The crystal and molecular structures of di-μ-hydroxy-bis(di-2-pyridylamine)dinitratodicopper(II) and aqua-μ-formato-triformato-bis(di-2-pyridylamine)dicopper(II) monohydrate

The preparation, magnetic and spectroscopic properties, crystal and molecular structures of binuclear complexes of formulae [Cu₂(dpyam)₂(OH)₂(ONO₂)₂] (I), [Cu₂(dpyam)₂(O₂CH)₄(OH₂)].H₂O (II) are described. (I) consists of pairs of copper atoms linked by two hydroxo bridges. The co-ordination geometry at each copper atom is distorted square-pyramidal, the basal plane consisting of two hydroxo oxygen atoms and two nitrogen atoms from a dpyam ligand, while the axial co-ordination sites are occupied by nitrate oxygen atoms. The copper(II) ions in (II) are also in a distorted square-pyramidal environment. They are bridged by a formate group in an anti–syn configuration from a basal position to an axial position, while another axial position is occupied by the water oxygen atom. From magnetic susceptibility measurements at room temperature, both complexes are found to exhibit antiferromagnetic interactions and some magneto-structural trends are discussed.     

Metal cluster-induced desulphurization of N-(p-methoxybenzoyl)-S-benzoylsulphenamide. Crystal and molecular structures of [Os6(CO)20(μ4-S)(MeCN)]

Reaction of N-(p-methoxybenzoyl)-S-benzoylsulphenamide1 with [Os₃(CO)₁₀(MeCN)₂] at room temperature gives Os₃(CO)₁₀(μ₃-S)]2 and [Os₆(CO)₂₀(μ₄-S)(MeCN)]3 in moderate yield. The crystal structure of 3 has been determined. Complex 2 is an intermediate in the formation of 3. Complex 3 undergoes dissociation of CO to give [Os₆(CO)₁₉(μ₃-S)] and [Os₅(CO)₁₅(μ₄-S)].     

Bis-(tetraethylammonium)[tetraazidocuprate(II)] and catena-di-μ-1,1-azido-[di-μ-1,1-azido-bis-(2,4-dimethylpyridine)dicopper(II)]

Two new copper(II) azido complexes, namely bis-(tetraethylammonium)[tetraazidocuprate(II)] (1) and catena-di--1,1-azido-[di--1,1-azido-bis-(2,4-dimethylpyridine)dicopper(II)] (2), have been prepared and characterized by spectroscopic and crystallographic methods. Complex (1) consists of isolated NEt⁺ ₄ cations and [Cu(N₃)₄]^2– anions. The site symmetry around the copper atom in the anion is 4/m. Complex (2) features a 1 D chain structure, five coordinated square pyramidal copper(II) atoms with both azides functioning as -1,1-bridges. The i.r. spectra reveal that both complexes contain asymmetric azido ligands. The solid and solution electronic spectra of (1) and (2) show very strong absorption bands in the visible region associated with N^– ₃ Cu^II charge-transfer transitions. The e.p.r. spectra of powder samples and solutions at room temperature were recorded and discussed.     

The structure of di-μ-chloro- bis - {chloro( N,N -diethylethane-1,2-diamine-κ 2)copper(II)}

Dichloro(N,N-diethyl-ethane-1,2-diamine)copper(II) has copper(II) ions in square pyramidal coordination. The two nitrogen atoms of the diamine {Cu–N_primary?=?1.979(3), Cu–N_tertiary?=?2.108(2)?Å} and two chloride ions are in the basal plane {Cu–Cl1?=?2.2680(9), Cu–Cl2?=?2.2989(8)?Å}. A centrosymmetrical dimer di-μ-chloro-bis{chloro(N,N-diethylethane-1,2-diamine-κ²)copper(II)}, C₆H1₆Cl₂CuN₂, is formed by axial coordination by Cl2, trans to the tertiary nitrogen, to a second copper(II) ion, with Cu?···?Cuⁱ?=?3.4855(9) and Cl2–Cuⁱ?=?2.7860(8)?Å. The dimer is also linked by H-bond N1–H?···?Cl1ⁱ.     

