Anna Maria Manotti Lanfredi

Increase in coordination number of lanthanide complexes with 2,2′-bipyridine and 1,10-phenanthroline by using β-diketonates with electron-withdrawing groups

Abstract The coordination chemistry of Ln(hfpd)3 (hfpd=1,1,1,5,5,5-hexafluoropentane-2,4-dionate) with phen and bpy depends on the size of the Ln3+ ion and on the used solvent. The complexes [Er(hfpd)3(phen)] (7) and [Er(hfpd)3(bpy)] (14) were obtained from the synthesis of Er(CF3SO3)3 with Hhfpd, CsOH and either 1,10-phenanthroline or 2,2′-bipyridine in acetonitrile. The structure of 7 was determined by X-ray crystallography. Similar reactions, but performed in methanol, with various other lanthanide elements resulted in isolation of five different types of complexes, according to stoichiometry and spectral properties. With elements later in the lanthanide series eight-coordinated complexes of the types [Ln(hfpd)3(bpy)] (for Ln=Dy, Ho and Yb) and [Ln(hfpd)3(phen)] (for Ln=Tb, Ho and Yb), like 7, were obtained, whereas with the early lanthanide elements ten-coordinated complexes of the types [Ln(hfpd)3(bpy)2] (for Ln=La and Sm) and [Ln(hfpd)3(phen)2] (for Ln=La, Ce, Pr and Nd) were isolated. The X-ray crystal structure of [La(hfpd)3(bpy)2] (9) was determined, which provided proof for ten-coordination around the La ion. In addition to [Sm(hfpd)3(bpy)2], the synthesis with Sm and bpy and a trace of water yielded a second compound: the nine-coordinated complex [Sm(hfpd)3(H2O)(bpy)]·(bpy) (11), which was structurally characterised by X-ray crystallography. The LnN distances vary largely, depending on the used N-donor and the Ln3+ ion, and do not run parallel with the Ln3+ ionic radius.

The reactions of ruthenium carbonyl and alkyne-carbonyl complexes with nickelocene, [(η-C5H5)Ni(CO)]2 and (η-C5H5)2Ni2(RC2R′). Cyrstal structures of two isostructural heterometallic trinuclear clusters, (η-C5H5)2Ni2Ru(CO)3(C2Ph2) and (η-C5H5)2Ni2Fe(CO)3(C2Ph2)

The reactions of nickelocene, [(η-C5H5)Ni(CO)]2 and (η-C5H5)2Ni2(RC2R”) (R = H, R′ = But; R = R′ = Et, Ph) with Ru3(CO)12, H4Ru4(CO)12, HRu3(CO)9C2But and HRu3(CO)9(C6H9) are reported and compared with those of the iron carbonyls and alkyne-carbonyls. Some new products have been identified and characterized by spectroscpic analyses. The isostructural trimetallic (η-C5H5)2Ni2Fe(CO)3(C2Ph2) (V) and (η-C5H5)2Ni2Ru(CO)3(C2Ph2) (Va) have been studied by X-ray methods. Crystals of V and Va are monoclinic, space group Cc. Unit cell parameters for V are: a = 9.334(8), b = 26.717(13), c = 9.143(8)A, β = 95.15(7)°, and for Va: a = 9.201(9), b = 27.076(15), c = 9.303(8) A, β = 94.94(7)°. Both structures have been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least squares to R = 0.049 for V and 0.044 for Va. The complexes consist of a triangular cluster formed by two Ni and one Fe atoms and two Ni and one Ru atoms, respectively. A cyclopentadienyl ligand is η-bonded to each Ni atom and three terminal carbonyls are attached to the unique metal atom. The diphenylacetylene, σ-bonded to the Ni atoms and π-bonded to Fe or Ru atom, lies almost parallel to the NiNi side of the cluster. The clusters are considerably smaller in size than other complexes of comparable structure. The elongation of the acetylenic CC bond is different in the two complexes V and Va, although the alkyne—metal interactions are comparable.

