Rolf Uggla

Comparison of the structural parameters in copper(II) acetate-type dimers containing distorted square pyramidal CuO4O and CuO4N chromophores

Abstract A survey of 123 of copper(II) acetate-type dimeric complex units, determined by X-ray diffraction in the crystal structures containing either a CuO 4 O or CuO 4 N chromophore, gave the following results. All the distorted square pyramidal coordination spheres contain a copper atom displaced 0.165–0.225 and 0.184–0.322 A from the basal O 4 plane in CuO 4 O and CuO 4 N chromophores, respectively. The Cu-Cu distances were in the range of 2.575–2.702 and 2.603–2.886 A for the CuO 4 O and CuO 4 N chromophores, respectively. The apical ligand atoms show large coefficients of variation for the distortion from the perpendicular to the basal O 4 plane. There is highly significant propensity for the copper(II) atoms to move out from the basal O 4 plane upon elongation of the Cu-Cu distance. Strong negative correlations were found between the CuOC and OCO angles. The most marked deviations for the observed parameters are caused by the bridges containing a halogenoacetate anion, leading to distorted trigonal bipyramidal geometry.

Conformational flexibility of the di(1,3-diaminopropane)copper(II) cation Part 3. Structure determination for trans-diaquabis(1,3-diaminopropane-N,N′)copper(II)trans-di(ortho-phthalato-O)bis(1,3-diaminopropane-N,N′)cuprate(II) monohydrate and DFT calculations for the trans-diaquabis(1,3-diaminopropane-N,N′)copper(II) cation2

Abstract The structure of trans-diaquabis(1,3-diaminopropane-N,N′)copper(II)trans-di(ortho-phthalato-O)bis(1,3-diaminopropane-N,N′)-cuprate(II) dihydrate was determined by single crystal X-ray diffraction methods. The compound crystallises in the triclinic system, space group P 1 (No. 2) with a = 7.233(2), b = 10.187(2), c = 12.905(2) A , α = 81.70(2), β = 82.08(2) and γ = 81.03(2)°, and V = 922.8(3) A 3 . The structure consists of cationic and anionic monomeric coordination units and a crystal water molecule. Both of the coordination units contain a centrosymmetric [Cu(tn)2]2γ moiety (tn = 1,3-diaminopropane). In the cationic unit the axial sites are occupied by water molecules, whereas in the anionic unit there are doubly deprotonated ortho-phthalate anions in the axial positions. The respective CuO bond lengths are quite long, 2.618(2) and 2.622(2) A. The six-membered chelate rings formed by the CuII ion and in display a chair conformation. In the anionic complex unit the rings are less puckered. The geometry of the cationic species was optimised by DFT methods and it was found to be more stable than a five-coordinated species with a non-coordinated water by 77.4 kJ mol−1.

Unexpected five-coordination in di(1,3-diaminopropane)-3,5-dinitrobenzoatocopper(II) 3,5-dinitrobenzoate. Comparison between the coordinated and non-coordinated anions

Abstract The crystal and molecular structure of di(1,3-diaminopropane)-3,5-dinitrobenzoatocopper(II) 3,5-dinitrobenzoate (C 13 H 23 CuN 6 O 6 ) + (C 7 H 3 N 2 O 6 ) − was determined by single crystal X-ray methods. The compound crystallizes in the monoclinic system, space group P 2 1 / c , a =19.378(9), b =6.358(2), c =22.549(9) A, β=107.48(3)°, Z =4, D c =1.59, D m =1.60(1) g/cm 3 . The final R value for 2746 reflections was 0.037 ( R w =0.035, 1/σ 2 weights). Only one of the two 3,5-dinitrobenzoate anions is coordinated via one carboxylate oxygen with the bond length of 2.252(3) A. Thus the coordination around the central Cu II ion is 4 + 1 and the site symmetry approximately C 2v . The coordination mode 4+1 is the first reported among the series consisting of variously substituted benzoates and bis(1,3- diaminopropane)copper(II) cations. The non-coordinated 3,5-dinitrobenzoate anion is bonded by hydrogen bonds to the neighbouring amines. The v as (CO 2 ) vibrations for both anions appear at about 1609 cm −1 , whereas the v s (CO 2 ) is seen at 1335 and 1527 cm −1 for the coordinated and non-coordinated anions, respectively. Ab initio calculations with the 3-21G* basis set for 3,5-dinitrobenzoic acid and its anion reveal elongation of the bond between the carboxylate group and aromatic ring upon deprotonation of the acid. The complexation of the anion does not cause any clear difference in the bond length. The charge densities obtained by the STO-3G* basis set show that the oxygen coordinated to the copper(II) cation carries more negative charge than the non- coordinated oxygen. In the non-coordinated anion the charge densities are more evenly distributed.

