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The reactivity of the cyclic primary aliphatic amines cyclopropyl-, cyclopentyl- and cyclohexylamine with cis- and trans-[PtCl 2 (NCMe) 2 ], under the same experimental conditions, is compared. Whereas cis-[PtCl 2 (NCMe) 2 ] yields the neutral diamidine compounds, the reactions with trans-[PtCl 2 (NCMe) 2 ] take place either with addition or substitution processes yielding the neutral diamidine complexes trans-[PtCl 2 (Amidine) 2 ], the monocationic trans-[PtCl(Amine)(Amidine) 2 ]Cl and the dicationic trans-[Pt(Amine) 2 (Amidine) 2 ]Cl 2 salts. An NMR and ESI study indicate that the main species formed is the monocationic trans-[PtCl(Amine)(Amidine) 2 ]Cl complex. The X-ray structure of trans{PtCl 2 {N(H)=C(CH 3 )NHCHCH 2 CH 2 } 2 ] is reported and its supramolecular arrangement is described.

The reaction of cis - and trans -[PtCl 2 (NCCH 2 Ph) 2 ] with a 5-fold excess of MeNH 2 and Me 2 NH in CH 2 Cl 2 at −10 °C affords in high yield the bis-amidine derivatives cis - and trans -[PtCl 2 { Z -N(H) C(NHMe)CH 2 Ph} 2 ] ( 1a , 2a ) and cis - and trans -[PtCl 2 { E -N(H) C(NMe 2 )CH 2 Ph} 2 ] ( 3a , 4a ), respectively. The complexes were characterized by means of elemental analysis, multinuclear NMR and FT-IR techniques. The X-ray diffraction analysis was carried out for trans -[PtCl 2 { Z -N(H) C(NHMe)CH 2 Ph} 2 ] ( 2a ). Moreover, the in vitro cytotoxicity for the new derivatives was evaluated in a wide panel of human tumor cell lines.

New silver(I) complexes have been synthesised from the reaction of AgNO3, monodentate PR3 (PR3 = P(o-tolyl)3, P(m-tolyl)3, P(p-tolyl)3, P(p-C6H4F), SeP(C6H5)3) or bidentate tertiary (dppe = bis(diphenylphosphane)ethane, dppf = 1,1′-bis(diphenylphosphane)ferrocene) phosphanes and potassium dihydrobis(3-nitro-1,2,4-triazolyl)borate, K[H2B(tzNO2)2]. These compounds have been characterized by elemental analyses, FT-IR, ESI-MS and multinuclear (1H and 31P) NMR spectral data. The adduct {[H2B(tzNO2)2]Ag[P(m-tolyl)3]2} has been characterized by single crystal X-ray studies. In the former, the H2B(tzNO2)2 acts as a monodentate ligand utilizing the coordinating capability of only one of the additional (exo-) ring nitrogens to complete the coordination array about the silver atom.

An improved synthesis of platinum acetate is reported in detail. This tetrameric complex reacts with PPh3 or P � /n-Bu3 at room temperature to give the thermodynamically unstable bis-substituted trans -[Pt(OAc)2L2] complexes, which are not easily accessible via other routes. The structure of the new compound trans -[Pt(OAc)2(PPh3)2] has been determined by X-ray analysis. # 2003 Elsevier B.V. All rights reserved.

Lanthanide(III) complexes with composition Ln(nic)(H 2 O) n (pic) 3 (nic) (Ln=Pr, Nd n =8; Tm n =7) (pic=picrate, nic=nicotinamideN-O) were obtained by reaction of the hydrated lanthanide picrate with nicotinamideN-oxide in ethanol. They were characterized by elemental analysis and IR spectra. The molecular structures of Pr, Nd and Tm complexes were established by X-ray crystallography. Different triclinic phases have been detected for the isostructural Nd and Pr derivatives. They are nine coordinated to eight water molecules and a monodentate nic ligand while the apparently isomorphous Tm derivative looses a water molecule with a eight coordination number and a coordination geometry changing from tricapped trigonal prism (Pr, Nd) to square antiprismatic.

