Crystal and molecular structure of (η3-allyl)carbonylchlorobis(dimethylphenylphosphine)- iridium(III) hexafluorophosphate, [Ir(η3-C3H5)Cl(CO)(P(CH3)2(C6H5))2][PF6

The structure of (η³-allyl)carbonylchlorobis(dimethylphenylphosphine)-iridium(III) hexafluorophosphate, [Ir(η³-C₃H₅)Cl(CO)(P(CH₃)₂(C₆H₅))₂][PF₆], has been determined from three-dimensional X-ray data to add support for a proposed mechanism of the oxidative addition of allyl halides to IrX(CO)(PR₃)₂ (X = halide). The compound crystallizes in space group C⁵_2h-P2₁/c with four formula units in a cell of dimensions a = 11.027(1), b = 12.230(2), c = 19.447(5) Å, and β = 103.16(2)⁰. Least-squares refinement of the structure has led to a value of the conventional R index (on F) of 0.066 for the 3018 independent reflections having F²₀>3—(F²₀). The crystal structure consists of discrete, monomericions. The hexafluorophosphate anion is disordered. The coordination geometry around the iridium atom may be described as octahedral, with the chloro ligand trans to the carbonyl group and each phosphorus atom trans to a terminal carbon of the allyl group. Structural parameters: Ir—P = 2.366(4), 2.347(3);Ir—Cl = 2.389(3); Ir—C(allyl) = 2.28(1), 2.24(1),2.25(1); Ir—C (carbonyl) = 1.85(1) Å; P—Ir—P = 105.7(1); C(terminal)—Ir—C(terminal) = 66.2(8); C—C—C = 125(2)^o. The allyl group makes an angle of 126^o with the P—Ir—P plane. Correlations between geometric structure and number of d electrons are noted among several M—C₃H₅-complexes, and are interpreted in the light of theoretical models of the M—C₃H₅- bond.     

[(C6H5)4P]2[Mo(NO)(ONC(CH3)2)(NCS)4], ein Komplex mit einem side-on gebundenen Oximato-Liganden; Kristall- und Molekülstruktur

[(C₆H₅)₄P]₂[Mo(NO)(ONC(CH₃)₂)(NCS)₄], a Complex Having a Side-on Coordinated Oximato Ligand; Crystal and Molecular Structure The structure of the title compound 1 was determined from single-crystal X-ray data 1 crystallizes in the triclinic space group P1 . Mo has a pentagonal-bipyramidal coordination sphere. The oximato-ligand is side-on bonded in the equatorial plane. (Mo? N and Mo? O bond lengths: 2.086(8) and 2.090(6) Å, respectively) (R = 0.082; R_w = 0,077).     

The crystal structure of Cu4(PO4)2O

Cu₄(PO₄)₂O crystallizes in the space group $\text{P}\text{1}$ with a = 7.5393(8) Å, b = 8.1021(9) Å, c = 6.2764(8) Å, α = 113.65(1)°, β = 98.42(1)° and γ = 74.19(1)°. The structure was refined by full-matrix least-squares techniques using automatic diffractometer data to R = 0.046 (R_w = 0.056). Four unique copper atoms are in six, five-, and four-coordinated polyhedra which are linked together to form a three-dimensional network. The structure is best described in terms of a cubic close-packed array of oxygen atoms with one-tenth of the possible anion sites vacant.     

(η5‐Cyclo­penta­dienyl)(p‐fluoro­phenoxo)(nitro­syl)(tri­methyl­silyl­methyl)­molybdenum(II)

The title complex, [Mo(C₅H₅)(C₆H₄FO)(C₄H₁₁Si)(NO)], is formed by reacting CpMo(NO)(CH₂SiMe₃)₂, where Cp is cyclo­penta­dienyl, with one equivalent of p‐FC₆H₄OH. The complex exhibits the expected piano‐stool molecular structure, with a linear nitro­syl ligand [Mo—N—O 168.2 (2)°] having Mo—N and N—O distances of 1.764 (2) and 1.207 (3) Å, respectively. The phenoxo Mo—O distance of 1.945 (2) Å is suggestive of some multiple‐bond character.     

