Showing papers in "Journal of Chemical Crystallography in 1984"

Aggregation and solvation of a lithium aryloxide

Abstract: {Li[OC6H3-2,6-(tBu)2]THF}2, synthesized from phenol and LiH, is shown by X-ray crystallography to exist in the solid as a centrosymmetric dimer with two bridging phenoxides. Terminal THF ligands (envelope conformation) complete trigonal planar coordination about Li. The THF ligand plane lies in the Li2(μ-O)2 plane, while the phenyl ligands are perpendicular to this same Li2O2 plane. This explains the unusual1H NMR chemical shifts of the THF ligand. THF binds to Li as a dipole rather than using one of the two ether lone pairs. Crystallographic data (−160°C):a=18.799(3) A,b=18.758(6),c=15.697(5), andZ=4 in space groupPbca (no. 61). The final quality indices areR(F)=6.2% andR w (F)=5.9% for 1535 unique data.

The refined structure of ribonuclease-A at 1.45 Å resolution

Abstract: Features of the refined X-ray crystal structure of bovine pancreatic ribonuclease-A at 1.45 A resolution are described. The positions of the protein atoms have been determined within the range 0.004–0.05 A, and of solvent atoms, assumed to be oxygens, within the range 0.08–0.13 A. The present model contains 127 solvent molecules, taken to be water, and a sulfate anion located in the active site. Mean square atomic displacement parameters,U iso, refined for each atom, give an indication of the mobility of different parts of the structure. Main-chainU iso values tend to be less than side-chain values, having an average value of 0.15 A2 compared to 0.25 A2. Both main-chain and side-chain averageU iso values tend to increase with distance from the center of gravity of the molecule. Side-chain averageU iso values also tend to increase with the number of atoms in the side-chain, with different distributions for ring and chain type residues. Side-chain conformations have been analyzed and found on the whole to follow commonly observed distributions. A notable exception to this is the active-site residue His-119 which occupies two distinct sites. Apart from two small clusters of eight and seven atoms respectively, the solvent molecules are distributed in quite small numbers on the protein surface. The solvent clusters occur in the active-site region and, together with the sulfate anion, appear to stabilize residues in this region. Sixty-three solvent atoms have only one identified hydrogen bond contact. Of the rest, 36 form two, 22 form three, and 6 form four hydrogen bonds. There is a marked tendency for the mean square displacement parameter,U iso, for the solvent atoms to be lower for atoms with many hydrogen bond contacts than for those with fewer contacts.

Stacking interactions in the acridine dyes: spectrophotometric data and crystal structure of acridine orange hydroiodide and acridine orange hydrochloride monohydrate

Abstract: The crystal structure of acridine orange hydroiodide and that of acridine orange hydrochloride monohydrate have been solved by X-ray diffraction analysis. The absorption spectra of both derivatives in the solid state have also been reported and compared with those of the acridinium ion in solution. The stacking interactions of the acridine orange molecule in both derivatives is discussed in the light of the visible absorption spectra in the solid state and in solution.

X-ray and Raman studies of single crystals of CsSbF6

Abstract: Crystals of CsSbF6 belong to the rhombohedral space groupR¯3-C 3i 2 witha=7.904(1)andc=8.261(1) A,V=446.95 A3,Z=3,Dc=4.11 gcm−3. The antimony atom is surrounded by six fluorine atoms in a nearly perfect octahedral configuration with Sb-F 1.875(9) A, while 12 fluorine atoms surround the cesium atom with closest contact 3.116 A. Polarized Raman spectra of single crystals of CsSbF6 have been obtained, and it is shown that these results can be interpreted in terms of a unimolecular rhombohedral structure. The small distortion from an octahedral arrangement for the SbF 6 − group is clearly reflected in the spectra. The Raman results are in better agreement with the space groupR¯3m-D 3d 5 than withR¯3-C 3i 2 , but this conclusion must be regarded with caution since the two features in the vibrational spectra of CsSbF6 which can be used to distinguish between the two structures are weak and ill-defined.

The crystal structure of LiBr·(CH3OCH2CH2OCH3)2

Abstract: The crystal structure of LiBr·(CH3OCH2CH2OCH3)2 has been determined from counter data and refined by full-matrix least-squares techniques. The crystals belong to the monoclinic space groupC2/c (C 2 6 , No. 15) witha=13.518(4),b=8.007(3),c=12.252(4) A,β=98.08(2)°, andD calc=1.35 gcm−3 forZ=4. The finalR value for 489 observed reflections is 0.033. The lithium and bromine atoms lie on a crystallographic two-fold axis. The structure consists of discrete LiBr·(CH3OCH2CH2OCH3)2 units. The Li-Br separation is 2.57(1) A. The two DME molecules are coordinated to the lithium atom through the four oxygen atoms at an average Li⋯O separation of 2.09(3) A.