The reactions of cis-[PtCl2(NCMe)2] with a fivefold excess of the primary aliphatic amines RNH2 (R=Me, Et, Pri, But) in CH2Cl2 at −10 °C afford in high yield the bis-amidine complexes cis-[PtCl2{ZN(H)C(NHR)Me}2], where both amidine ligands assume the Z configuration. The corresponding reactions of trans-[PtCl2(NCMe)2] with RNH2 (R=Me, Et, But) give a mixture of the bis-amidine trans-[PtCl2{ZN(H)C(NHR)Me}2] and the mono-amidine trans-[PtCl2(NCMe){ZN(H)C(NHR)Me}] derivatives, which could be isolated as pure products operating with a platinum nitrile complex:amine molar ratio of 1:50 or 1:1, respectively. The reaction of trans-[PtCl2(NCMe)2] with a 50-M excess of PriNH2 affords the bis-amidine bis-amine dicationic complex trans-[Pt(H2NPri)2{ZN(H)C(NHPri)Me}2]Cl2, which has been characterized also by X-ray diffraction analysis. The reactions of cis- and trans-[PtCl2(NCMe)2] with the secondary aliphatic amines R′R″NH yield the bis-amidine complexes cis- and trans-[PtCl2{EN(H)C(NR′R″)Me}2] (R′, R″=Et) and/or cis- and trans-[PtCl(NCMe){EN(H)C(NR′R″)Me}2] (R′, R″=Et; R′=Me, R″=But), where the amidine ligands have the E configuration. The compound trans-[PtCl2(NCMe){EN(H)C(NMeBut)Me}] has been characterized by single crystal X-ray diffraction. All the complexes have been characterized by IR, 1H and 13C NMR spectroscopies. The Z or E configuration of the amidine ligand can be readily deduced by 1H NMR data.

The compounds [quinolinium]4[Bi2Cl10] (1), [isoquinolinium]4[Bi2Cl10].2H2O (2) and [8-hydroxyquinolinium]4[BiCl6]·Cl·2H2O (3) have been obtained by reacting bismuthate oxide and the appropriate base in HCl acid medium. The crystal structures of 1 and 2 consist of quinolinium and isoquinolinium cations, respectively, interacting through hydrogen bonding with [Bi2Cl10]4− dimers. The different degree of interactions in the two derivatives causes significant differences in the bond distances of the anions. The crystal structure of 3 is made of [BiCl6]3− and Cl− anions and 8-hydroxyquinolinium cations. Hydrogen bond interactions including the N-bonded and O-bonded H atoms together with an interstitial chlorine atom stabilize the entire crystal structure.

The complexes trans-[FeH(NCR)(dppe)2][BF4] (1) (R=NH2, NMe2, NEt2 or NC(NH2)2; dppe=Ph2PCH2CH2PPh2) and trans-[FeL(NCR)(depe)2]Yn (R=NH2, NMe2, NEt2 or NC(NH2)2; depe=Et2PCH2CH2PEt2; Y=BF4 or BPh4; (2), L=Br, n=1; (3), L=NCR, n=2) have been prepared by treatment of trans-[FeHCl(dppe)2] (in THF and in the presence of Tl[BF4]) or trans-[FeBr2(depe)2] (in MeOH and in the presence of [NBu4][BF4] or Na[BPh4]), respectively, with the appropriate cyanamide. NMR and Mossbauer spectral, as well as FAB mass spectrometric data are reported. Mossbauer partial isomer shift (PIS) and partial quadrupole splitting (PQS) parameters have been estimated for the cyanamide and dppe ligands and rationalised, with the overall IS and QS, in terms of π- and σ-electronic effects, the cyanamides behaving as more effective σ-donors and weaker π-acceptors than organonitriles. FAB MS fragmentation patterns are also proposed. The crystal structures of 1 (R=NH2) and 3 (R=NEt2, Y=BF4) are reported.

