Mario Calligaris

Structure and bonding in metal sulfoxide complexes

Abstract Structural parameters of free and coordinated sulfoxides are comprehensively reviewed and average values derived. Principal component analyses have been performed in order to evidence the deformation pathways of sulfoxides upon coordination. Electronic and steric factors affecting the bonding mode of sulfoxides are discussed.

Synthesis and characterization of two new classes of ruthenium(III)-sulfoxide complexes with nitrogen donor ligands (L): Na[trans-RuCl4(R2SO)(L)] and mer, cis-RuCl3(R2SO)(R2SO)(L). The crystal structure of Na[trans-RuCl4(DMSO)(NH3)] · 2DMSO, Na[trans-RuCl4(DMSO)(Im)] · H2O, Me2CO (Im = imidazole) and mer, cis-RuCl3(DMSO)(DMSO)(NH3)

Abstract In this paper we report the synthesis of two new classes of chloride-sulfoxide-Ru(III) derivatives containing a nitrogen ligand (L) of general formula: Na[trans-RuCl4(R2SO)(L)] and mer, cis-RuCl3(R2SO)(R2SO)(L). Their spectroscopic characterization in the solid state (IR) and in solution (NMR, UVVis) is also described. The cyclic voltammetry of the complexes performed in aqueous solution shows in every case a monoelectronic and rather rapid Ru(III)/Ru(II) electron transfer. The observed formal potentials are much more positive than those reported for other Ru(III) complexes. The net charge, together with the, π acidic ability of DMSO, are the factors responsible for this behaviour. The crystal structures of Na[trans-RuCl4(DMSO)(NH3)] · 2DMSO (5a), Na[trans-RuCl4(DMSO)(Im)] · H2O, Me2CO 5b and mer, cis-RuCl3(DMSO)(DMSO)(NH3) (6a) have been determined by three dimensional X-ray analyses. Crystal data are: a = 9.578(2), b = 12.480(2), c = 9.594(6) A, α = 104.33(3), β = 119.04(2), γ = 80.71(3)°, triclinic, space group P 1 , Z = 2 for 5a; a = 10.790(4), b = 11.411(4), c = 7.658(4) A, α = 105.92(3), β =93.61(1), γ = 83.50(3)°, triclinic, space group P 1 , Z = 2 for 5b; a = 10.110(3), b = 9.718(3), c = 14.101(3) A, β = 108.89(3)°, monoclinic, space group P21/n, Z = 4 for 6a. Least-squares refinement based on 4897 5a, 4932 5b and 3152 6a independent reflections converged to R = 0.039, 0.031 and 0.022, respectively. In 5a and 5b, the DMSO ligand is S-bonded to Ru, with RuS bond distances (trans to N) of 2.2797(7) and 2.2956(6) A, respectively, while in 6a, one DMSO, trans to N, is S-bonded (RuS, 2.2714(6) A), and the other, trans to Cl, is O-bonded (RuO, 2.070(2) A). The RuCl bond distance, trans to O, is 2.3207(7) A. The RuCl bond distances, trans to Cl, are similar in all three compounds averaging 2.343(6) A. Relevance in the synthesis of the new derivatives comes from the known antitumor properties of isostructural Ru(III) complexes with heterocyclic nitrogen ligands. The antitumor activity of some of the new compounds are currently under investigation. Their redox potentials suggest the possibility that they might undergo an easy biological reduction in vivo.

