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Reactions of lanthanide chlorides or trifluoracetates (tfa) or picrates with trimethylphosphate alone in the first two cases or trimethylphosphate plus 1,10-phenanthroline or 2,2′;6′,2′′-terpyridine in the third, result in the formation of crystalline products containing dimethylphosphate (dmp–). Single crystal X-ray structural characterisation of these materials has shown that the stoichiometrically simple Ln(dmp)3 species obtained with chloride reactants and the lighter lanthanides are polymeric and commonly dimorphic, while the stoichiometrically more variable mixed dmp/tfa complexes have structures closely related to one phase of the Ln(dmp)3 family, and the presence of picrate and aza-aromatic ligands enables the isolation of Y and Lu derivatives containing binuclear species. In all, the dmp– ligands adopt exclusively the κ1 O ;κ1 O′ bridging mode, the overall results indicating that this should apply to the complete lanthanide series. Structural studies of the products of reaction of different lanthanide(III) salts with trimethylphosphate show them to contain dimethylphosphate as a bridging bidentate rather than a chelate ligand across the lanthanide series. [ABSTRACT FROM AUTHOR]

Reactions of the lanthanide(iii) picrates (picrate = 2,4,6-trinitrophenoxide = pic) with 1,10-phenanthroline (phen) and 2,2′:6′,2′′-terpyridine (terpy) in a 1 : 2 molar ratio have provided crystals suitable for X-ray structure determinations in instances predominantly involving the lighter lanthanides. In all, the aza-aromatic ligands chelate the lanthanide ion, none being found as 'free' ligands within the lattice. The complexes of 1,10-phenanthroline have been characterised in two forms, one unsolvated (Ln = La, Sm, Eu; monoclinic, C 2/ c , Z 8), one an acetonitrile monosolvate (Ln = Gd; monoclinic, P 21/ a , Z 4), the latter being the only previously known form (with Ln = La). In both forms, the LnIII is nine-coordinate, in an approximately tricapped trigonal-prismatic environment, with two picrate ligands chelating through phenoxide and 2-nitro group oxygen atoms, the third being bound through phenoxide-O only. The 2,2′:6′,2′′-terpyridine complexes, all acetonitrile monosolvates defined for Ln = La, Gd, Er, and Y (monoclinic, C 2/ c , Z 4), are ionic, one picrate having been displaced from the primary coordination sphere. For Ln = La, the two bound picrates are again chelating, making the LaIII 10-coordinate in a distorted bicapped square-antiprismatic environment but in the other species they are bound through phenoxide-O only, making the LnIII ions eight-coordinate in a distorted square-antiprismatic environment. Stacked arrays of the ligands can be found in both series of complexes, with intramolecular picrate–picrate and picrate–aza-aromatic stacks being prominent features. Structure determinations on complexes of lanthanide(III) picrates with aza-aromatic ligands provide examples of various stacking arrays. The chain of [La(terpy)2(pic)2]+ cations (shown in space-filling mode) present in the lattice of [La(terpy)2(pic)2](pic)·CH3CN involves both intra- and intermolecular heterogeneous stacks. [ABSTRACT FROM AUTHOR]