The cyanoguanidine complex cis-[Pt(NCNC(NH2)2)2(PPh3)2][BPh4]2, prepared by reacting cis-[PtCl2(PPh3)2] with cyanoguanidine in the presence of Na[BPh4], readily reacts with methanol to give cis-[(PPh3)2PtNHC(OMe) = NC(NH2) = NH)] [BPh4] containing a novel type of azametallcycle whose molecuar structure is established by X-ray crystallography. Its formation involves metal-promoted nucleophilic addition of the alcohol to the cyano group of a cyanoguanidine ligand, combined with deprotonation of the guanidine unit which then chelates the Pt(II) centre.

The syntheses of the ligand bis(benzylamide)diethylenetriaminepentaacetic acid (BBA-DTPA) and its Gd(III) and Lu(III) complexes are reported. The solid state structure of Lu(III) BBA-DTPA was determined in a single crystal X-ray diffraction study. The lutetium ion adopts a mine-coordinate geometry, which is best described as a distorted tricapped prism. Eight coordination sites are occupied by the ligand (three nitrogen atoms, two carboxamide oxygens and three carboxylate oxygens) and the ninth site is occupied by the oxygen atom of a water molecule. The VT 13 C NMR spectra of Lu(III) BBA-DTPA are consistent with the presence of three isomers in solution. Water proton relaxation rates have shown that Gd(III) BBA-DTPA displays an analogous behaviour to that observed for other Gd(III) complexes of related bisamide derivatives of DTPA. The solubility of Gd(III) BBA-DTPA has been markedly improved by the presence of an excess of hydroxypropyl-β-cyclodextrin. The thermodynamic stability of the inclusion complex has been evaluated by measuring the proton relaxation enhancement upon addition of β-cyclodextrin.

The TDCO thiocyanate complexes Eu(NCS)3 TDCO and Yb(NCS)3TDCO (TDCO = 1,7,10,16-tetraoxa-4,13-diazacyclooctadecane) have been synthesised and their X-ray structure determined. Both are monoclinic with 4 neutral molecules in the unit cell of dimensions a = 16.438(4), b = 15.211(3), c = 9.334(2) A , β = 90.37(3)°, V = 2333.8(9) A 3 , space group P2t/n for Eu and a = 17.481(3), b = 8.020(2), c = 18.056(3) A , β = 118.12(3)°, V = 2232.6(9) A 3 , space group P2t/c for Yb. They consist of nine-coordinated metal centres linked to six donor atoms of the macrocyclic ligand and to three monodentate isothiocyanate ligands situated on opposite sides of the macrocycle. The two structures present different conformations of the TDCO ligand. The mean bond lengths are EuO 2.56(2), YbO 2.498(9), EuN(ring) 2.60(1); YN(nng) 2.518(8) and EuN(CS) 2.44(1), YbN(CS) 2.365(9) A consistent with the difference in the Eu and Yb ionic radii.

The chloro complexes trans-[Pt(Me)(Cl)(PPh3)2], after treatment with AgBF4, react with 1-alkynes HCCR in the presence of NEt3 to afford the corresponding acetylide derivatives trans-[Pt(Me) (CCR) (PPh3)2] (R = p-tolyl (1), Ph (2), C(CH3)3 (3)). These complexes, with the exception of the t-butylacetylide complex, react with the chloroalcohols HO(CH2)nCl (n = 2, 3) in the presence of 1 equiv. of HBF4 to afford the alkyl(chloroalkoxy)carbene complexes trans-[Pt(Me) {C[O(CH2)nCl](CH2R) } (PPh3)2][BF4] (R = p-tolyl, n = 2 (4), n = 3 (5); RPh, n = 2 (6)). A similar reaction of the bis(acetylide) complex trans-[Pt(CCPh)2(PMe2Ph)2] with 2 equiv. HBF4 and 3-chloro-1-propanol affords trans-[Pt(CCPh) {C(OCH2CH2CH2Cl)(CH2Ph) } (PMe2Ph)2][BF4] (7). T alkyl(chloroalkoxy)-carbene complex trans-[Pt(Me) {C(OCH2CH2Cl)(CH2Ph) } (PPh3)2][BF4] (8) is formed by reaction of trans-[Pt(Me)(Cl)(PPh3)2], after treatment with AgBF4 in HOCH2CH2Cl, with phenylacetylene in the presence of 1 equiv. of n-BuLi. The reaction of the dimer [Pt(Cl)(μ-Cl)(PMe2Ph)]2 with p-tolylacetylene and 3-chloro-1-propanol yields cis-[PtCl2{C(OCH2CH2CH2Cl)(CH2C6H4-p-Me}(PMe2Ph)] (9). The X-ray molecular structure of (8) has been determined. It crystallizes in the orthorhombic system, space group Pna21, with a = 11.785(2), b = 29.418(4), c = 15.409(3) A, V = 4889(1) A3 and Z = 4. The carbene ligand is perpendicular to the Pt(II) coordination plane; the PtC(carbene) bond distance is 2.01(1) A and the short C(carbene)-O bond distance of 1.30(1) A suggests extensive electronic delocalization within the PtC(carbene)O moietry.