Cation‐site location in a natural chabazite

(Ca,Sr) chabazite, Cal.aSro.3A13.sSis.3024.13H20 from electron microprobe analysis, rhombohedral, R3m, a = 9.421(4)A, a = 94.20(1) °, U = 829 A 3, Z = 1, g(Mo Ka) = 0.82 mm-~; final R = 0.071 for 578 independent reflections. The location of three cation sites along the [ 1111 direction and of water molecules in the zeolitic cage is discussed and compared with that previously attributed on the basis of a two-dimensional analysis. Introduction. Chabazite is a natural zeolite of group 4, its framework being built up by double six-membered rings (D6R), linked by tilted four-membered rings (Fig. 1). The framework contains large ellipsoidal cavities of 6.7 x 10 A, entered by eight-membered rings (Breck, 1974). The ion-exchange properties and the role played by exchangeable cations in molecule-sieving properties justify the interest for a structural study of chabazites (Mortier, Pluth & Smith, 1977a,b; Pluth, Smith & Mortier, 1977; Barrer, 1978). On the other hand only two-dimensional X-ray diffraction analyses have been reported for hydrated natural chabazites (Smith, Rinaldi & Dent Glasser, 1963; Smith, Knowles & Rinaldi, 1964). From these results it was suggested that cations occupy but one site at x = 0.357, y = 0.494, z = 0.577, so that the crystal should contain two calcium ions and 13 water molecules per unit cell. To verify such an arrangement of cations and water molecules, we have undertaken the three-dimensional 0567-7408/82/020602-04501.00 X-ray analysis of a natural chabazite as the first step of a structural study of chabazites exchanged with transition-metal ions. The natural sample was from north-east Azerbaijan, Iran (Comin-Chiaramonti, Pongiluppi & Vezzalini, 1979). Wavelength dispersive microprobe analysis was carried out on eight single crystals of chabazite, using a fully automated ARLSEMQ instrument. The mean chemical analysis and the atomic ratios evaluated for 24 O atoms are given in Table 1. The chemical analysis indicates that the chabazite is particularly rich in strontium.

Ruthenium(II)-dimethyl sulfoxide complexes with nitrogen ligands: synthesis, characterization and solution chemistry. The crystal structures of cis,fac-RuCl2(DMSO)3(NH3) and trans,cis,cis-RuCl2(DMSO)2(NH3)2·H2O

Abstract In this paper we report the synthesis and characterization of some new derivatives of the isomers cis- (1) and trans-RuCl2(DMSO)4 (6) (DMSO=dimethyl sulfoxide) with monodentate nitrogen donor ligands (L) such as NH3, imidazole (Im) and benzimidazole (BzIm): cis,fac,-RuCl2(DMSO)3(L) (L=NH3 (2) Im (3)); cis,cis,cis-RuCl2(DMSO)2(Im)2 (4); fac-[Ru(Im)3Cl(DMSO)2]PF6 (5); trans,cis,cis-RuCl2(DMSO)2(L)2 (L=NH3 (7), Im (8), BzIm (9)); trans,-RuCl2(DMSO)3(Im) (10). All complexes have exclusively S-bonded DMSOs. Their chemical behavior in aqueous solution is also described. The crystal structures of cis,fac-RuCl2(DMSO)3(NH3) (2) and trans,cis,cis-RuCl2(DMSO)2(NH3)2·H2O (7) were determined by three dimensional X-ray analyses. Crystal data: 2, a=9.103(2), b=12.568(2), c=13.375(6) A, β=96.52(2)°, monoclinic, space group P21/n, Z=4; 7, a=8.507(4), b=11.331(4), c=14.071(4) A, β=90.99(1)°, monoclinic, space group P21c, Z=4. Least-squares refinement based on 4045 (2) and 3682 (7) reflections converged to R=0.026 and 0.030 for 2 and 7, respectively. In 2, the three DMSOs have RuS bond distances of 2.2774(6) and 2.2458(5) A (trans to Cl), and 2.2877(5) A (trans to N). The RuCl bond distances are 2.4178(6) and 2.4411(6) A (trans to S), while the RuN (trans to S) bond length is 2.151(2) A. In 7, the trans RuCl bond distances are 2.4030(7) and 2.4125(7) A, while the RuS (trans to N) bond distances are 2.2350(6) and 2.2469(6) A, and the RuN (trans to S) 2.142(2) and 2.156(2) A.