Crystal structure of 1,5-dibromonaphthalene and of disordered 1,8-dibromonaphthalene

Abstract: The crystal structure of 1,5-dibromonaphthalene, C10H6Br2, has been determined from a single crystal x-ray study. The compound crystallizes in the monoclinic space groupC2/c with four molecules per unit cella=14.576(5),b=4.049(1),c=15.046(6) A, andβ=92.18(3)°. The structure was solved by the execution of the programDirdif in space groupP1. Full-matrix least-squares refinement (inC2/c) using 544 reflections with sinθ/λ 6σ(∥F0∥) converged withR=0.039 andRw=0.050. The results of an X-ray study of 1,8-dibromonaphthalene (P21/c, a=8.050(4),b=10.898(5),c=11.083(5) A,β=107.83(4)°; disordered;R=0.11) are included as an appendix.

An infrared, Raman, and single-crystal x-ray study of cesium hexafluorophosphate

Abstract: CsPF6:M,=277.87, cubic,Fm3m-O h 5, witha 8.228(5) A,V 557(1) A3,Z=4,D x =3.31 Mg m−3, λX(MoKα)=0.7107 A,μ(MoKα)=6.85 mm−1 F(000)=496,R=0.0327 for 114 reflections. The PF6 ion exhibits orientational disorder; infrared and Raman spectra show that its point symmetry is lower thanm3m-O h , in agreement with the equilibrium atomic positions found in the X-ray study. The rule of mutual exclusion is not obeyed in the spectra of CsPF6; this can be explained if the disorder also involves a small shift of the P atom away fromm3m-O h site symmetry. Such an effect could not be modelled in the X-ray study. The deviation from octahedral symmetry of PF6 is small and, from a consideration of the vibrational spectra of the MPF6 series, it is concluded that both the reorientational and other motions such as librational and torsional oscillations contribute toward the breadth of some vibrational modes.

Crystal and molecular structure of [(C6H5)3Sb]3CuCl·CHC13

Abstract: The X-ray crystallographic structure determination of [(C6H5)3Sb]3 Cu(I)Cl·CHC13 reveals that the compound crystallizes in the triclinic space groupP¯1 witha=18.827(3),b=14.279(3),c=14.399(3) A,α=84.43,β=87.39(2), andγ=75.18(1)°,V=2734.7(9) A3,Z=2. Least-squares refinement based on 4689 independent observed data [(F obs)2≥3σ(F obs)2], resulted in a finalR value of 0.064. The cocrystallized solvent molecules were highly disordered. The coordination about Cu(I) of three Sb(C6H5)3 molecules and one Cl ligand is approximately tetrahedral. The Cu-Cl distance, 2.235(5) A, is extremely short in comparison to previously reported Cu-Cl distances in four-coordinate Cu(I) complexes. In keeping with the short Cu-Cl distance are very long Cu-Sb distances, av. 2.554(5) A.

Molecular structure of an ancient folk medicine: Berberine hydrogen sulfate

Abstract: The crystal structure of the versatile folk medicine berberine hydrogen sulfate, (C20H18NO4)+HSO 4 − , has been determined by the heavy-atom method and refined by blocked full-matrix least-squares refinement. The crystals are triclinic, space groupF¯1,a=20.370(5),b=7.435(2),c=27.427(6) A,α=97.700(9),β=116.222(9),γ=85.456.(8)°,Z=8,D x =1.556 g cm−3,D m =1.549(5) g cm−3. The structure refined toR=0.070 for 1659 observed reflections withI(hkl)≧2.5σ[I(hkl)]. The ring system of the berberine molecule is approximately planar, with both −OCH3 groups twisted slightly out of the plane. Heterocyclic ringB has a half-chair conformation with a pseudo-two-fold axis bisecting the bonds C(9)-C(10) and C(7)-C(8), diagonal to the isoquinoline groupAB. The five-membered ringE has an envelope conformation, the apical atom C(1) being out of plane.