The 13C and 119Sn NMR spectra of some four- and five-coordinate tri-n-butyltin(IV) compounds

Silver tetrafluoroborate reacts with Cl(bipy)(CO)₂(η³-C₃H₅)Mo in CH₂Cl₂ to give the dimeric cation, (μ-Cl)[(bipy)(CO)₂(η³-C₃H₅)Mo]₂⁺, isolated as the crystalline BF₄^? salt with CH₂Cl₂ of solvation (5). Complex 5 crystallizes in the triclinic system (space group P$\text{1}$, No. 2) with cell parameters: a 11.831(2), b 10.142(3), c 15.618(3) Å; α 93.96(2), β 104.33(2), γ 91.41(2)°, V 1809.5(8) ųZ = 2, ?_calc 1.60 g cm^?3. Full matrix refinement with all but three atoms anisotropic converged at R₁ = 0.057 and R₂ = 0.073 based on 3742 reflections with I > 30(1). The two halves of the dimer are connected by a single chloride bridge (Mo-Cl 2.554(3), 2.519(3) Å, Mo-Cl-Mo 134.0(1)°). The η³-allyl group is oriented so that its open face points toward the two cis-carbonyl groups, a feature common to all L₂X(CO)₂Mo(η³-allyl) structures determined to date. A molecular orbital analysis shows that this rotational preference of the allyl group has its roots in the strong π-bonding character of the carbonyls. The MO analysis also provides a rationale for regioselectivity observed in the reactions of various η³-allyl complexes with nucleophiles. In particular, the factors which determine whether the terminal carbons are attacked (giving olefin) or whether the central carbon is attacked (giving a metallacyclobutane) are exposed.     

The crystal structure of cesium azidotrimethyl-aluminate

The crystal structure of Cs[Al(CH₃)₃N₃] has been determined from single-crystal X-ray diffraction data collected by counter methods. Cesium azidotrimethylaluminate crystallizes in the orthorhombic space group Pbcm with cell dimensions a = 8.027 (9), b = 10.504 (9), c = 10.307 (9) Å, and ?_calc = 1.89 g cm^?1 for Z = 4. Least-squares refinement gave a final R value of 0.046 for 556 independent observed reflections. The anion lies on a crystallographic mirror plane; the AlN bond length is 1.97 (1) Å. Within the azide ion the two nitrogen-nitrogen lengths are distinctly different: 1.13 (2) and 1.21 (2) Å.     

Synthesis, structure, properties, volatility, and thermal stability of molybdenum(II) and tungsten(II) complexes containing allyl, carbonyl, and pyrazolate or amidinate ligands

Treatment of M(allyl)(Cl)(CO)₂(py)₂ (M = Mo, W) with 1 equiv. of potassium pyrazolates in tetrahydrofuran at −78 °C afforded M(allyl)(R₂pz)(CO)₂(py)_n (R₂pz = 3,5-disubstituted pyrazolate; n = 1, 2) in 68-81% yields. X-ray crystal structure analyses of Mo(allyl)((CF₃)₂pz)(CO)₂(py)₂ and W(allyl)(tBu₂pz)(CO)₂(py) revealed η¹- and η²-coordination of the (CF₃)₂pz and tBu₂pz ligands, respectively. Analogous treatment of Mo(allyl)(Cl)(CO)₂(NCCH₃)₂ with 1 equiv. of tBu₂pzK in tetrahydrofuran at −78 °C afforded [Mo(allyl)(tBu₂pz)(CO)₂]₂ in 79% yield. An X-ray crystal structure analysis of [Mo(allyl)(tBu₂pz)(CO)₂]₂ showed a dimeric structure bridged by two μ-η²:η¹-tBu₂pz ligands. Treatment of M(allyl)(Cl)(CO)₂(py)₂ with 1 equiv. of lithium 1,3-diisopropylacetamidinate or lithium 1,3-di-tert-butylacetamidinate in diethyl ether at −78 °C afforded M(allyl)(iPrNC(Me)NiPr)(CO)₂(py) and M(allyl)(tBuNC(Me)NtBu)(CO)₂(py), respectively, in 68-78% yields. The new complexes were characterized by spectral and analytical methods and by X-ray crystal structure determinations. M(allyl)(iPrNC(Me)NiPr)(CO)₂(py) adopt pseudo-octahedral geometry about the metal centers, with the 1,3-diisopropylacetamidate ligand nitrogen atoms spanning one axial site and one equatorial site of the octahedron. By contrast, M(allyl)(tBuNC(Me)NtBu)(CO)₂(py) adopt pseudo-octahedral structures in which the two 1,3-di-tert-butylacetamidinate ligand nitrogen atoms span two equatorial coordination sites. Sublimation of M(allyl)(tBuNC(Me)NtBu)-(CO)₂(py) at 105 °C/0.03 Torr afforded ?7% yields of M(allyl)(tBuNC(Me)NtBu)(CO)₂, along with sublimed M(allyl)(tBuNC(Me)NtBu)(CO)₂(py). W(allyl)(tBuNC(Me)NtBu)(CO)₂ exists in the solid state as a 16-electron complex with distorted square pyramidal geometry. Many of the new complexes undergo dynamic ligand site exchange in solution, and these processes were probed by variable temperature ¹H NMR spectroscopy. The volatilities and thermal stabilities were evaluated to determine the potential of the new complexes for use as precursors in thin film growth experiments.     