Synthesis and characterization of new halogen-tetramethylene sulfoxide-ruthenium(II) and ruthenium(III) complexes; crystal structure of cis-dichlorotetrakis(tetramethylene sulfoxide)ruthenium(II) and hydrogen trans-bis(tetramethylene sulfoxide)tetrachlororuthenate(III)

In this paper we report the synthesis and characterization of the following ruthenium(II) and ruthenium(III) complexes with tetramethylene sulfoxide (TMSO): cis-RuCl2(TMSO)4 (1), trans- RuCl2(TMSO)4 (2), the corresponding dibromo derivatives cis- and trans-RuBr2(TMSO)4 (3 and 4, respectively), (TMSO)H[trans-Ru(TMSO)2Cl4] (5) and mer-RuCl3(TMSO)3 (6). Most of the reported complexes are described here for the first time, together with a new, easy synthetic path for the previously known complexes 1 and 3. The chemical behavior of 1 and 2 in solution of aprotic, non- coordinating solvents is described. Among the Ru(II) derivatives, the cis isomers are thermodynamically more stable and a photochemically driven cis to trans isomerization reaction is observed in tetramethylene sulfoxide solution. We also report the crystal structures of cis-RuCl2(TMSO)4 (1) and (TMSO)H[trans- Ru(TMSO)2Cl4] (5), as determined by three dimensional X-ray analyses. Crystal data: 1, a=9.104(2), b=11.317(2), c=21.867(6) A, β=90.62(2)°, monoclinic, space group P21/c, Z=4; 5, a=14.642(4), b=14.999(4), c=9.667(4) A, β=103.57(1)°, monoclinic, space group P1/c, Z=4. Least-squares refinement based on 3813 (1) and 4706 (5) reflections converged to R=0.032 and 0.033 for 1 and 5, respectively. In 1, all the TMSO ligands are S-bonded to Ru, with average RuS bond distances of 2.355(6) (trans to S) and 2.273(1) (trans to Cl) A. The TMSO ligands in 5 are both S-bonded to Ru (av. 2.33(1) A). The protonated TMSO molecule is hydrogen bonded to one of the two crystallographically independent anions.

Synthesis and characterization of palladium(II)-η3-allyl–ylide complexes. X-Ray crystal structure of [PdCl(η3-2-MeC3H4){Ph3PC(H)COMe}]

The complexes [PdCl(η3-2-XC3H4){Ph3PC(H)COR}][R = Me, X = H (1) or Me(2); R = Ph, X = H (3) or Me (4)] have been obtained in high yields by treatment of the dimers [{PdCl(η3-2-XC3H4)}2] with the keto-stabilized ylides Ph3PC(H)COMe [ampp, (acetylmethylene)triphenylphosphorane] and Ph3PC(H)COPh [bmpp, (benzoylmethylene)triphenylphosphorane] in CH2Cl2 solution. They have been characterized by analytical data, i.r., low-temperature 1H and 31P-{1H} n.m.r., and for complex (2) also by 13C n.m.r. spectroscopy. Spectroscopic evidence indicates that complexes (1)–(4) in solution at low temperature are present as two diastereoisomeric forms arising from co-ordination on the metal centre of the asymmetric ylidic carbon atom and of the η3-allyl ligand. In CH2Cl2 solution at room temperature the complexes are in equilibrium with their reagents. Reaction with PPh3 and [AsPh4]Cl gives [ PdCl(η3-2-XC3H4)(PPh3)] and [AsPh4][PdCl2-(η3-2-XC3H4)], respectively, and the free ylide. The X-ray crystal structure of complex (2) was determined showing that, in the solid state, only one diastereoisomer is present. The crystals are monoclinic, space group P21/n with a= 9.668(3), b= 14.879(4), c= 16.226(3)A, β= 99.85(2)°, and Z= 4. Final full-matrix least-squares refinement, based on 3 063 reflections, converged to R= 0.031. The keto-stabilized ylide ligand is C bonded to the metal with a Pd–C distance of 2.193(3)A.

Structural effects of the co-ordination of quadridentate Schiff bases to transition-metal atoms. Structure of NN′-(o-phenylene)bis(salicylideneamine) and of its cobalt(II) complex