Studies on dithio-o-toluate copper(I) complexes with bis(diphenylphosphino)methane. Crystal structures of {di-μ3-dithio-o-toluato-S,S′,S′-bis[μ-bis(diphenylphosphino)methane-μ-dithio-o-toluato-S,S′]} tetracopper(I) and {di[μ-bis(diphenylphosphino)methane]bis(dithio-o-toluato-S,S′)} dicopper(I)

Abstract The structures of [(CuS2CT)2dppm]2 (I) (T = o-tolyl; dppm = bis(diphenylphosphino)methane) and [CuS2CTdppm]2 (II) have been determined by X-ray methods. Crystals of I are monoclinic, space group P21/n, with a = 15.163(4), b = 18.691(5), c = 13.478(4) A, β = 96.81(3)°, Z = 2; crystals of II are orthorhombic. space group Pccn, with a = 23.267(4), b = 13.016(3), c = 20.731(5) A, Z = 4. The structures of I and II have been solved by Patterson and Fourier methods and refined by full-matrix least-squares to R = 0.082 for I and 0.092 for II. The structure of I consists of centrosymmetric tetranuclear complexes in which two pairs of Cu atoms are triply bridged by a dppm ligand and two dithiocarboxylate groups from the dithio-o-toluate ligands. These last behave differently: one of them through a sulphur atom is also bonded to a Cu atom of the other pair so forming a tetranuclear complex. The Cu atoms of each pair show different coordination: Cu(1) displays a distorted trigonal and Cu(2) a distorted trigonal pyramidal geometry. The structure of II consists of dimers, in which each copper atom, doubly bridged by two dppm ligands, completes a distorted trigonal pyramidal coordination through two sulphur atoms from dithio-o-toluate anions acting as chelating ligands. In both compounds the phenyl group of the dithio-o-toluate anions is orthogonal to the corresponding CS2 group. Both complexes give methyldithio-o-toluate in high yields by reaction with methyl iodide.

The synthesis, reactivity and structure of functionally substituted trimetallic clusters of ruthenium

Abstract The reactions of Ru 3 (CO) 12 with terminal acetylenes of the type HCCCRR′X (R = CH 3 R′ = C 2 H 5 , C 6 H 5 , CH 3 , X = OH, Cl, H) were studied. For R = CH 3 , R′ = C 6 H 5 and X = OH good yields of 1 1 trinuclear complexes of the type HRu 3 (CO) 9 (CCCRR′X) (II and III) are obtained, while only small yields of the analogous compounds are obtained with the other acetylenes. Both II and III can be dehydrated at room temperature in the presence of excess trifluoroacetic acid to yield the complexes HRu 3 (CO) 9 [CH 3 (H)CC(CH 3 )C 2 ] (VIII) and HRu 3 (CO) 9 [CH 2 C(C 6 H 5 )C 2 ] (VII). The crystal structure of VII has been determined by X-ray diffraction methods. Crystals are triclinic, space group P 1 with Z = 2 in a unit cell of dimensions a 9.675(8), b 14.096(12), c 8.985(8) A, α 93.78(8), β 117.17(11), υ 92.15(8)°, V 1085(2) A 3 . The structure has been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least-squares to R = 0.057 for 3715 observed reflections. The molecule is formed by a triruthenium cluster, in a nearly equilateral arrangement, bound to nine terminal CO groups; one hydridic hydrogen atom is bridge-bonding two ruthenium atoms on one side of the cluster. The substituted acetylene is bound to the three metals via a σ bond to one ruthenium and two η bonds to the other two ruthenium atoms, in a way quite similar to that found in the analogous t=butyl acetylide complex (I). The olefinic CC bond distance is regular (1.337 A) indicating that there is no conugative interaction of the olefin with the cluster.

Alkyne trimerization on carbonyl ruthenium clusters. Synthesis and crystal structure of Ru3(CO)8(HC2But)3

Abstract The title complex is a minor product of the reaction of Ru3(CO)12 or of HRu3(CO)9(C2But) with excess of 3,3-dimethyl-but-1-yne (t-butyl-acetylene); better yields of the product are obtained by reacting η-C5H5)2Ni2(HC2But) with Ru3(CO)12, probably because of the known ability of nickel in promoting alkyne trimerization. The crystal structure has been determined by X-ray methods. Crystals are triclinic, space group P1 with Z = 2 in a unit cell of dimensions a = 11.665(8) b = 15.292(12), c = 8.877(7) A, α = 109.45(8) β = 100.68(8), γ = 94.57(7)°. The structure has been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least-squares to R = 0.046 for 2999 observed reflections. The complex consists of a bent arrangement of three Ru atoms forming RuRu bonds nearly perpendicular to each other. Eight (six terminal and two bridging) carbonyls coordinate to them and a ligand, deriving from trimerization of the alkyne, forms two σ-bonds with the central Ru atom, giving origin to a metalla-cyclopentadiene ring. The terminal Ru atoms lie on the opposite sides with respect to this ring and are η-bonded to four carbon atoms of it.