Crystal and molecular structure of an amber polymorph of 4-methyl-2-nitroacetanilide (MNA)

Abstract: The crystal and molecular structure of a third polymorph of 4-methyl-2-nitroacetanilide has been determined by X-ray diffraction It crystallizes in the monoclinic system, space groupP21/c,Z=4,a=10158(2),b=11635(2),c=8041(2) A andβ=9455(2)° Using 1027 unique reflections, the structure was solved by the method of vector verification and refined by full-matrix least squares, which gave convergence toR=0080 The structure consists of nearly planar molecules, all approximately parallel to one another with their longitudinal axes parallel tob The amide group forms an intramolecular hydrogen bond with the nitro group Molecules related byc-glide are stacked alongc in a very distinct columnar form The columns are held together by dipole-dipole interactions between close antiparallel carbonyl groups or between close antiparallel nitro groups

Structure of tetra( n -butyl)ammonium tetraiodo-μ,-μ′-diiododiplatinate(II), [( n -C 4 H 9 ) 4 N] 2 [Pt 2 I 6 ]

Abstract: The crystal structure of [(n-C4H9)4N]2[Pt2I6] has been determined from X-ray data measured by counter methods. It crystallizes in the monoclinic space groupP21/c (C 2 -5 , No. 14) with unit cell constantsa=14.457(4),b=14.036(4),c=23.696(5) A,β=101.02(3)°, andD c =2.30 g cm−3 forZ=4. Full-matrix least-squares refinement led to a finalR value of 0.049 for 1786 independent observed reflections. The [Pt2I6]2− anion is planar to within 0.07 A and exhibits an average Pt-I bridging bond length of 2.559(4) A and average Pt-I terminal distance of 2.571(7) A. Of the two independent [(n-C4H9)4N]+ cations, one approaches a ¯42m-D 2d conformation, the other an approximate ¯4-S4 conformation.

Synthesis and structure of (η5-C5H5)2Hf(η1-NC4H4)2

Abstract: The crystal structure of (η5-C5H5)2Hf(η1-NC4H4)2 has been determined from X-ray data measured by counter methods. The title compound is isostructural with (η5-C5H5)2Zr(η1-NC4H4)2, and crystallizes in the monoclinic space groupP21/c (C 2 5 , No. 14) with unit cell constantsa=9.605(3),b=8.174(3),c=19.487(4) A, β=90.85(3)°, andZ=4 forD c=1.91 gcm−3. Full-matrix least-squares refinement gave a finalR value of 0.068 for 2154 independent observed reflections. The two cyclopentadienyl rings are η5-coordinated to the hafnium atom at an average Hf-C(η5−) distance of 2.51(1) A. The Hf-N-centroid (σ-pyrrolyl) angles average 166°.

Crystal and molecular structure of diaquobis(1,1′-dimethyl-2,2′-diimidazolylsulfide)copper(II) methylsulfate, (C8H10N4S)2Cu(II)(OH2)2(CH3OS03)2

Abstract: The crystal and molecular structure of the title complex has been determined. The space group isP21/n, witha=8.460(3),b=8.503(3),c=20.341 (8) A,β=98.41(3) andZ=2. The ligand molecules chelate the CuII such that the metal has a tetragonally distorted octahedral geometry; four N atoms occupy the equatorial plane and two H2O molecules occupy the axial positions. The average Cu-N and Cu-O distances are 2.005(6) and 2.47(1) A, respectively. The novel ligand, 1,1′-dimethyl-2,2′-diimidazolylsulfide was formedin situ from a methanolic solution of copper(II) sulfate pentahydrate and 1-methylimidazole-2-thiol. The measured spectral parameters (visible, EPR, and photoelectron spectroscopy) correlate well with the molecular structure.

Steroids and related studies. Part 60. Crystal and molecular structures of 17β-(2-hydroxyethyl)-3β-and 3α-pyrrolidino-17a-aza-D-homo-5-androstenes: HS-625 form 1, (3β-pyrrolidino) and HS-625 form 2 (mixed-3α and -3β-pyrrolidino epimers)