Polyfluorothiolate derivatives of rhodium(I). Crystal and molecular structure of [Rh(μ-SC6HF4)(C8H12)]2

Summary The thiolato-bridged dinuclear compounds [Rh(-SR)-(COD)]₂, where R=p-C₆HF₄ (1),p-C₆H₄F (2) and CF₃ (3), are obtained from the chloro-bridged analogue by ligand exchange.Compound (1) crystallizes in the space group P₁ with a=9.740(3)Å, b=11.642(4)Å, c=13.997(6)Å, =103.87(3)°, =106.98(3)° and =105.10(2)°; z=2. In this dinuclear molecule both Rh atoms have a square planar coordination sharing one edge, namely the two sulphur bridging atoms. The Rh—Rh separation of 2.96 Å is consistent with at most a very weak metal-metal interaction. Upon addition of CO the dimeric [Rh(-SR)(CO)₂]₂ (4), (5) and (6) are obtained, but addition of PPh₃ affords the monomeric species [Rh(SR)(PPh₃)-(COD)] (7), (8) and (9). Reactions of the dimeric tetracarbonyl derivatives with PPh₃ vary with the nature of R; [Rh(-SR)(PPh₃)(CO)]₂ is obtained when R=p-C₆H₄F (10) and CF₃ (11) but monomeric [Rh(SR)-(PPh₃)(CO)₂] (12) is produced when R=p-C₆HF₄. The latter mononuclear compounds, with R=p-C₆H₄F (13) and CF₃ (14), are also formed by reaction of [Rh(SR)-(PPh₃)(COD)] with CO.     

Dimeric and polymeric copper(I) complexes. Synthesis and characterization of copper(I) complexes of di-2-pyridyl ketone oxime (DPKox) and crystal structures of [Cu(DPKox)Cl]2·2H2O and [Cu(DPKox)(NCS)]n

Copper(I) complexes with di-2-pyridylketone oxime (DPKox) of the type CuLX·nH₂O, n=1 for X=Cl and Br, and n=0 for X=I and SCN, have been synthesized and characterized. The overall physical results suggest tridentate and bidentate DPKox ligand in the Cl, Br and I, SCN complexes, respectively, and terminal X in the former but bridging X in the later. These complexes display MLCT bands in the visible region, but they do not fluoresce at room temperature. The structure determination has shown the chloride complex (1) to have a centro-symmetrically related dimeric unit, in which each copper atom is coordinated by Cl(1), N(1), N(2) and N(3) (of the second ligand molecule) in a distorted tetrahedral environment. Hydrogen bonds are formed by the O(1) of the oxime group and a lattice water molecule, and between different lattice water molecules and Cl(1). The structure of the thiocyanate complex (2) features tetrahedral geometry around copper atoms, a chelating bidentate DPKox ligand coordinating via one of the two pyridyl nitrogens, N(1), and N(oxime) only and μ-1,3-thiocyanate group forming zigzag chains along the c-axis of the unit cell.     

Tin,palladium and platinum derivatives of 1,1′-bis(diphenylphosphine)ferrocene. Crystal and molecular structures of 1,1′- bis-(diphenylphosphine)ferrocenedichloropalladium(II) and of 1,1′-bis(diphenylphosphine)ferrocenedichloroplatinum(II)

Summary Ten derivatives of 1,1-bis(diphenylphosphine)ferrocene (BDPF) are described in this paper. The first three, [BDPF·SnCl₄] (1), [BDPF·MeSnCl₃] (2) and [BDPF·PhSnCl₃] (3), present the two phosphorus atoms of the ligand directly bonded to a Sn centre. Two others, [BDPF-PdCl₂ (4) and [BDPF·PtCl₂] (5), similarly have the ligand BDPF acting as a bidentate species towards a transition metal. The crystal and molecular structures of (4) and (5) are presented here. Two other BDPF complexes were obtained with Pd and Pt, with the transition metals in the zerovalent state, namely [Pd(BDPF)₂] (6) and [Pt(BDPF)₂] (7). Finally, three trimetallic complexes are also described; [BDPF·Pd(-Cl)₂SnCl₂] (8), [BDPF· Pt(-Cl)₂SnCl₂] (9) and [BDPF·PdClSnCl₃] (10).     