The carboxamide-O donor ligands dimethylacetamide (dma) and N -methylpyrrolidinone (nmp) form complexes of lanthanide picrates, Ln(pic)3, of stoichiometry Ln(pic)3(carboxamide)3 in a remarkable variety of phases. Complexes [Ln(pic)3(dma)3], Ln = La, Ce, Nd, Sm, Gd, Yb, Lu, and Y, adopt the 9-coordinate molecular form of tricapped trigonal-prismatic coordination geometry seen to predominate, as two stereoisomers, in related species involving dimethylsulfoxide (dmso), trimethylphosphate (tmp), and hexamethylphosphoramide (hmpa) but as four different phases (depending on Ln), none of which is the same as for the previously known La complex. For Ln = Pr, 9-coordinate species of composition [Pr(pic)3(dma)2(alcohol)] (alcohol = ethanol and propan-2-ol) have been characterised and a low quality determination indicates that a similar species (with propan-2-ol) is formed by Y. For nmp, the composition [Ln(pic)3(nmp)3] is maintained across the series for Ln = La, Ce, Pr, Nd, Gd, Er, Tm, Yb, and Lu but 9-coordination is not for Ln = Er, Tm, Yb, and Lu. A decreased coordination there is a result of one or two picrate ligands acting as phenoxide-O donors only, a marked contrast with the analogous Ln(pic)3 complexes with dmso, tmp, hmpa, and dma, where picrate chelation is universal, but with some parallel to related ScIII complexes. Several polymorph pairs can be identified among the nmp complexes. Structural studies of the adducts of lanthanide picrates with dimethylacetamide (dma) and N-methylpyrrolidinone (nmp) add further variety to the nature of simple O-donor ligand complexes of these picrates. Polymorphism is readily detected in the dma complexes, while, with the heavier lanthanides, nmp causes partial detachment of the picrate ligands. [ABSTRACT FROM AUTHOR]

Adducts of the form Ln(pic)3(tmp)3 (Ln = lanthanide(iii); pic = picrate = 2,4,6-trinitrophenoxide; tmp = trimethylphosphate, (MeO)3PO) have been prepared for extremal Ln = La, Lu and some intermediate members, also Y, and characterised by single crystal X-ray structure determinations as unsolvated, mononuclear, molecular species. The lanthanide atom has nine-coordinate, tri-capped trigonal prismatic stereochemistry in all cases, the picrate components behaving as O , O ′-bidentate ligands chelating through the phenoxy- and an adjacent O -nitro oxygen atom, thus: [Ln(tmp- O)3(pic- O , O ′)3]. Two isomeric forms are found, one mer in which the three unidentate tmp- O ligands coordinate in cis -sites spanning the upper and lower triangles and a capping site of the coordination sphere, and fac , in which all three unidentate ligands occupy the mutually cis -sites of one triangular face. The mer isomer has been described as an isomorphous series in a monoclinic P 21/ c , Z 4, form, for Ln = La, Ce, Pr, Nd, Sm, Gd, Lu, and Y, presumptively accessible for the full gamut of Ln. The fac -isomer also crystallises in a monoclinic P 21/ c form, Z 8, two independent molecules of similar stereochemistry here comprising the asymmetric unit and described for Ln = Eu, Lu(isomorphous); it has also been described in a triclinic P CH19176_IE1.gif , Z 2 form for Ln = La. Trimethylphosphate (tmp) is the first of a series of related O-donor solvates of lanthanide(III) picrates to give isomeric mer- and fac- [Ln(pic)3(tmp)3] complexes. [ABSTRACT FROM AUTHOR]

Addition of various oxygen-donor ligands (L, all dipolar, aprotic solvents), to a solution of hydrated scandium picrate in weakly coordinating solvents (S), has yielded several crystalline adducts of the form Sc(pic)3(L) m (· n S) in which all ligands L are coordinated, subsequently characterised by a series of single crystal X-ray studies. For L = dmso, m = 3 and the picrate anions are all bound as phenoxide-O donor units, while for nmp, dma, tmp, and hmpa, m = 2 and one of the bound picrates becomes bidentate through phenoxide- and nitro-O donation. For L = ompa, m = 2 and two picrate ligands are bound through phenoxide-O while one is displaced from the primary coordination sphere. All complexes contain six-coordinate ScIII, confirming that this coordination number is a consequence of ligand bulk. Six-coordination of ScIII is observed throughout in crystalline adducts of scandium picrate with dmso, dma, nmp, tmp, hmpa, and ompa, although with variations in the adduct stoichiometry and the coordination mode of picrate. [ABSTRACT FROM AUTHOR]