Abstract: The crystal structures of two forms of 17β-(2-hydroxyethyl)-3-pyrrolidino-17a-aza-D-homo-5-androstene (HS-625) are reported. In HS-625 (aqueous solvate) form 1, moleculeA, and HS-625 (anhydride) form 2, moleculeB, the pyrrolidine group is 3-β substituted, while in HS-625 (anhydride) form 2, moleculeC has its pyrrolidine ring α-substituted. HS-625 form 1 is orthorhombic, space groupP212121, witha=7.089(4),b=11.502(6),c=28.975(16) A,Z=4; form 2 is triclinic, space groupP1, witha=14.013(8),b=12.572(6),c=6.688(4) A, α=95.187(20), β=103.491(21); γ=86.210(20)°,Z=2. MoleculesA andB have similar geometry, differences in moleculeC being related to strain caused by the unusual 3-α ring substituent which also produces a pronounced kink in the backbone of the molecule. An unusual feature of the analysis of form 1 is the location of the water hydrogens in the difference electron density well above background. None of the OH hydrogens was located. Both structures are hydrogen bonded, but the pyrrolidine nitrogen N(31) in moleculeC is heavily congested and is unable to act as an acceptor. The hydroxyethyl side chain, important for activity, has a different conformation in the three molecules (t,g, t,-g, andt,t respectively).

Crystal and molecular structure of bis(tetramethyl-ammonium)bis(maleonitriledithiolato)cuprate(II). Structure of C16H24CuN6S4

Abstract: The crystal and molecular structure of the title compound, C16H24CuN6S4, is reported. The crystals are monoclinic: space groupP21/c,Z=4,a=13.230(3),b=11.518(9),c=16.269(6) A,β=95.07(2)°. The structure was solved by the heavy-atom method, and refined by full-matrix least squares toR=0.059 for 1907 unique diffractometer data. The anions have approximately 222 (D2) symmetry, with an angle of 41.14(1)° between the normals to planes of the ligands. The amino atoms of the cations have an approximate tetrahedral configuration. The anions are well separated from each other, the closest Cu-Cu distance being 7.811 (2) A. The anionic units can be considered as being stacked alongb in columns. The metal atoms are not collinear along the stack axis, but form a kind of kinked chain.

Infrared spectroscopic study of water in the hydrates of calcium nitroprusside: Ca[Fe(CN)5NO]·nH2O (n=1,4)

Abstract: The infrared absorption bands due to the water molecules in calcium nitroprusside monohydrate and tetrahydrate were studied using partial deuteration and low-temperature techniques. An assignment of these bands based on the possible hydrogen bonds existing in the crystal lattice is proposed. Additional infrared spectroscopic data on the monohydrate and the anhydrous compound are included.

Synthesis, properties, and molecular structure of bis(thiobenzoato-S)tellurium(II), C14H10O2S2Te(II)

Abstract: The synthesis, properties, and structural characterization of the title compound, C14H10O2S2Te, are reported. The crystals are monoclinic, space groupC2/c (No. 15) witha=24.369(6),b=4.333(2),c=14.569(3) A, andβ=109.56(2)°,V=1449.57 A3,M=402, andD x =1.843 g cm−3 forZ=4. The structure was solved by the heavy-atom method and refined by full-matrix least squares toR=0.029 andR w =0.027 for 772 diffractometer data. Crystal structure analysis and IR spectroscopic study indicate that the tellurium is covalently bonded to sulfur. There are weak secondary interactions between tellurium and oxygen which complete an S2O2 coordination around tellurium.

Crystal structure of the Ni(ClO4)2 complex of the mixed donor macrocycle, 9-ane N2O: resolution of disorder by force-field calculation

Abstract: The crystal structure of the nickel perchlorate complex of the macrocyclic ligand 9-ane N2O [Ni(ClO4)2·C12H28N4O2] has been determined by X-ray diffraction. The observed space group,Cm (No. 28), occurs because of disorder across the mirror plane. The disorder was resolved by force-field calculation and superposition of the calculated structures in a molecular trial-and-error procedure. The coordination geometry is octahedral and the centrosymmetric cation contains a pseudo-three-fold axis.

The crystal structure of [NBu 4 n ][AlI4]

Abstract: The crystal structure of [NBu 4 n ]f AlI4] has been determined from counter data, and refined by full-matrix least-squares techniques. The crystals belong to the monoclinic space groupP21/n (an alternate setting ofP21/c-C 2h 5 , No. 14) witha=11.661(3),b=20.828(5),c=11.674(3) A,β=98.39(2)°, andDcalc=1.84 g cm−3 forZ=4. The finalR value for 1587 observed reflections is 0.051. The structure consists of discreet [NBu 4 n ]+and [AlI4]− ions. The [AlI4]− anion is approximately tetrahedral and exhibits an average Al-I bond length of 2.52(1) A. The closest cation-anion, I⋯C, contact is ¯4 A. The compound was isolated from the reaction of I2 with [NBu 4 n ][Al2Me6I].