Preparation, spectroscopic and magnetic characterization of a new series of two-dimensional transition metal compounds. The x-ray structure of poly-bis(thiocyanato-N)-bis-μ- [1,2,4] triazolo [1,5-a] pyrimidine-N1,N3)iron(II)

The synthesis of a series of polynuclear compounds of general formula [M(tp) 2 (NCS) 2 ] n (M = Mn, Fe, Co, Ni and tp = [1,2,4]triazolo[1,5− a ]pyrimidine, C 5 H 4 N 4 ) is described. The compounds are X-ray and IR isostructural and were further characterized by ligand field and magnetic susceptibility measurements. The structure of the iron compound was determined by X-ray diffraction methods. It crystallizes in the orthorhombic space group Aba 2, with a =8.028(2), b =20.422(6), c =10.129(5) A. The structure has been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrtx least-squares to R = 0.040 for 706 observed reflections. The structure consists of octahedral iron complexes in which the metal atom is coordinated by two nitrogen atoms from two monodentate NCS groups and by four nitrogen atoms from four symmetry-related tp molecules; each organic ligand bridges two metal atoms through both non-bridgehead triazole nitrogen atoms, joining the octahedral complexes in a layered system where the Fe···Fe distance is 6.49 A.

On some copper(I) perthiocarboxylates and their reactions with tertiary phosphines. Crystal structure of tetra(p-tolyldithiocarboxylato)tetracopper(I), [CuS2C-p-tolyl]4, and of [bis(triphenylphosphine)(p-tolyldithiocarboxylato)copper(I)] triphenylphosphine sulfide, [CuS2C-p-tolyl(PPh3)2]•PPh3S

Abstract Some copper(I)perthiocarboxylates [CuS 3 CAr] 4 ( I ) ( Ia , ArPh; I b, Ar p -tolyl) were prepared in high yields from the corresponding aldehydes and ammonium polysulfide in basic medium. By reacting them with triphenylphosphine in different ratios, formation of PPh 3 S occurred and the following series of products could be isolated: [(CuS 3 CAr) 2 (CuS 2 - CAr) 2 ]py 2 ( II ); [CuS 2 CAr] 4 ( III ); [(CuS 2 CAr) 4 - (PPh 3 ) 2 ] ( IV ); [CuS 2 CAr(PPh 3 ) 2 ] ( V ). In the case of p -tolyl the complex [CuS 2 CAr(PPh 3 ) 2 ]·PPh 3 S ( VIb ) was also obtained. Some significant IR and NMR ( 13 C, 31 P) data of the above compounds are reported. The crystal structures of compounds IIIb and VIb were established by single crystal X-ray diffraction methods. Crystals of IIIb are triclinic, space group P 1 , with a =13.879(4), b =10.324(3), c =13.479(4) A,α=99.04(2), β=113.31(3), γ= 92.34(2)° and Z =2. Crystals of VIb are also triclinic, space group P 1 , with a =15.833(5), b = 10.999(3), c =15.690(5) A, α=103.12(3), β= 90.88(2), γ=94.05(2)° and Z =2. The structures have been solved by direct and Fourier ( IIIb ) and by Patterson and Fourier ( VIb ) methods and refined by blocked full-matrix least-squares to R =0.059 for IIIb and R =0.051 for VIb . The structure of IIIb consists of discrete units of four copper atoms bound to sulfur atoms from four p -tolyldithiocarboxylate groups acting as tridentate ligands. A sulfur atom of each ligand coordinates to one only copper atom and the other bridges two adjacent metals so that each metal is pseudo-trigonally surrounded by three sulfur atoms. In the structure of VIb monomeric complexes are present in which the metal atom is pseudo-tetrahedrally coordinated by two phosphorous atoms from triphenylphosphine ligands and by two sulfur atoms from one chelating p -tolyldithiocarboxylate group. Triphenylphosphine sulfide molecules are also present in the crystals of VIb . The complex autoxidative reactions of some dithiocarboxylates in pyridine, which cause a partial transformation of the sulfur atoms in coordinated ‘SO 4 ’ groups, were also investigated.