The title complex was prepared by reacting Pd(AcO) 2 first with dppp and then with TsOH·H 2 O in MeOH at r.t. It is highly active in COC 2 H 4 copolymerization in MeOH. It has been characterized by IR and 1 H and 31 P NMR spectroscopies. The X-ray structure consists of a packing of monomeric palladium cations and tosylate anions in the ratio 1:1. The palladium atom is in rather distorted square coordination.

The 1,3-oxazine complexes cis- and trans-[PtCl2{ N C(R)OCH2CH2C}H22] (cis: RCH3 (1a), CH2CH3 (2a), (CH3)3C (3a), C6H5 (4a); trans:R CH3 (1b), C6H5 (4b)) were obtained in 51-71% yield by reaction in THF at 0 °C of the corresponding nitrile complexes cis- and trans-[PtCl2(NCR)2] with 2 equiv. of −OCH2CH2CH2Cl, generated by deprotonation of 3-chloro-1-propanol with n-BuLi. The cationic nitrile complexes trans-[Pt(CF3)(NCR)(PPh3)2]BF4 (RCH3, C6H5) react with 1 equiv, of − OCH2CH2CH2Cl to give a mixture of products, including the corresponding oxazine derivatives trans-[Pt(CF3){ NC(R)OCH2CH2C CH2}(PPh3)2]BF4 (5 and 6), the chloro complex trans- [Pt(CF3)Cl(PPh3)2] and free oxazine NC(R)OCH 2 CH 2 C H2. For short reaction times (c. 5–15 min) the oxazine complexes 5 and 6 could be isolated in modest yield (37–49%) from the reaction mixtures and they could be separated from the corresponding chloro complex (yield 40%) by taking advantage of the higher solubility of the latter derivative in benzene. For longer reaction times (> 2 h), trans-[Pt(CF3)Cl(PPh3)2] was the only isolated product. Complex 6 was crystallographically characterized and it was found to contain also crystals of trans- [PtCl{ NC(R)OCH 2 CH 2 C H2}(PPh3)2]BF4, which prevented a more detailed analysis of the bond lengths and angles within the metal coordination sphere. The 1,3-oxazine ring, which shows an overall planar arrangement, is characterized by high thermal values of the carbon atoms of the methylene groups indicative of disordering in this part of the molecule in agreement with fast dynamic ring processes suggested on the basis of 1H NMR spectra. It crystallizes in the trigonal space group P 3 , with a=22.590(4), b=15.970(3) A, γ=120°, V=7058(1) A3 and Z=6. The structure was refined to R=0.059 for 3903 unique observed (I⩾3σ(I)) reflections. A mechanism is proposed for the conversion of nitrile ligands to oxazines in Pt(II) complexes.