Geometrical variations which occur when a quadridentate Schiff-base co-ordinates to a cobalt(II) atom are compared on the basis of the crystal structure analysis of the ligand NN′-(o-phenylene) bis(salicylideneamine)(I) and its CoII derivative in its orthorhombic (II) and monoclinic (III) modifications. Crystals of (I) are monoclinic, space group P21/c, with cell parameters: a= 6.064(3), b= 16.541(7), c= 13.306(7)A, β= 91.5(1)°. Crystals of (II) are orthorhombic, space group P212121, with a= 16.755(7), b= 17.532(8), c= 5.362(3)A, and of (III) are monoclinic, space group P21/nwith a= 10.681(5), b= 8.354(4), c= 18.185(8)A, β= 105.3(1)°. A total of 1 277 (I). 1 113 (II), and 2 558 (III) independent reflexions were used : the structures were solved from diffractometer data by the heavy-atom method and refined to final R factors of 0.056 (I), 0.046 (II), and 0.041 (III). The enolimine form is established for (I) in the solid state. Upon co-ordination, with formation of (II) and (III), the geometrical data suggest that the contribution to the resonance of a ketamine form becomes as important as that of the enolimine. This is in agreementwith a π-orbital delocalization of the electronic charge over the planar complex molecule.

The crystal and molecular structure of N,N′-ethylene- bis-(acetylacetoneiminato)methylcobalt(III)

Abstract The crystal structure of N,N′ethylene-bis-(acetylacetoneiminato)methyl-cobalt(III), CoO2N2C13H23 has been determined by the heavy atom method and refined to a conventional R-value of 0.090 by the least-squares method using three-dimensional data. The crystals are orthorhombic, space group P212121, with four molecules in the unit cell of dimensions a=5.99±0.01 A, b=13.02±0.02 A, c=17.69±0.03 A. The measured and calculated densities were 1.44 and 1.43 g. cm−3, respectively. The crystal consist of monomeric molecules with a five-coordinate stereochemistry. The nearly planar tetradentate ligand occupies the four basal positions of a distorted rectangular-based pyramid, whose axial position is occupied by the methyl group. The bond lengths are 1.87±0.01 A (mean) for CoO, 1.87±0.01 A (mean) for CoN, 1.95±0.02 A for CoCH3.

Cation site location in hydrated chabazites. Crystal structure of barium- and cadmium- exchanged chabazites

Chabazite from N.E. Azerbaijan, Iran, was ion-exchanged with barium and cadmium to give Ba 1.8 Al 3.8 Si 8.2 O 24 , 9.7 H 2 O and Ca 0.31 Sr 0.13 Cd 1.4 Al 3.8 Si 8.2 O 24 , 11.6 H 2 O respectively. Both structures were determined at room temperature in the R3m space group with cell dimensions a = 9.420(9) A, α = 94.21(7)° and a = 9.435(9) A, α = 94.66(6)° for the Ba- and Cd-exchanged chabazites. The final R index is 0.097 for (Ba-chab and 0.072 for (Cd)-chab using 685 and 555 independent reflections respectively in the least squares refinement. Comparison of the electron distribution in the cages after ion-exchange with that of the parent chabazite indicates the presence of three chief cation sites: two in the large cage alone the [1 1 1] diagonal and one located near the 8-ring window. The site at the centre of the hexagonal prism, present in the natural chabazite, is not occupied since it may only accommodate small ions such as calcium.

Crystal structures of the hydrated and dehydrated forms of a partially cesium-exchanged chabazite

Crystal structures of a partially cesium-exchanged chabazite h-Cs-CHA, Cs 3.0 Ca 0.4 Al 3.8 Si 8.3 O 24 .9.5H 2 O and its dehydrated form d-Cs-CHA were determined in the rhombohedral space group R ¯3 m . Unit cell parameters and R -indexes were a =9.441 (1)A, α=94.23(2)° and 0.049 for h-Cs-CHA, and a =9.397(2)A, α=93.74(2)° and 0.046 for d-Cs-CHA, respectively. In both h-Cs-CHA and d-Cs-CHA, site IV, at the centre of the S 8 R window, is nearly fully occupied by the Cs + ions. In h-Cs-CHA, a small number of Cs + ions are located in site 1′, along the [111] direction. The Ca 2+ ions occupy site 1″, along the [111] direction, in h-Cs-CHA and site III, at the centre of the D 6 R cage, in d-Cs-CHA. Only minor distortions of the framework geometry occur upon dehydration, in contrast with the results found for chabazites exchanged with other monovalent cations. The framework stability is discussed and related to the dimensions of the Cs + ion.