Absolute configurations of organometallic compounds : V. X-ray study of (−)578-(η5-C5H5)Mo(CO)2SC(CH3NR′ with R′ = (S-CH(CH3)(C6H5)

The structure and absolute configuration of the thioamido complex (?)₅₇₈-(η⁵-C₅H₅Mo(DO)₂SC(CH₃NR′ with R′ = (S)CH(CH₃)(C₆H₅) have been determined by single-crystal X-ray diffraction. The substance crystallizes in the orthorhombic system; space group P2₁2₁2₁ with cell constants of a = 8.314(1), b = 9.020(1), and c = 22.352(2) Å, and Z = 4 molecules/unit cell. The absolute configuration was determined using Bijvoet's method. Refinement of the data using the anomalous scattering contributions of Mo and S yields a final R(F = 0.036 for 2715 independent reflections having I > 3σ(I). The distorted square pyramidal coordination of the Mo atom is defined by two carbonyl carbons and the S and N atoms of the thioamido ligand occupying the four basal plane sites and the five carbons of the η⁵-C₅C₅ ligand in the axial position. The Mo—ligand distances and most of the bond lengths and angles within the ligands are normal and compare closely with those of recent structure determinations. However, the distances and angles within the thioacetamide ligand show, distinctly, the effect of chelate binding to the Mo atom. In particular, the angles at the central thioacetamide carbon differ markedly from those of free thioacetamide and monodentate, S-bound metal thioacetamido complexes. The Mo atom is 1.041 Å above the plane formed by the four basal ligands. The conformation of the (S)-α-phenylethyl group with respect to the ligand plane, defined by the thioamido system and the Mo atom, is discussed. The configuration at the metal atom in the (?)₅₇₈-isomer of (η⁵-C₅H₅)Mo(CO)₂SC(CH₃)NR′ is specified as (S).     

The crystal structure of Co6C(CO)12E2 (E = Se) and its relevance to the vibrational spectra of the species E = S,Se

Co₆C(CO)₁₂Se₂ crystallizes in the monoclinic system, space group Cc with a = 16.365(4) Å, b = 9.429(2) Å, c = 17.479(5) Å, β = 122.75(2)°, Z = 4 and (Mo — K_a) = 0.71070 Å. The final reliability indices are R = 0.051 and R_W = 0.048 for 2081 observed reflections having F > 4.0σ(F). The molecule consists of a Co₆ trigonal prism with the triangular faces capped by selenium atoms. Each cobalt is bonded to two terminal CO groups. A carbon atom is embedded at the centre of the Co₆ prism. The Raman spectra of polycrystalline samples of this compound and of the sulphur analogue have been recorded. These, together with the corresponding infrared data, can only be understood in terms of a dominant intermolecular coupling on the ν(Co—E) modes (E = S, Se). The origin of this coupling is the close contact between neighbouring clusters in one distinct direction which gives rise to a chain of molecules in the crystal. The significant effect of these oriented close contacts on the vibrational modes is demonstrated.     