An application ofDirdif to troublesome heavy-atom structures

Abstract: When a heavy-atom structure determination presents difficulties, the structure may be solved by expanding the data to triclinic symmetry, putting one heavy atom at the origin, and using the programDirdif (direct methods applied todifference structure factors) to locate the remaining heavy atoms.

The crystal and molecular structure of [K·DB-18-C-6][AlMe3NO3]·0.5C6H6

Abstract: The use of dibenzo-18-crown-6 in the synthesis of trimethylaluminum adducts of KNO3 results in the formation of a 1/1 adduct, [K·DB-18-C-6]-[AIMe3NO3]. The crystal structure of [K·DB-18-C-6][AlMe3NO3]-has been determined from single-crystal X-ray diffraction data collected by counter methods. The title compound crystallizes in the monoclinic space groupP21/c (No. 14) with unit cell parametersa=11.804(3),b=28.828(4),c=9.118(3) A, β=96.61(3)°, andD calc=1.23 forZ=4. Least-squares refinement gave a final conventionalR value of 0.045 for 983 independent observed reflactions. The potassium atom is centered among the six oxygen atoms of the crown at an average K⋯O contact of 2.74(2) A. Its environment is completed by an oxygen atom of a nitrate anion (2.88 A) and a benzo group (>3.44 A) of a neighboring crown ether. The trimethylaluminum moeity is coordinated to the nitrate anion by an oxygen atom at an Al-O bond distance of 1.92(1) A.

Crystal structure of 3,3-(p-N,N-dimethylaminophenyl)-6-N,N-dimethylaminophthalide, (crystal-violet lactone)

Abstract: The title compound is C26H29N302,M r ,=415.54, monoclinic,P21/n,a=12.228(1),b=17.385(2),c=11.786(1) A,V c =2308.7 A3,Z=4,D x =1.19 Mg m−3,μ=5.29 cm−1,F(000)=888. FinalR=0.046 for 2301 independent reflections. Three cyrstallographically distinct nitrogens were found, with the molecule possessing the expected propeller shape.

N , N ′-(1,2-phenylene)bis(pyridoxal-hydrochlorideiminato)copper(II): crystallographic and spectroscopic studies

Abstract: (C22H22CuN4O4Cl2 2·7H2O is triclinic,C i− 1 t-P1. Unit cell dimensions at 293 K area=12.028(3),b=20.378(6),c=11.387(3) A, α=113.10(2),β=84.13(2), γ=95.99(2)°,V=2547.5 0A3,D c =1.573 Mg. m−3, andZ=2. The structure has been determined from single-crystal data collected with a four-circle diffractometer and refined from 3904 reflections down toR=0.054 andR w =0.058. The asymmetric unit is built from two independent A and B molecules in which the copper atom has a square pyramidal environment in A and an octahedral one inB. Intermolecular Cu-O (hydroxymethyl groups) contacts observed in the solid state are partially present in aqueous solutions.

Crystal and molecular structure of tetra-n- butylammoniumbis(stilbenedithiolato)- nickelate(III)

Abstract: The crystal and molecular structure of the title compound, C44H56NS4Ni, are reported. Crystals are triclinic, space groupP¯1 (No. 2) withZ=2 in a unit cell of dimensionsa=8.874(2) A,b=9.549(5) A,c=26.025(7) A,α=97.22(3)°,β=95.06(2)°, andγ=98.75(3)°. The structure was solved by Patterson and Fourier methods and refined by full-matrix least squares toR=0.062 for 2910 unique diffractometer data. The metal atom of the anion has an approximate square-planar configuration and the nitrogen atom of the cation an approximate tetrahedral configuration. The anions as well as the cations are well separated, the closest Ni⋯Ni and N⋯N approaches being the lattice repeat of 8.874(2) A.

Crystal and molecular structure of 3-(2-(1,10-phenanthrolyl)-5,6-diphenyl-1,2,4-triazine-chloroaquotriphenyltin(IV) (1:1)

Abstract: 3-(2-(1,10-Phenanthrolyl))-5,6-diphenyl-1,2,4-triazine-chloroaquotriphenyl-tin(IV) (1:1) crystallizes in the orthorhombic system:a=19.195,b=9.144,c=21.642 A,Z=4, space groupPca21 (No. 29). The structure was determined using the procedure for difference structures (Dirdir) with CuKα diffractometer data, and refined by block-diagonal least squares toR=0.031 for 3287 observed reflections. The tin atom is 5-coordinate with the three phenyl groups forming the equatorial plane. A chlorine atom and a water molecule complete the coordination. The triazine moiety does not coordinate directly to the metal atom. The only interaction is due to two N ⋯ H-O hydrogen bonds formed between two nitrogen atoms from the ligand and the water molecule.