A new class of oxazaborolidine derivatives discovered. Ketones and aldehydes as bidentate ligands

Abstract Novel adducts ( 5′a-f ) of H 2 CO Me 2 CO and H 2 BOR (R = H, Me) to aminoborane ( 1′a ), aminohydroxy-borane ( 1′b ) and 1,3,2-oxazaborolidine ( 1′c ) were studied by means of ab initio MO (RHF) methods. Energies of the formation of the adducts were clearly exothermic [e.g. −140 and −134 kJ mol −1 (MP2/6–31G∗MP2/6–31G∗) in the case of H 2 CO - H 2 BOH adduct of 1′a and 1′c ]. All the Me 2 CO adducts were found to be slightly less stable than the corresponding H 2 CO adducts. In all the adducts ( 5′a-f ) studied the carbonyl system was found to behave as a bidentate ligand. All the bidentate adducts were found to be significantly more stable than the related monodentate adducts ( 4′a-c ). Activation of the carbonyl moiety of the bidentate adducts resembles that of the related adducts of N -sulfonylated oxazaborolidines ( 7 ).

Conformational isomerism and effect of complexation on carboxylate group in two crystallographically independent coordination units of trans-di(4-chlorobenzoato-O)bis(1,3-diaminopropane-N,N′)cobalt(III) 4-chlorobenzoate dihydrate

The crystal and molecular structure of the title compound was determined by single crystal X-ray methods. The compound crystallises in the triclinic system, space group P1 (No. 2, a=10.477(3), b=12.309(2), c=13.420(3() A, α=85.40(2), β=78.39(2), γ=71.46(2)°, Z=2, Dc=1.47, Dm-1.46(10 g cm−3. The final R value for 4415 reflections was 0.038 (Rw=0.033, 1/σ2 weoghts). The structure consists of two crystallographically independent complex units, a non-coordinated 4-chlorobenzoate anion and two crystal water molecules. Both complex units possess similar Ci symmetry with 1,3-diaminopropane ligands forming chelate rings and the axial sites occupied by 4-chlorobenzoate anions. The central low-spin cobalt cations have the oxidation state +3. The CoN distances are in the range 1.963(2)–1.972(2) A. The main differences in the two complex units are seen in the axial bond lengths and bite angles. In the complex unit a the axial bond length is 1.926(2) A and the total puckering of the chelate ring is 0.510 A, whereas in the unit b the corresponding values are 1.909(2) and 0.585 A. The corresponding N1CoN2 bite angles are 93.03(9) and 88.76(9)°. The two conformational isomers arise from differences in hydrogen bonding and stacking of the benzoate anions. Ab initio calculations with the 6–31G∗ basis set for 4-chlorobenzoic acid and its anion reveal elongation of the bond between the carboxylate group and aromatic ring upon deprotonation of the acid. The complexation of the anion results in elongation in the corresponding O(coordinated)-C bond. There is strong correlation between the axial bond length MO and the angle O(non-coordinated)-C(carboxylate)-C(aromatic) in the structures containing a fragment similar to the title compound. The charge densities obtained by the STO-3G∗ basis set show that the oxygen coordinated anion the charge cobalt(III) cation carries more negative charge than the non-coordinated oxygen. In the non-coordinated anion the charge densities are more evenly distributed.

Effect of hydrogen bonding on the coordination: Part 2. Semi-coordination in trans-di(salicylato)bis(1,3-diaminopropane-N,N’)copper(II)

Abstract The crystal and molecular structure of trans-di(ortho-hydroxobenzoato-O)bis(1,3-diaminopropane-N,N′)copper(II) [ortho-hydroxobenzoate=salicylate hereafter] determined by single crystal X-ray diffraction methods at T=193(2) K. The structure is composed of monomeric complex units with the central copper(II) ion occupying a centre of symmetry. The coordination polyhedron can be described as axially elongated distorted octahedron with the axial Cu–O bond length of 2.559(3) A indicating semi-coordination. There is notable asymmetry in the coordinated 1,3-diaminopropane molecule, which forms a six-membered chelate ring displaying Cu–N1–C1 and Cu–N2–C3 angles of 121.5(2) and 117.4(2)°, respectively. This deviation may be correlated to differences in hydrogen bonding between the amino groups and the non-coordinated oxygen atoms of the salicylate anions. The coordinated salicylate anion shows considerable declination of 28.9°, which may be correlated to intramolecular hydrogen bonding. The electronic properties of benzoate anions were studied by Natural Bond Order (NBO) analyses for optimised model compounds at the MP2/6-311+G*//MP2/6-311+G* level of theory. The results suggest that semi-coordination is mainly characterised by concomitant electrostatic attraction of the charges at the central copper(II) cation and repulsion between an electron lone pair of a ligand atom and the electron lone pair at the copper(II) 3dz2 atomic orbital.