The interaction of the new, potentially binucleating, ligand 2,6-diacetylpyridine-bis(1′-phthalazinylhydrazone) (H 2 dapz), containing only nitrogen donor atoms, towards nickel(II), copper(II) and zinc(II) salts is reported. Depending on the nature of the counteranions, Ni II and Cu II ions selectively enter in one of the two ‘compartments’ present in the ligand. Analytical and spectroscopic characterizations of five series of mononuclear complexes [dapzM], [H 2 dapzMCl 2 ], [HdapzMCl], [(H 2 dapz) 2 M][ClO 4 ] 2 , [HdapzM][ClO 4 ], coming from reactions of metal acetates, metal chlorides and metal perchlorates, respectively, and the ligand in the bisdeprotonated, monodeprotonated and undeprotonated forms, are reported together with some interconversion reactions. Some tentative stereochemical assignments of these compounds are reported on the basis of their physicochemical properties. Different behaviour has been observed in the case of zinc(II) chloride and perchlorate. Crystal structure analysis on the bisdeprotonated complex [dapzNi] 2 , shows that the compound is dimeric, with the metal ions octahedrally coordinated into the upper compartment, and the pyridine nitrogens bridging the two nickel atoms.

Complexes with formula [LnL8](ClO4)3 (LnLaHo) and [LnL7](ClO4)3 (LnErLu, Y; Lδ-valerolactam) were synthesized and characterized by conductance measurements, IR spectra, X-ray powder diffraction patterns, electronic absorption spectra of the neodymium and emission spectrum of the europium compounds. X-ray single crystal structural analysis of the neodymium compound showed that it forms monoclinic crystals, space group P21/n with a=25.491(4), b=16.074(3), c=13.051(3) A and β=90.15(3)°. Neodymium ions are coordinated in a square-antiprismatic arrangement to eight oxygen atoms of the δ-valerolactam ligands. The average NdO bond length is 2.45(1) A. The non-coordinated ClO4− ions are partially disordered.

The diaminocarbene complexes cis-Cl2(PPh3)Pt[ CN(Bu t )CH 2 CH 2 N H] (1) and cis-Cl2Pt[ CN(C 6 H 4 -p-OMe)CH 2 CH 2 N H]2 (2) have been prepared by reaction of the corresponding isocyanide derivatives with aziridine/ClCH2CH2NH3+Cl− and aziridine alone, respectively. The aminooxycarbene complex cis-Cl2Pt[ CN(C 6 H 4 -p-OMe)CH 2 CH 2 O ]2 (3) has been prepared by reaction of the bis-isocyanide derivative with 2-chloroethanol/n-BuLi. The dimeric complexes {(PPh3)BrPd[μ- CN(Me)CH 2 CH 2 N C,N]}2 (4), {(PPh3)ClPd[μ- CN (C6H4-p-OMe)CH2CH2NC,N]}2 (5), {(PPh3)ClPt[μ- CN(C 6 H 4 -p-OMe)CH 2 CH 2 N C,N]}2 (6) have been prepared by deprotonation reaction of the NH group of the corresponding mononuclear derivatives with n-BuLi. The X-ray structure of {(PPh3)ClPt[μ- COCH 2 CH 2 N C,N]}2 (7) is reported. The structural model was refined to R=0.055 (Rw=0.061) for 7442 independent reflections. Crystal data: triclinic, space group P , a=19.564(3), b=16.497(3), c=13.243(2) A, α=88.93(3), β=97.88(3), γ=91.97(3)° Z=4. The crystal contains two crystallographically independent dimer units and a disordered dichloroethane molecule. Each dimer is formed by two bridging carbene ligands which are coordinated to one platinum on one side via a PtN bond and to the second platinum via a PtC bond. The coordination geometry around each platinum atom is an irregular square with deviations in the tetrahedral direction of the bonded atoms. The anodic behaviour of these and related monocarbene, dicarbene or dinuclear dicarbene complexes has been studied by cyclic voltammetry and controlled potential electrolysis in aprotic media and shown to present irreversible oxidation waves commonly with a multi-electron character (up to four electrons) and involving liberation of protons (in a number similar to that of the transfered electrons) conceivably resulting from anodically induced NH or CH bond cleavage, the former at an amino group and the latter occurring at methylene groups activated by adjacent amino- or oxy-carbene moieties.