Molecular structure of thiocyanatotris (2,2'-iminodiethanoldithiocarbamato) tellurium(IV) monohydrate

Abstract: The synthesis, properties, and structural characterization of the title compound, C16H30N4O4S7Te(IV)·H2O, are reported. The crystals are monoclinic, space groupP21/n, withZ=4 in a unit cell of dimensionsa=13.291(5),b=21.306(6),c=10.450(1) A, 0=104.25(2)° and,Vc=2868 A3. The structure was solved by the heavy atom method and refined by full-matrix least squares toR=0.025 andRw=0.027 for 2894 reflections. The dithiocarbamate groups are linked in an unequal bidentate manner with Te-S average distance 2.695(1) A. The thiocyanate group is bonded through the sulfur atom with much larger Te-S length [2.964(2) A].

The role of X-ray crystallography in drug design: Identification of the two isomers 17β-hydroxy-17α-methyl-5(β andα)-androstano-(2,3-C)-1′, 2′, 5′-oxadiazole (HS804 and HS805) (steroids and related studies, Part 62)

Abstract: Crystal structure analysis has distinguished between the two epimers 17β-hydroxy-17α-methyl-5(β andα)-androstano-(2, 3-C)-1′, 2′, 5′-oxadiazole (HS804 and HS805) HS804 is trigonal,P32,a=14820(4),c=7177(3) A,Z=3 and HS805 is orthorhombic,P212121,a=9507(4),b=18528,c=10048(4) A,Z=4 The crystal structures were solved by direct methods and refined by full-matrix least squares toR=00376 for 1419 reflections (HS804) andR=for 1819 reflections (HS805), using diffractometer measured data with CuKα radiation The two molecules have different ring connections,A/Bcis in HS804 andA/B trans in HS805, the planar oxadiazole ring beingcis fused to ringA in both molecules RingA is strained in both molecules

Isolation and crystal structures of triethylenediamine-hydroquinone (1/1) and triethylenediamine-phenol (1/2)

Abstract: Two crystalline adducts of triethylenediamine with hydroquinone [N(CH2CH2)3N·C6H4(OH)2,I] and phenol [N(CH2CH2)3N·2C6H5OH,II] have been isolated and characterized by X-ray analysis. ComplexI crystallizes in the monoclinic space groupC2/c, witha=11.944(2),b=9.491(2),c=11.986(2) A,β=121.70(1)°, andZ=4. Both molecular components occupy sites of symmetry 2, and are linked alternately by N ⋯ H-O hydrogen bonds to form infinite zigzag chains. Crystals ofII are also monoclinic, with space groupP21/c,a=12.987(2),b=6.376(1),c=21.350(3) A,β=106.94(1)°, andZ=4. The structure is composed of discrete hydrogen-bonded molecular aggregates corresponding to the stoichiometric formula. The triethylenediamine moieties in both adducts closely approximate to the idealizedD 3 h conformation. The structures have been refined toR values of 0.097 (I) and 0.092 (II) using, respectively, 479 and 1580 observed MoKα data.

Studies on rare earth carboxylates. III: X-ray and IR studies on Ln(C6H4OHCOO)3•H2O (Ln=La−Ho or Y)

Abstract: The rare earth salicylate monohydrates Ln(C6H4OHCOO)3·H2O (Ln=La-Ho or Y) were prepared and subjected to X-ray powder diffractometric and infrared absorption spectroscopic investigations. The salts from lanthanum to gadolinium are found to be isomorphous and are indexed on a monoclinic unit cell with space groupP21/c-C 2h 5 (No. 14). Certain dissimilarities between the powder patterns of isomorphous terbium and dysprosium compounds and those of the lighter rare earths necessitated independent indexing of these two compounds, which are found to be monoclinic with space groupP21/c-C 2h 5 . Holmium and yttrium salts are isomorphous and are monoclinic with space groupP2/m-C 2h 1 (No. 10). The assignments of some of the observed bands to certain characteristic vibrations of various functional groups in the spectra of these salts have been done.