Syntheses,crystal structures,and luminescence of coordination polymers [Cu(μ-Br)(μ-phpzm)] n , [{Cu(μ-SCN)}2(μ-phpzm)] n,and [(phpzm)Cu(μ-CN)] n (phpzm = bis(4-phenylpyrazol-1-yl)methane)

Solvothermal reactions of CuX (X?=?Br, SCN, CN) with bis(4-phenyl-pyrazol-1-yl)methane (phpzm) gave two 2-D coordination polymers, [Cu(μ-Br)(μ-phpzm)] _n (1) and [{Cu(μ-SCN)}₂(μ-phpzm)] _n (2), and a 1-D coordination polymer, [(phpzm)Cu(μ-CN)] _n (3). Compounds 1–3 were characterized by elemental analysis, IR spectra, and X-ray crystallography. Compounds 1 and 2 have 2-D networks in which split-stair [Cu(μ-Br)] _n chains (1) or staircase-like [Cu(μ-SCN)] _n double chains (2) are linked by μ-phpzm bridges. Compound 3 consists of a zigzag chain formed by linking [Cu(phpzm)] fragments via cyanide bridges. Luminescence properties of 1–3 along with phpzm in the solid state at ambient temperature were also investigated.     

Novel di-μ-chloro-bis[chloro(4,7-dimethyl-1,10-phenanthroline)cadmium(II)] dimer complex: synthesis, spectral, thermal, and crystal structure studies

A novel di-μ-chloro-bis[chloro(4,7-dimethyl-1,10-phenanthroline)cadmium(II)] dimer complex has been prepared by reacting CdCl₂·2.5H₂O with 4,7-dimethyl-1,10-phenanthroline (dmphen) ligand. The complex was characterized on the basis of elemental analysis, FAB-MS, IR, UV–visible, ¹H, and ¹³C NMR spectroscopy, TG/DTA, and X-ray single-crystal diffraction studies. The Cd(II) ions in [CdCl₂(C₁₄H₁₂N₂)]₂ are coordinated to three Cl atoms with the centrosymmetric dimer bridged through the Cl atoms and two N atoms in a slightly distorted square-pyramidal disposition. Several hydrogen bonds formed between the terminal Cl atoms and H-Me/H-Ph groups may stabilize the structure in the dimer form.     

Silver(I) bromide complexes of the rigid diphosphanes 1,2-bis(diphenylphosphano)benzene (dppbz) and 4,5-bis(diphenylphosphano)-9,9-dimethyl-xanthene (xantphos): Crystal structures of [Ag(μ2-Br)(dppbz)]2, [AgBr(xantphos)] and [AgBr(xantphos)(py2SH)]

Reaction of silver(I) bromide with equimolar amounts of the rigid diphos ligands 1,2-bis(diphenylphosphano)benzene (dppbz) and 4,5-bis(diphenylphosphano)-9,9-dimethyl-xanthene (xantphos) in acetone and acetonitrile led to the corresponding chelates [Ag(μ₂-Br)(dppbz)]₂ (1) and [AgBr(xantphos)] (2). Treatment of 1 and 2 with pyridine-2-thione (py2SH) in ethanol gave the mixed-ligand complexes [AgBr(dppbz)(py2SH)] (3) and [AgBr(xantphos)(py2SH)] (4), respectively. Compounds 1, 2 and 4 have been characterized by X-ray diffraction, establishing distorted tetrahedral or trigonal planar coordination geometries of the silver atoms.     

Synthesis and Characterization of Nitrato-Triamine-Metal(II) Complexes. Conglomerate Crystallization Part 55. Crystal Structure of [Ni(dien)(O2NO)(ONO2)] (I), {[Cu(dien)-(μ-ONO2)]NO3}∞ (II), [Zn(dien)(O2NO)(ONO2)] (III), [Ni(Medpt)(O2NO)(ONO2)] (IV) and [Cu(Medpt)(ONO2)2] (V)