In solution, the complex trans -[PdCl(C 5 H 4 N C 2 )(PMe 2 Ph) 2 ] ( 1 ) is in equilibrium with a small amount of the binuclear species [{PdCl(μ-C 5 H 4 N C 2 , N )(PMe 2 Ph)} 2 ] ( 2 ), which can be isolated upon recrystallization. The compound 1 is easily N-protonated by HClO 4 to the 2-pyridylium product trans -[PdCl(C 5 H 5 N C 2 )(PMe 2 Ph) 2 ]ClO 4 ( 3 ), which crystallizes in the orthorhombic space group P2 1 2 1 2 1 , with cell parameters a =15.761(3), b =14.369(2), c =11.132(2) A and Z =4. The X-ray crystal structure analysis of 3 , using 3744 observed reflections in the refinement and resulting in a final R value of 0.0298, shows that the coordination around palladium is essentially square-planar with PdC=1.970(5), PdCl=2.368(2), PdP(1)=2.317(1) and PdP(2)=2.318(1) A. The planar pyridine ring is perpendicular to the coordination plane, and the NH group is involved in hydrogen bonding with an oxygen of the perchlorate anion, at a contact distance of 2.08(6) A. Extensive hydrogen bonding occurs also in dichloromethane solution and accounts for the hindered rotation of the 2-pyridylium ligand around the PdC 2 bond.

Thorium tetrachloride forms a 1:3 complex, ThCl 4 ·3L, with N,N -diethyl N ′, N ′-dimethylurea (dedmu); and 1:2 complexes with dedmu, N,N -diisopropyl N ′, N ′-dimethyl (dibdmu), N,N -diisobutyl- N ′, N ′-dimethyl (dibdmu), N,N -diisopropyl N ′, N ′-diphenyl (dipdpu), N,N,N ′, N ′-tetramethyl (tmu) and N,N,N ′, N ′-tetraethylurea (teu) have been obtained. A dichloromethane solvate, ThCl 4 ·3L·CH 2 Cl 2 , where L= N,N ′-dimethyl- N ′, N -diphenylurea (dmdpu), has also been obtained. The crystal and molecular structure of ThCl 4 (dmdpu) 3 ·n-pentane has been determined from three dimensional X-ray diffraction data. The cell is triclinic, space group P 1 , with a =16.826(3), b =16.019(3), c =12.131(2) A, α=11O.4(1), β=106.6(1) and γ=59.4(1)° and Z =2. Full matrix least-squares refinement with 7963 intensity observations reached convergency with R =0.053 and R w =0.058. The coordination polyhedron about the seven-coordinate thorium atom is a pentagonal bipyramid with two chlorine atoms in apical positions. The average bonding distances are ThO=2.392(5), ThCl eq =2.743(3) and ThCl ax =2.696(3) A. The IR spectra of the complexes are also reported.

By reacting neodymium nitrate hexahydrate with the cryptand 〈222〉 in methanol, the complex Nd2-(NO3)6[C18H36O6N2]·H2O was obtained and analyzed by single-crystal X-ray diffraction. The cell is triclinic P 1 with a = 14.870(2) A, b = 13.261(2) A, c = 8.832(1) A, α = 91.2(1)°, β = 93.4(1)°, γ = 87.6(1)°, Z = 2 and U = 1736.6 A3. The structure was refined by least-squares methods to the conventional R = 0.039 for 6177 observed reflections. The compound contains the cations [Nd〈222〉(NO3)]2+ and the anions [Nd(NO3)5·H2O]2−, and is isostructural with the samarium analogue. Solid state fluorescence spectra of the title complex were measured at room and liquid nitrogen temperature, and the transitions 4F3/2 → 4I9/2 and 4F3/2 → 4I11/2 analyzed.