Research on in part “loosely” coordinated trinuclear molybdenum cluster compounds — the synthesis and crystal structure of {Mo3(μ3-S)(μ-S)3[S2P(OEt)2]4 ṁ P(C6H5)3} (0.86CH2Cl2)

The synthesis and crystal structure of novel trinuclear molybdenum cluster compound with somewhat “loose” coordination site {Mo₃(μ₃-S)(μ-S)₃[S₂P(OEt)₂l₄ ? P(C₆H₅)₃} ? (0.86 CH₂C1₂) have been reported. The cluster crystallizes in the space group with two molecules in a unit cell whose parameters are a=10.472(4), b=14.375(2), c=21.695(3)Å; α=74.04(1)°, β=76.50(2)°, γ=72.22 (2)°, V=2950ų and D_o=1.693 g ? cm^?3. On the basis of 4840 independent reflections with I≥2σ(I), the structure was solved by heavy atom method and Fourier method and refined by full-matrix least-squares techniques to a final R=0.058. The distances between Mo atoms in this cluster are 2.731(1), 2.748(1) and 2.753(1)Å respectively. The meat value of Mo—Mo bond lengths is slightly shorter than those in other trinuclear Mo clusters with “loosely coordinated” site. In addition, the PPh₃ ligand is loosely coordinated to one Mo atom in direction opposite to the μ₃-S with Mo—P bond length of 2.647(3)Å. This is different from the other structurally analogous clusters, in which the loosely coordinated ligand is trans to μ₂-S. A summary of Mo—Mo and Mo—L bonding for such clusters is given.     

The crystal and molecular structure of bis(pentamethylcyclopentadienyl)dichlorotitanium(IV)

The structure of bis(pentamethylcyclopentadienyl)dichlorotitanium(IV) has been investigated by single-crystal X-ray diffraction techniques. [η-C₅(CH₃)₅]₂TiCl₂ crystallizes in the orthorhombic space group P2₁2₁2₁ with cell dimensions a = 10.816(1), b = 8.132(1), c = 22.259(1) Å; Z = 4. Full matrix, least-squares refinement converged to a final R index of 0.032 based on 1429 reflections. The configuration about the titanium atom is a distorted tetrahedron comprised of the two chlorine atoms and the centroids of the two η-cyclopentadienyl rings. Several ring methyl groups are bent considerably out of the cyclopentadienyl plane and away from the titanium atom. These out-of-plane deviations are attributable to chlorine—methyl crowding and methyl—methyl contacts between the two rings.     

Di‐μ‐methoxy‐bis[(η5‐cyclopentadienyl)(nitrosyl‐κN)(trimethylsilylmethyl)molybdenum(II)]

The title complex, [Mo₂(C₅H₅)₂(CH₃O)₂(C₄H₁₁Si)₂(NO)₂], is formed in high yield by treating [CpMo(NO)(CH₂SiMe₃)₂] (Cp is cyclo­penta­dienyl) with methanol. The nitro­syl ligands are nearly linear [O—N—Mo 170.1 (4) and 170.1 (5)°], with short Mo—N bonds [1.769 (4) and 1.776 (4) Å] and long N—O bonds [1.216 (5) and 1.201 (4) Å]. The central four‐membered Mo₂O₂ ring exhibits an average Mo—O bond length of 2.15 Å.     

SYNTHESIS OF A DINUCLEAR YLID COMPLEX DERIVED FROM P(OPh)3: CRYSTAL STRUCTURES OF [Cp2Fe2(CO)2(μ-CO) (μ-CHP(OPh)3)+][BF4 −] AND [Cp2Fe2(CO)2 (μ-CO)(μ-CHPPh3)+][BF4 −]

Abstract

[Cp₂Fe₂(CO)₂(μ-CO)(μ-CHP(OPh)₃)⁺][BF^? ₄] crystallizes in the centrosymmetric monoclinic space group P2₁/n with a = 12.553(7) Å, b = 16.572(11) Å, c = 15.112(8) Å, β = 100.00(4)°, V = 3096(3) ų and D(calcd.) = 1.579 g/cm³ for Z = 4. The structure was refined to R(F) = 5.83% for 1972 reflections above 4σ(F). The cation contains two CpFe(CO) fragments linked via an iron—iron bond (Fe(1)—Fe(2) = 2.544(3)Å), a bridging carbonyl ligand (Fe(1)—C(4) = 1.918(1) Å, Fe(2)—C(4) = 1.946(12)Å) and a bridging CHP(OPh)₃ ligand (Fe(1)—C(1) = 1.980(9)Å, Fe(2)—C(1) = 1.989(8)Å). Distances within the μ-CHP(OPh)₃ moiety include a rather short carbon—phosphorus bond [C(1)—P(1) = 1.680(10)Å] and P—O bond lengths of 1.550(7)–1.579(6)Å. The crystal is stabilized by a network of F…H—C interactions involving the BF^? ₄ anion.