In absolute ethanol and in the presence of triethylorthoformate, reactions of metal(II) nitrates with linear tridentate amines afforded metal complexes of the formula M(NNN)(NO₃)₂, where M = Ni²⁺, Cu²⁺ and Zn²⁺, and NNN = dien and Medpt. The compounds fall into three categories in accordance with their stereochemistry and mode of binding of the nitrato ligands. Compounds I, [Ni(dien)(O₂NO)(ONO₂)] and III, [Zn(dien)(O₂NO)(ONO₂)] are isomorphous and isostructural. They crystallize in the monoclinic space group P2₁/n with nearly identical cell constants. The stereochemistry of these two compounds is such that the terdentate dien ligand forms a fac MN₃ moiety with the two oxygens of the bidentate nitrato ligand trans to the terminal NH₂. These ligands form the base of the octahedral arrangement in which the sixth position, trans to the secondary nitrogen of the dien, is an oxygen of the monodentate nitrato ligand. Compound IV, [Ni(Medpt)(O₂NO)(ONO₂)] falls into the same category as I and III despite the fact that the two rings in the Ni-Medpt moiety are six-membered rings, unlike those in compounds I and III which are five-membered rings. Nevertheless, the nickel-amine arrangement is fac. The bidentate nitrato-oxygens are trans to the terminal NH₂ of the amine ligand, and the oxygen of the monodentate nitrato ligand is trans to the tertiary amine-nitrogen. Such stereochemistry is prevalent for nickel and zinc compounds. Interestingly, compound IV crystallizes as a conglomerate (space group P2₁2₁2₁). Compound II, {[Cu(dien)(μ-ONO₂)]NO₃}_∞ belongs to the second category and has a polymeric structure. The repeating fragment in the polymeric chain is a Cu(dien)-O fragment with the monodentate nitrato ligand occupying an equatorial position of the base. A second oxygen of the equatorial nitrate becomes an axial ligand for an adjacent Cu-N₃O fragment. In this way the substance propagates into an infinite chain. The repeating unit has an effective square pyramidal, five-coordinate, configuration. Finally, the compound crystallizes as a racemate. The second nitrate necessary for charge compensation of this copper(II) compound is ionic and its function is to hold the infinite chains of the lattice. The third category represented by compound V, [Cu(Medpt)(ONO₂)₂] contains two molecules in the asymmetric unit of the racemic lattice (monoclinic, space group P2₁/a). The structure of Cu-Medpt is unlike that of IV in that both species present in the asymmetric unit have the amine ligand in a mer configuration which together with a monodentate oxygen of a nitrato ligand form a base plane of a square pyramid. The fifth ligand of both Cu²⁺ ions is a second monodentate nitrato ligand. The stereochemical differences between the two Cu²⁺ ions are insignificant for the Cu-Medpt fragment, which share the same conformation and configuration. The major difference between the two species is the torsional angles defined by the Cu-O-N-O angles. The difference arises from variation in the hydrogens of the primary amine moieties selected by nitrato-oxygens to form intramolecular hydrogen bonds. Finally, there is a little variation in the equatorial Cu-ONO₂ stereochemistry because of steric hindrance, imposed by the Medpt, preventing large torsional angles by these nitrato ligands. This is evident by comparing the two copper species shown in Finally, nitrate-to-Br ligand exchange was found to take place when KBr pellets are prepared for IR spectral measurements.     

Crystal and molecular structure of dicopper bis-(3-amino-5-methylisoxazole)tetraacetate [Cu2(μ-OCOCH3)2L2]

It was established by X-ray diffraction analysis that in the dimer complex of 3-amino-5-methylisoxazole (L) [ Cu₂(μ-OCOCH₃)₄L₂ ] the coordination bond is localized at the endocyclic pyridine type N atom. Arguments are given against other possible types of coordination in aminoisoxazole complexes conjectured from IR spectroscopy data in a number of publications. The dimer structure of the complex agrees with antiferromagnetic data (2J = -280 cm^-1 ). Translated fromZhurnal Strukturnoi Khimii, Vol. 41, No. 3, pp. 572-580, May–June, 2000.     

Synthesis and Crystal Structure of [Cd(NBA)(μ_3-OH)(4,4′-bipy)_(1/2)]_n

A new cadmium polymer [Cd(NBA)(μ3-OH)(4,4′-bipy)1/2]n 1 (NBA = m-nitrobenzoic acid and 4,4′-bipy = 4,4-bipyridine) has been synthesized by hydrothermal reaction. Its structure was determined by single-crystal X-ray diffraction method, and characterized by elemental analysis and IR spectrum. The crystal is of monoclinic, space group C2/c, with a = 15.6912(9), b = 25.9394(15), c = 6.7332(4) ′, β = 114.7700(10)°, V = 2488.4(3) 3, C12H9CdN2O5, Mr = 373.61, Z = 8, Dc = 1.995 g/cm3, μ = 1.776 mm-1, F(000) = 1464, R = 0.0411 and wR = 0.1128 for 2130 observed reflections (I > 2σ(I)). X-ray diffraction studies reveal that the compound features a layered structure, in which 4,4′-bipy ligands bridge Z type of double chains [Cd(μ3-OH)]n and NBA ligands locate at the two sides of the layer. The π-π interactions between the benzene rings of NBA ligands of two adjacent layers lead to the 3D framework.     