Single crystal X-ray structure determinations have previously been described for picrate salts of a variety of nitrogen bases. Herein, these have been extended to encompass monoprotonated mono- and oligo-dentate cyclic nitrogen-donor ligand systems derived from pyridine, some via saturation (piperidine and morpholine) and others via lateral extension of the aromatic system (2,2'-bipyridine, 1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline, bis(2-pyridyl)amine, 2,2':6',2"-terpyridine, and 8-hydroxyquinoline). Hydrogen-bonding interactions are dominant determinants of the structures, complemented by or in competition with parallel stacking of anion and (aromatic) base planes. Furthermore, nitro⋯nitro, nitro⋯7i and phenoxy-0⋯7i inter-species contacts play a significant role in the crystal packing. It also appears that cation...anion interactions arising from CH(adjacent to NH)⋯O(o-nitro) interactions are more important than the available secondary bifurcating component associated with any NH⋯O(o-nitro) approach, resulting, in many cases, in a bidentate NH⋯HC base approach to an (ON)O⋯O⋯O(NO) triadic array. The nature of the anion-cation interactions and their importance are explored using the Hirshfeld surface method. The precision of the structure determinations establishes the quinonoid form of the picrate to be a widespread contributor. Theoretical calculations on picric acid and the parent pyridinium-picrate ion-pair confirm the energetic favourability of the base-triad approach and the dominance of the quinonoid resonance form. [ABSTRACT FROM AUTHOR]

Problems arising from the extensive disorder characteristic of the crystalline lattice of dmso solvates of metal perchlorates at room temperature can in many cases be ameliorated or removed at `low'' temperature. Present studies of several M(ClO4)n · 6dmso (n=2,3) species and Dy(ClO4)3 · 8dmso have allowed detailed definition of several homoleptic dmso-solvated metal cations, all of which contain dmso as an O-bound unidentate ligand and which appear to closely confirm the forms of solvated cations deduced from independent solution studies. [Copyright &y& Elsevier]

Novel [Rh(η-diene)Tpx] complexes of sterically encumbered Tpx ligands (Tpx = Tp4Bo, diene = cod, 1; nbd, 2; Tpx = Tp4Bo,5Me, diene = cod, 3; nbd, 4; Tpx = Tpa,3Me, diene = cod, 5; nbd, 6; Tpx = Tpa*,3Me, diene = cod, 7; nbd, 8) have been prepared by treatment of [Rh(η-diene)(μ-Cl)]2 with TlTpx (Tpx in general, in detail: Tp4Bo = hydrotris(indazol-1-yl)borate, Tp4Bo,5Me = hydrotris(5-methyl-indazol-1-yl)borate, Tpa,3Me = hydrotris(3-methyl-2H-benz[g]-4,5-dihydroindazol-2-y1)borate, Tpa*,3Me = hydrotris(3-methyl-2H-benz[g]indazol-2-yl)borate), and characterized by analytical and spectral data (IR, ¹H, 11B, and 13C NMR solution). The structures adopted by [Rh(nbd)Tp4Bo] 2, [Rh(cod)Tp4Bo,5Me] 3, [Rh(nbd)Tpa,3Me] 6, [Rh(nbd)Tpa*,3Me] 8, and [Rh(nbd)Tpa*,3Me*] 8* (incorporating a borotropomeric ligand), have been investigated. Low steric hindrance between the ligands in 2 and 3 permits κ³ coordination of the pyrazolylborate while the high steric encumbrance present in 6, 8, and 8* results in κ² ligands. The coordination modes of the ligands to the metal have also been established by 15N CPMAS studies of selected ligands and their corresponding Rh complexes. These spectroscopic data are in agreement with the 15N chemical shifts obtained by using quantum-chemical methods to assist reliable assignments of the experimental values, affording new insights into the extraction of structural information concerning the hapticity (κ² or κ³) of the poly(pyrazolyl)borate ligands to the Rh metal. [ABSTRACT FROM AUTHOR]