Synthesis and spectroscopic characterization of a new class of heterotetranuclear compounds with thiocyanate groups as bridging ligands. The X-ray structure of bis-(μ-tetrakis(thiocyanato-S)mercury(II)-N,N′)diaquahexakis(5.7-dimethyl[1,2,4] triazolo[1,5-a] pyrimidine-N3) dicobalt(II)

Abstract The synthesis and characterization of a novel type of heterotetranuclear compounds of general formula [MHg(dmtp) 3 (SCN) 4 (H 2 O)] 2 [M = Mn, Co, Ni(II) and dmtp = 5,7-dimethyl[1,2,4] triazolo[1,5-a] pyrimidine] are described. Infrared spectra show the presence of both S-coordinating and N,S-bridging thiocyanate ligands. Ligand-field spectra indicate an ocahedral coordination geometry for the transition-metal ions. The structure of one of the three, mutually isomorphous, compounds was determined by X-ray diffraction methods. Crystals of [CoHg(dmtp) 3 (SCN) 4 (H 2 O)] 2 are triclinic, space groups P 1 with a = 11.481(9), b = 13.975(11), c = 11.479(8) A, α = 101.08(6), β = 90.11(7), γ = 77.24(6)°, Z = 1. The structure was solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least-squares to R = 0.038 for 2392 independent observed reflections. The structure consists of centrosymmetric heterotetranuclear complexes formed by thiocyanate groups bridging heterometals. Mercury is tetrahedrally coordinated by sulphur atoms from thiocyanate groups (HgS bonds ranging from 2.457 to 2.601 A), two of which bridge two centrosymmetric Co atoms. Three N atoms from dmtp ligands and one oxygen from a water molecule complete the octahedral coordination of Co (CoN bonds: 2.11, 2.14 and 2.18 A; CoO w bond: 2.08 A). Intramolecular hydrogen bonds between water hydrogens and N atom sfrom a dmtp molecule and a non-bridging thiocyanate group respectively stabilize the tetranuclear species. Magnetic suspectibility studies indicate that the magnetic exchange between the metal ions is very weak.

Transition metals complexed to ordered mesophases. Synthesis and crystal structure of (8-hydroxyquinolinato)[2-[4′-methoxyphenylazo-N2)-5-methoxyphenyl]palladium(II)

Abstract The synthesis and characterization of the complex [Pd(quin)(azbz)] are described (quin = 8-hydroxyquinolinate and azbz = 2-(4′-methoxyphenylazo)-5-methoxyphenyl ligands, the latter being a derivative of p,p′-dimethoxyazobenzene, which exhibits liquid crystalline behaviour). The structure of the complex was determined by X-ray methods. Crystals are triclinic, space group P 1 , with a = 10.225(5), b = 11.092(4), c = 9.365(3) A; α = 105.65(2), β = 94.08(3), γ = 105.69(3)° and Z = 2. The structure was solved from diffractomer data by Patterson and Fourier methods and refined by full-matrix least-squares to R = 0.033 for 3395 independent observed reflections. The palladium atom is in a square planar arrangement involving nitrogen and carbon atoms from the azbz ligand [Pd-N(2) = 2.012(4) and Pd-C(10) = 1.939(5) A] and oxygen and nitrogen atoms from the quin ligand [Pd-O(1) = 2.118(4) and Pd-N(1) = 2.118(4) A]. In the crystals the PdII complexes are associated in pairs in columnar stacks (the stacking separation in each diadic units is of 3.304 A with a metal-metal distance of 3.424 A). These stacking interactions could be responsible for the different thermal behaviour of the complex (not exhibiting mesomorphic properties) with respect to the liquid crystalline p,p′-dimetoxyazobenzene.

Multi-site bound hydrocarbyls on osmium clusters. The reactions of t-butylacetylene with Os3(CO)12 and H2Os3(CO)10. Characterization of the products and crystal structure of HOs3(CO)10(HCCHBut)

Abstract As part of a study of the role of hydridoacetylide and hydridoalkenylosmium clusters as intermediates in the synthesis of heterometallic osmium-nickel derivatives, 3,3-dimethylbut-1-yne complexes of Os 3 (CO) 12 and H 2 Os 3 (CO) 10 were synthesized and characterized. The structure of the hydridovinyl compound HOs 3 (CO) 10 (μ-η 2 -CHCHBu t ) has been determined by X-ray diffraction; the crystals are monoclinic, space group P 2 1 / n with a 13.861(10), b 17.177(11), c 9.267(7) A, β 108.01(4)° and Z = 4. The structure has been solved from diffractometer data by direct and Fourier methods and refined by full-matrix least-squares to a R value of 0.052 for 2290 observed reflections. This cluster is one of the few μ-η 2 -alkenyl compounds to have been structurally characterized. The alkenyl-ligand bridges the Os(2)Os(3) edge forming a σ-bond to Os(2) and a π-bond to Os(3). The C(11)C(12) bond length of the alkenyl ligand is 1.38(4) A. The orientation of the ligand in the cluster and the NMR behaviour of the cluster are discussed. Relationships between the various clusters derived from t-butylacetylene are outlined.