Crystal structures of the selenium- and bromo-bridged copper(I) dimers [Cu2(μ2-Br)2(SePPh3)2 · (NCCH3)2] and [Cu2I2(μ3-dppm-Se,Se)2] · 2CH3CN

Reactions of copper(I) halides with Se-donor ligands, namely, triphenylphosphine selenide (Ph₃PSe) and bis(diphenylselenophosphinyl)methane (dppm-Se,Se) yielded bromo-bridged [Cu₂(μ₂-Br)₂(SePPh₃)₂(NCCH₃)₂] (1), and selenium-bridged, [Cu₂I₂(μ₃-dppm-Se,Se)₂]?· 2CH₃CN (2) dimers, whose crystal structures are described. Acetonitrile stabilizes 1 by coordinating and helps to stabilize the packing in crystals of 2.     

μ-Amido complexes of ruthenium carbonyl. Asymmetric versus symmetric bridging preference of the monodeprotonated derivatives of 1,2-arenediamines. Crystal structure of [Ru3(μ-H)(μ-H3N2-4,5-Me2-1,2-phenylene)]

[Ru₃(CO)₁₂] reacts with 1,2-arenediamines (H₄N₂arene), under CO, to give the very asymmetric clusters [Ru₃(μ-H)(μ-H₃N₂arene)(CO)₉] (arene = 1,2-phenylene (1a) or 4,5-Me₂-1,2-phenylene (1b)) in which the three Ru atoms bear two, three, and four CO ligands, respectively. Under similar conditions, reaction of [Ru₃(CO)₁₂] with 1,8-diaminonaphthalene (H₄N₂naph) leads to break up of the cluster framework to give the binuclear ruthenium(I) compound [Ru₂(μ-H₂N₂naph)(CO)₆] (3). The crystal structure of compound 1b has been determined by an X-ray diffraction study.     

Mono- and dinuclear palladium(II) compounds containing nitrogen ligands. Crystal and molecular structure of [Pd(N,C-dmba)(NCO)(2,3-lut)] and [Pd(H2CCOMe)Cl(2,2′-bipy)]

The cyanate-bridged cyclopalladated compound [Pd(N,C-dmba)(-NCO)]₂ (1)(dmba = PhCH₂NMe₂) reacts in CH₂Cl₂ with 2,3-lutidine (2,3-lut), 3,4-lutidine (3,4-lut), 2,2-bipyridine (2,2-bipy) and 4,4-bipyridine (4,4-bipy), to give [Pd(N,C-dmba)(NCO)(2,3-lut)](2), [Pd(N,C-dmba)(NCO)(3,4-lut)](3), [{Pd(N,C-dmba)(NCO)}₂(-2,2-bipy)]· CH₂Cl₂ (4) and [{Pd(N,C-dmba)(NCO)}₂(-4,4-bipy)]· CH₂Cl₂ (5), respectively. The compounds were characterized by elemental analysis, i.r. and n.m.r. spectroscopy and also by t.g.a. The i.r. spectra of (2–5) display typical bands of monodentate N-bonded cyanate groups, whereas the n.m.r. data of (4) are consistent with the presence of a bridging 2,2-bipyridine ligand. Complex (4) decomposes slowly in acetone. One of the products formed, [Pd(H₂CCOMe)Cl(2,2-bipy)](6), was characterized by X-ray diffraction. As inferred from the t.g.a., the thermal stability decreases in the order:[{Pd(N,C-dmba)(NCO)}₂(-4,4-bipy)].CH₂Cl₂ (5) > [Pd(N,C-dmba)(2,3-lut)(NCO)](2)=[Pd(N,C-dmba)(3,4-lut)(NCO)](3) > [{Pd(N,C-dmba)(NCO)}₂(-2,2-bipy)]· CH₂Cl₂ (4). According to thermal analysis and X-ray diffraction patterns compounds (2–3) decompose into metallic palladium Pd(0), whereas (4–5) decompose with the formation of PdO. The X-ray crystal and molecular structure of [Pd(N,C-dmba)(NCO)(2,3-lut)](2) was determined. The lutidine unit is perpendicular to the coordination plane.     