[Cp₂Fe₂(CO)₂(μ-CO)(μ-CHPPh₃)⁺][BF^? ₄], which differs from the previous compound only in having a μ-CHPPh₃ (rather than μ-CHP(OPh)₃) ligand, crystallizes in the centrosymmetric monoclinic space group P2₁/c with a = 11.248(5)Å, b = 13.855(5)Å, c = 18.920(7)Å, β = 96.25(3)°, V = 2931(2)ų and D(calcd.) = 1.559 g/cm³ for Z = 4. This structure was refined to R(F) = 4.66% for 1985 reflections above 4σ(F). Bond lengths within the dinuclear cation here include Fe(1)-Fe(2) = 2.529(2)Å, Fe(1)—C(3) = 1.904(9) Å and Fe(2)—C(3) = 1.911(8) Å (for the bridging CO ligand) and Fe(1)—C(1P) = 1.995(6) Å and Fe(2)—C(1P) = 1.981(7) Å (for the bridging CHPPh₃ ligand). Distances within the μ-CHPPh₃ ligand include a longer carbon—phosphorus bond [C(1P)—P(1) = 1.768(6)Å] and P(1)—C(phenyl) = 1.797(7)–1.815(8) Å.     

Synthesis and crystal structure of a cubanelike tetranuclear molybdenum cluster compound {Mo4)(μ3-S)3)(μ3-O)[S2P(OEt)2]6} · 3CH3CN

A tetranuclear molybdenum cluster compound {Mo₄(μ₃-S)₃(μ₃-O)[S₂P(OEt)₂]₅} · 3CH₃CN was obtained by the reaction of MoCl₃ · 3H₂O with P₂S₅ in ethanol and then recrystallization from acetonitrile. The compound crystallizes in the trigonal system belonging to the space group R3 with the following cell dimensions: a = b = c = 12.852 (3) Å, α = β = γ = 108.37 (2)°, V =1697.3ų Z = 1, D_c. = 1.693g.cm^?3. The structure was solved by heavy atom method and refined by full-matrix least-squares to R = 0.072 for 1781 reflections with I≥3σ(I). The results of the structure determination indicate that the cluster skeleton possesses a cubanelike cluster core formed by four Mo atoms located in a distored tetrahedron with three S atoms and one O atom as its triple bridging atoms. There are two sets of bond distances, i.e. 2.700 (1) and 2.831(1) Å in the six Mo—Mo bonds. Taking the Mo cluster core as a whole, it has a formal oxidation state of +14, leaving ten electrons to form the metal-metal bonds. Thus each Mo—Mo bond has an average bond order of 5/6.     

The crystal structure of a complex cerium(III) molybdate; Ce6(MoO4)8(Mo2O7)

Ce₆Mo₁₀O₃₉ crystallizes in the triclinic system with unit-cell dimensions (from single-crystal data) a = 10.148(5), Å, b = 18.764(6), Å, c = 9.566(5), Å, α = 103.12(7)°, β = 78.07(7)°, γ = 107.69(7)°, and space group $\text{P}\text{1}\text{, z = 2}$. The structure was solved using direct methods with 3113 countermeasured reflections (MoKα radiation), and refined using Fourier and least-squares techniques to a conventional R of 0.039 (ωR = 0.047). Ce₆Mo₁₀O₃₉ has a structure that consists of isolated MoO₄ tetrahedra together with one corner-shared pair of tetrahedra, linked to irregular eight-coordinate Ce(III) polyhedra. The average MoO distance of 1.77 Å, and average CeO distance of 2.52 Å are in good agreement with previously reported values.     

Yttrium(III) complex with 1,10-phenanthroline: Crystal structure and spectroscopic studies

YCl₃·6H₂O reacts with 1,10-phenanthroline (phen) to yield a complex of 1:2 yttrium:ligand stoichiometry. The yttrium(III) complex is characterized by the elemental analysis, UV-Vis, IR as well as the X-ray diffraction analysis. The crystal of [Y(phen)₂Cl(H₂O)₃]Cl₂·H₂O obtained from a methanol solution crystallizes in the triclinic system, space group P 337-1, Z = 2, a = 10.3236(4) Å, b = 10.4566(4) Å, c = 12.5270(5) Å, α = 97.354(2)°, β = 108.740(2)°, γ = 93.458(2)°, R _int = 0.046. The Y(III) ion is eight-coordinated by four nitrogen, three oxygen atoms and one chlorine atom.     