Systematic studies to arrive at some first examples of the sterically congested complex type Cp3Ln(NCR)2 (Cp = η5-C5H5, Ln = lanthanoid element) resulted in the preparation and detailed spectroscopic characterization of analytically pure representatives of this type with Ln = La, Ce and Pr, but not with Nd (R = CH3, and C2H5 for Ln = La only). The crystal and molecular structures of representatives of the isomorphous series Cp3Ln(NCCH3)2, (Ln = La, Ce, Pr) were determined from three-dimensional X-ray diffraction data. The compounds crystallize in the orthorhombic space group Pnca (standard group Pbcn) with: a = 14.940(3), b = 14.074(3), c = 8.596(2)A, Z = 4, R = 0.070, Rw = 0.079 for 1633 intensity data (La derivative, I); a = 14.906(3), b = 13.974(3), c = 8.502(2)A, R = 0.041, Rw = 0.047 for 1378 intensity data (Ce derivative, VII); a = 14.936(3), b = 13.986(3), c = 8.498(2)A, R = 0.031 for 1372 intensity data (Pr derivative, IX). According to the X-ray crystallographic results, the novel complexes are trigonal bipyramidally coordinated with three η5-bonded Cp rings in the equatorial plane (Ln—ring centre distances 2.62, 2.64 for La, 2.58, 2.59Afor Ce and 2.57, 2.57Afor Pr and two acetonitrile groups in the axial positions (Ln N 2.785 for La, 2.749 for Ce, 2.752 for Pr). The range of the distances in the three derivatives is in agreement with the trend in the crystal radii along the lanthanoid series. Pure 1:2 adducts involving any alkyl group larger than R = C2H5 could not be isolated. The relative stabilities of the novel Cp3Ln(NCR)2 systems, with respect to the decreasing ionic radius (i.e. from La to Nd) and to the variable space demanded by the group R, are in excellent accord with independent expectations based on the recently developed cone packing model (‘SAS-rule’) for f-element organometallics.

The synthesis, thermal behaviour and crystal structure of fumarate dioxouranium(VI) dihydrate are described. The compound crystallizes in the monoclinic system, space group P 2 1 /n with a = 9.952(3), b = 7.502(2), c = 5.571(2) A, β = 98.6(3)° and Z = 2.555 observed reflections (I > 3σ( I )) were refined to a final R = 0.0235. The fumarate ligands bridge the uranyl groups in chains. The geometry around the uranium is approximately hexagonalbipyramidal, with the two water molecules coordinated to the uranyl group.

The structure of the title compound has been determined from single-crystal X-ray analysis. The triclinic cell has dimensions a = 13.225(3), b = 10.246(2), c = 8.283(2) A, α = 112.1(1), β = 101.9(1) and γ = 85.0(1)°, space group P 1 , Z = 2. The structure was refined by least square methods to the conventional R value 0.032 for 2791 observed reflections. The molecule is formed by [GdCl2EtOH(18-crown-6)]+ cations and Cl− anions. In the cation the crown ether ligand, which includes the Gd ion, is folded away from the side where a chlorine and the ethanolic oxygen are coordinated to the metal ion; a second chloride ion is coordinated on the opposite side.

Le complexe du titre cristallise dans le systeme monoclinique, groupe P2 1 /n et sa structure est affinee jusqu'a R=0,096. La molecule presente une libration elevee, particulierement au niveau des coordinats Cp. Nature electrostatique de la liaison entre l'ion metallique et les coordinats Cp

The crystal and molecular structures of ThCl 4 (depa) 3 (1) (depa = N,N-diethylpropionamide) and Th(NCS) 4 (dmpa) 4 (2) (dmpa = N,N-dimethylpropionamide) have been determined from three-dimensional X-ray diffraction data. The compounds crystallize in space group P2 1 /n (1) and P2 1 /a (2), with a = 18.107(5), b = 10.347(3), c = 17.867(5) A , β = 108.5(1)°, Z = 4 (1) and a = 22.759(6), b = 13.763(4), c = 11.910(3) A , β = 91.4(1)° and Z = 4 (2). Full matrix least-squares refinement of both structures gave for (1) with 3126 intensity data R = 0.046 and Rw 0.046 and for (2) with 3480 intensity data R = 0.050, Rw 0.054. The different steric constraints imposed by the ligand give rise to different coordination numbers. In (1) the coordination polyhedron about the seven co-ordinate thorium atom is a pentagonal bipyramid with two chlorine atoms in the axial positions, an unusual geometry for Th(IV) species. The average bonding distances are ThO = 2.340(9), ThCl eq = 2.754(3) and ThCl ax = 2.692(3) A . In (2) the less hindering dmpa ligand favours the presence of four of them in the metal coordination sphere in a distorted square antiprismatic coordination geometry. ThO and ThN average 2.37(1) and 2.49(2) A respectively.