Conformational flexibility of the di (1,3-diaminopropane)- copper (II) cation Part 2. Structure determination for aqua-di(1,3-diaminopropane-N,N′)-copper (II) dichloride and chlorodi (1,3-diaminopropane-N,N'⊃-copper(II) chloride methanol solvate and DF17 calculations for aqua-di (1,3-diaminopropane-N,N′) copper (II) cation

The structures of aqua-di(1,3-diaminopropane-N,N′)copper (II) dichloride (1) and chloro-di(1,3-diaminopropane-N N′) copper (II) chloride methanol solvate (2) were determined by single crystal X-ray methods. [Cu(tn)2H2O]Cl2 (1) (tn=1,3-diaminopropane), C6H22Cl2CuN4O, Mr = 300.72, tetragonal, space group P42nm (No. 102), a = 9.3146 (5) , c = 7.591(1) A, V = 658.63(9) A3, Z = 2, Dc = 1.516 g cm−3. [Cu(tn)2Cl]Cl·MeOH (2), C7H24Cl2CuN4O, Mr = 314.74, monoclinic, space group P21/c (No. 14), a = 8.598 (2) , b =16.176 (2) , c = 10.418(4) A, β = 107.11(3)°, V = 1384.7(7) A3, Z = 4, Dc = 1.510 g cm−3. Compound 1 is formed in aqueous solution, whereas 2 was obtained in methanol. The coordination polyhedron in 1 is square pyramid with exceptionally high site symmetry of 4mm (C4v) around the copper(II) cation. The distances from the central copper(II) cation to the two nearest chloride ions are different in 2, 2.736(2) and 3.322(2) A. If the remote chloride is not taken into consideration, the coordination polyhedron could be described as distorted square pyramid. In both compounds the chelate rings display chair conformation. In 1 the two to ligands are coordinated to copper in syn-like fashion, whereas in 2 the rings are in normal anti-like conformation. The rare syn-like conformation is a stable conformation, since the overall geometry was not changed during optimization carried out at the LDA/DNP level of theory. The optimized syn-like conformation is favoured by 16.38 kJ mol−1 over the optimized anti-like conformation of the [Cu(tn)2(H2O)]2+ cation.

On the role of π-stacking in aldehyde complexes of N-sulphonylated oxazaborolidinones used as chiral catalysts

Aldehyde complexes of Lewis acidic chiral N-sulphonylated oxazaborolidinones (e.g. 1) were studied by means of density functional methods at the JMW/DNP level. As a model of such complexes was chosen the acrolein N-phenylsulphonyl-1,3,2-oxazaborolidin-5-one adduct 2a. Compared with the related adducts of the parent oxazaborolidinone (2b; the phenyl of 2a replaced by hydrogen) the bidentate bonding of acrolein was found to be significantly dependent on the presence of the phenyl group. As the group was replaced by hydrogen the Oso2 - Cco bond lengthened substantially (by 0.225 A) upon optimization. Distances between the vinyl and phenyl moieties were in the range of 3.7 – 4.0 A in the complex 2a suggest π-stacking. Almost equal energies of the formation of 2a and 2b imply the stacking to be passive in nature. Results of the Natural Bond Order analysis of 2a support passive π-stacking; significant attractive interactions between the vinyl and phenyl groups of 2a were not found.

Influence of secondary bonding on the intradimer distance of trichloro(ethane-1,2-diolato-O,O′)tellurate(IV)

The structure of ammonium trichloro(ethane-1,2-diolato-O,O′)tellurate(IV) was determined by single-crystal methods: monoclinic, space group P21/c(no. 14), a= 10.779(1 ), b= 12.418(2), c= 6.915(1)A, β= 108.65(1)°. The co-ordination around TeIV is distorted ψ octahedral with one of the two oxygen atoms lying opposite to the lone pair of Te. Two identical anions form a dimeric unit via a centre of symmetry. A short Te–O intradimeric distance of 2.764(6)A is about 0.84 A shorter than the sum of the corresponding van der Waals radii. The structure is compared with that of the corresponding tetraphenylphosphonium salt where the intradimer distance is clearly longer. The size of the cation and the amount of intermolecular interactions seem to be decisive factors in secondary bonding between two anionic units. The electronic properties of the anions in the two salts were investigated by ab initiocalculations and compared with those of the optimised structure of the corresponding monomeric anion. The positive charge of 1.36 electrons at Te is almost invariable. The main interaction within a dimeric unit in the ammonium salt is a donation of an electron pair from oxygen to the antibonding molecular orbital between Te–Cl in the neighbouring anion. The bond between Te and one of the equatorial Cl atoms (opposite to oxygen) is sensitive to dimerisation. The charge density, ionic nature of the bond and bond length increase when the degree of dimerisation increases, whereas the other two Te–Cl bonds are almost insensitive.

STEREOSPECIFIC SYNTHESIS AND CRYSTAL STRUCTURE OF THE RACEMATE OF 1-THIA-2-TELLURA-1(1-ALLYL-4-CHLORO)CYCLOPENTANE 2,2,2-TRICHLORIDE

Abstract Tellurium tetrachloride and diallyl sulfide react to stereospecifically formed crystals of 1-thia-2-tellura-1(1-allyl-4-chloro)cyclopentane 2,2,2-trichloride. According to single-crystal X-ray determination the structure consists of the (R,R)-(S,S) racemate unit with a centre of symmetry. In the asymmetric units the TeIV-atoms display distorted ψ octahedral coordination. Although the equatorial Te-S bond length is 2.763(1) A, the Natural Bond Order (NBO) analysis reveals significant electronic interaction.