Novel polyselenidoarsenate and selenidoarsenate: solvothermal synthesis and characterization of [Co(phen)3][As2Se2(μ-Se3)(μ-Se5)] and [Co(phen)3]2[As8Se14

Novel cobalt polyselenidoarsenate [Co(phen)(3)][As(2)Se(2)(μ-Se(3))(μ-Se(5))] (1; phen = 1,10-phenanthroline) was methanolothermally synthesized by the reaction of CoCl(2), As(2)O(3), and Se templated by phen in a CH(3)OH solvent at 130 °C. The same reaction in a H(2)O solvent yielded cobalt selenidoarsenate [Co(phen)(3)](2)[As(8)Se(14)] (2). In 1, the AsSe(+) units are alternately joined by the μ-Se(3)(2-) and μ-Se(5)(2-) bridging ligands to form a novel helical polyselenidoarsenate chain [As(2)Se(2)(μ-Se(3))(μ-Se(5))(2-)](∞). In 2, eight pyramidal AsSe(3) units are connected via corner sharing into the new member of the selenidoarsenate aggregate [As(8)Se(14)](4-) with a condensation grade of 0.571, which represents the first discrete selenidoarsenate(III) with a condensation grade of above 0.50. The octahedral complex [Co(phen)(3)](2+) is formed in situ to act as a countercation in compounds 1 and 2. 1 and 2 exhibit steep absorption band gaps at 2.09 and 2.16 eV, respectively.     

Structural isomerism of propionato copper(II) complex: crystal and molecular structure of tetrakis(μ-o-propionato)bis(methyl 3-pyridyl-N-carbamate)dicopper(II) at 190 K

The crystal and molecular structure of tetrakis(μ-o-propionato)bis(methyl 3-pyridyl-N-carbamate)dicopper(II) at 190 K was determined by X-ray analysis. The internuclear Cu⋯Cu distance is 2.6395(3) Å. CuO bond lengths are 1.961(1), 1.9678(9), 1.9828(9) and 1.9979(9) Å and CuN bond length is 2.165(1) Å. The non-bonding Cu(II)⋯Cu(II) contacts for nine binuclear Cu(II) propionates and hexacoordination of Cu(II) ion in the structure of [Cu(CH₃CH₂COO)₂(mpc)₂]0.25H₂O (mpc=methyl 3-pyridyl-N-carbamate) is consistent with the bond–valence sum model.     

Alkylimido osmium(VI) and ruthenium(VI) porphyrins. Crystal and molecular structures of Os(TTP)(O)(NBu~t)·EtOH and Os(4-Cl-TPP)(NBu~t)_2

Oxo(tert-butylimido) or bis(tert-butylimido)osmium(VI) porphyrins Os(Por)(O)(NBut) and Os(Por)(NBut)2, [Por=meso-tetrakis(p-tolyl)porphyrinato (TTP) and meso-tetrakis(4-chlorophe-nyl)porphyrinato (4-Cl-TPP)] were synthesized by air oxidation of bis(tert-butylamme)osmium(II) porphyrins [Os(Por)(H2NBut)2 (Por=TPP, 4-Cl-TPP], depending on whether tert-butylamine is present. The bis(tert-butylamine)ruthenium(II) porphyrins [Ru(Por)(H2NBut)2, Por=TTP, 4-Cl-TPP] can undergo bromine oxidation to give oxo(tert-butylimido)ruthenium(VI) complexes in quantitative yields. All these new complexes were characterized by 1H NMR, UV-Visible and IR spectroscopy. The X-ray crystal structures of Os(TTP)(O)(NBut).EtOH and Os(4-Cl-TPP)(NBut)2 have been determined. Crystal data: for Os(TTP)(O)(NBut).EtOH: monoclinic, space group P21/c, a=1.3546(6) nm, b=2.3180(3) nm, c=1.6817(3) nm, B=90.84(2), V=527.97(1) nm3, Z=4. The Os=O and Os=NBut distances in Os(TTP)(O)(NBut).EtOH are 0.1772(7) nm and 0.1759(9) nm, respectively. The av