Amide complexes of thorium tetrachloride often adopt a different stoichiometry to those formed by the same ligand with uranium tetrachloride, a difference which can be ascribed to the smaller radius of the U(IV) centre as compared with that of Th(IV). For example, with the amide depa (=EtCONEt2) the complexes 2UCl4·5depa [1] and ThCl4·3depa [2] are obtained. The former has been shown [1] to be ionic, [UCl3(depa)4]+[UCl5(depa)]−, with the 7-coordinate uranium atom in the cation adopting the rather unusual bipyramidal geometry which had already been observed [3] in the neutral complex U(NCS)4(dmiba)3 (dmiba = Me2CHCONMe2. It was therefore of interest to determine the structure of ThCl4·3depa in order to ascertain whether the coordination geometry was gain pentagonal bipyramidal, and also to investigate the structure of the probably 8-coordinate complex Th(NCS)4·4dmpa (dmpa = EtCONMe2) the preparation of which has also been reported recently [2]. Crystal Data ThCl4·3depa (1) (ThC21H45Cl4N2O3) M = 761.5, monoclinic P2 1 n , a = 18.107(4), b = 10.347(2), c = 17.867(4) A, β = 108.5(1)°, Z = 4,λ(MoKlga)0.71069 A. 3126 reflections with I⩾ 2.5σ (I) use in the structure solution and refinement, R = 0.046, Rw = Th(NCS)4·4dmpa (2) (ThC24H44N8O4S4) M = 821.0, monoclinic P2 1 a , a = 22.759(6), b = 13.763(4), c = 11.910(3) A. β = 91.4(1)°, Z = 4, λ(MoKα 0.71069 A. 3729 reflections with I ⩾ 2.5σ(1) used in the structure solution and refinement, R = 0.049, Rw = 0.053. The coordination geometry for (1) is pentagonal bipyramidal as shown in Fig. 1, with two chlorine atoms occupying the axial positions. This kind of geometry is common in seven-coordinate dioxouranium(VI) complexes, rather unusual for U(IV) compounds and the first example for that concentrating mononuclear Th(IV) derivatives. The ThCl axial bond distances (2.69 A av.) are shorter respect to the ThCl equatorials (2.75 A av.) as consequence of the different steric hindrance experienced by the anionic ligands. The coordination geometry for (2) (see Fig. 2) is nearly square antiprismatic. The substitution of the chlorine with the less hindering isothiocyanate ligand allows a higher coordination number around the thorium ion, while the changed of the neutral ligand does not seem of some effect. The ThN and ThO bond distances have the averaged values of 2.50 A and 2.38 A respectively.

The complexes M(NCS)4·xL (x = 2, M = U, L = Me3CCON(Pri)2(dippva); x = 3, M = Th, L = Me2CHCON(Pri)2(dipiba) and dippva, M = U, L = EtCON(Pr1)2(dippa), dipiba and dippva; x = 4, M = Th, L = MeCON(Pri)2(dipa), dippa and dipiba, M = U, L = dipa, dippa) and the solvates M(NCS)4·4dipa·CH2Cl2 (M = Th, U) have been prepared. Their i.r. and u.v.-visible (M = U only) spectra are reported. The crystal and molecular structure of U(NCS)4(dipa)4· CH2Cl2 has been determined by the heavy-atom method from X-ray diffractometer data and refined by least squares to R 0.029 for 1135 independent reflections. The crystal is tetragonal, space group P 4 21c, with Z = 2, a = 15.663(4) and c = 10.512(3) A. The coordination geometry about the 8-coordinate uranium atom is dodecahedral with the N atoms of the NCS groups occupying the dodecahedral A sites and the ‘dipa’ O atoms the B sites. The bonding distances of UO and UN are 2.363(8), and 2.444(11) A respectively.