = N(1)–Cu–N(3)] Scatter plots of the eighteen cation distortion isomers of the [Cu(bipy)2Cl][Y] series of complexes suggest that all eighteen complexes lie on a common structural pathway, involving a mixture of the symmetric, C2, and the asymmetric, non-C2, in-plane modes of vibration of the CuN4Cl chromophore The resulting structural pathways are consistent with the direct observation of the effect of the modes of vibration on the stereochemistries of the complexes A comparison of the trends in the bipy/Cl, Br and I data suggests a size effect of the Br– and I– ligands

Crystal structures, electronic properties and structural pathways of thirty [Cu(bipy)2X][Y] complexes, where X = Cl–, Br– or I–†

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Comparative Crystallography. 5. Crystal Structures, Electronic Properties, and Structural Pathways of Five [Cu(phen)2Br][Y] Complexes, Y = [Br]-·H2O, [ClO4]-, [NO3]-·H2O, [PF6]-, and [BPh4]-

The range in static stereochemistry of the cation distortion isomers of the [Cu (chelate)2Cl]+ cation, where chelate=bipy, phen or bipyam. The low temperature crystal structure (150 K) of [Cu (bipy)2Cl] [PF6]·H2O and [Cu (phen)2Cl] [BPh4]

Crystal structures, electronic properties and structural pathways of thirty [Cu(bipy)2X][Y] complexes, where X = Cl–, Br– or I–†