Synthesis and X-ray diffraction studies of chiral nickel(II), zinc(II), manganese(II), and cobalt(II) complexes with C 2-symmetric 2,6-bis[4′-(R)-ethoxyoxazolin-2′-yl]pyridine

Chiral nickel(II), zinc(II), manganese(II), and cobalt(II) complexes with C ₂-symmetric 2,6-bis[4′-(R)-ethoxyoxazolin-2′-yl]pyridine were prepared, the single crystal of nickel(II) complex, [Ni((R,R)-Et-Py-box)(H₂O)₂Cl]Cl ((R,R)-Et-Pybox is 2,6-bis[4′-(R)-ethoxyoxazolin-2′-yl]pyridine), was obtained and indicated by X-ray diffraction analysis. The nickel(II) complex crystallizes in the orthorhombic system, space group P2₁2₁2₁ with a = 7.7346(4) Å, b = 19.7133(13) Å, c = 25.8014(14) Å, V = 3934.1(4) ų, Z = 8, and R = 0.0526 against 7010 reflections with I > 2σ (I). A feature of interest was noted in the unit cell of the compound, where two types of molecules exist, which similarly have a distorted octahedral geometry but only slightly differ in the orientation of the coordinated atoms to the central Ni atom. These two types of molecules interact with each other by O-H…Cl hydrogen bonds, giving rise to one dimensional ribbon structure.     

Crystal and molecular structure of cis- and trans-2,4-dihydroxy-2,4-dimethylcyclohexanetrans-1-acetic acid γ-lactone

During the transformation process of limonene to tetrahydrofuran derivatives, the title compounds (±)-( 4 ) have been obtained as crystalline products and subjected to X-ray analysis. The crystals of trans-( 4 ) are orthorhombic, space group P2₁2₁2₁, with the lattice constants a = 7.0445(5) Å, b = 10.0908(4) Å, c = 14.0309(6) Å; the absolute configuration at atoms C1, C2, and C4 is R_c1, S_c2, and R_c4, respectively. The isomeric form cis-( 4 ) crystallizes in the monoclinic system, space group P2₁, with the following unit-cell parameters: a = 10.8275(4) Å, b = 8.6994(5) Å, c = 16.4722(6) Å, β = 106.515(3)°. The asymmetric part of the unit cell of cis-( 4 ) contains three independent molecules. Each of these three molecules has the identical absolute configuration at all centers of chirality: S_c1, S_c2, and R_c4. © John Wiley & Sons, Inc.     

Crystal and molecular structure and the absolute configuration of N-phenyl-N′-(1-phenylethyl)methanephosphonodiamidate

The structural investigation of the product of the reaction of methanephosphonodichloridate with R(+)-1-phenylethylamine and aniline in the presence of triethylamine [3] was performed. The obtained compound C₁₅H₁₉N₂OP ( 1 ) crystallizes in monoclinic system, space group P2₁ with a = 10.466(1) Å, b = 6.984(3) Å, c = 10.471(2) Å, β = 95.43(1)°, V = 762.0(9) ų. Z = 2, and R = 0.037. The absolute configuration at the P and C8 atoms was determined by means of X-ray crystallography as R_p and R_c8, respectively.     

The crystal structure of Mn(NO)3P(C6H5)3: The first x-ray analysis of a mononuclear metal trinitrosyl complex

The structure of Mn(NO)₃PPh₃ has been analyzed by single-crystal X-ray diffraction. It shows a tetrahedral geometry with essentially linear nitrosyl groups, and an eclipsed configuration around the MnP bond. Average distances and angles are: MnN 1.686(7) Å, MnP 2.315(2) Å, NO 1.165(10) Å, PC 1.815(4) Å, MnNO 177.2(7)°, PMnN 103.6(2)°, NMnN 114.7(4)°. Final R factor 7.3% for 2064 non-zero reflections. The structure of the five-coordinate nitrito complex Mn(NO)₂(ONO)(PEt₃)₂ is also mentioned briefly.