Nature of the Ga-Ga bonding in Na2[Arx*GaGaArx*]（Arx*=C6H3 -2,6-（C6H5）2）:Electron localization function analysis

The nature of the Ga-Ga bonding in Na2[Arx*GaGaArx*](Arx* = C6H3-2,6-(C6H5)2) has been investigated and compared with that of in H2[Arx*GaGaArx*] using electron localization function(ELF) and orbital analysis.The calculation results show that in Na2[Arx*GaGaArx*],the Ga-Ga interaction is a non-classical triple bond,the heart of Na2[Arx*GaGaArx*] is the Ga2Na2 cluster rather than a simple Ga-Ga bond,and the contribution of the sodium atoms to the short Ga-Ga bond length is considerable.As the two sodium atoms are substituted by two hydrogen atoms,the Ga-Ga bond is replaced by two 3-center,2-electron(3c-2e) Ga-H-Ga covalent bridged bonding.     

Syntheses,Crystal Structures and Herbicide Activities of Two Pyrazole Derivatives

Two novel N-acyl-3-phenylpyrazol benzophenones were designed and synthesized via cyclization and acylation with 1,3-diphenylpropane-1,3-dione and dimethylformamide dimethylacetal as the starting materials.Both of the newly synthesized compounds were characterized with IR,~1H NMR,~(13)C NMR,HRMS and single-crystal X-ray diffraction.3-Phenyl-1-o-methylbenzoyl-pyrazole-4-benzophenone(5 a) and 3-phenyl-1-p-fuorobenzoyl-pyrazole-4-benzophenone(5 b) crystallize in triclinic system,space group P1.The existence of p-π conjunction effect resulted in correlative bond length shorter than the typical bond length in both of the crystals.The presence of van der Waals forces leads to the stability of the compounds.     

Synthesis and Characterization of a Sb(Ⅲ)Complex with α-Diimine Ligand and a Csp3-Csp3 Coupling Production of the Original Ligand

A Csp3-Csp3 coupling production of the original ligand molecule [(CMeN(2,6-iPr2C6H3))2]2 (1) and an antimony ionic compound with α-diimine ligand [LH3]+[SbCl4]-(2, L = [(2,6-iPrC6H3)NC(Me)]2) were synthesized and characterized by 1H NMR, elemental analysis and single-crystal X-ray structural analysis. The crystal of compound 1 belongs to the orthorhombic system, space group Pbca with a = 21.173(4), b = 10.1639(17), c = 22.954(4) , V = 4939.8(14) 3, C56H78N4, Mr = 807.22, Z = 4, Dc = 1.085 g/cm3, μ(MoKα) = 0.062 mm-1, F(000) = 1768, S = 0.998, the final R = 0.0593 and wR = 0.1616 for 6481 observed reflections (Ⅰ > 2σ(Ⅰ)) and R = 0.0819 and wR = 0.1805 for all 28753 data. The crystal of compound 2 belongs to the triclinic system, space group P with a = 10.930(2), b = 12.553(2), c = 12.561(3) , α = 89.780(7), β = 82.861(6), γ = 68.598(4)o, V = 1590.5(5) 3, C28H43Cl4N2Sb, Mr = 671.19, Z = 2, Dc = 1.401 g/cm3, μ(MoKα) = 1.222mm-1, F(000) = 688, S = 0.989, the final R = 0.0294 and wR = 0.0616 for 7578 observed reflections (Ⅰ > 2σ(Ⅰ)) and R = 0.0366 and wR = 0.0639 for all 16515 data. Complex 1 can be rationalized as a result of Csp3-Csp3 coupling of two ligand molecules. The reaction of corres- ponding potassium salts with Sb(Ⅲ) chloride resulted in the antimony complex 2, in which the cationic moiety [LH3]+ is balanced by the presence of [SbCl4]- anion.     

Crystal Structure of Tris(2,2'-bipyridine)nickel (Ⅱ) Tetrachlorozincate

A bimetallic complex Ni[C10H8N2]3[ZnCl4] has been synthesized and its crystal structure determined at room temperature. The complex crystallizes in the trigonal system, space group R3c, with a = 13.343(2), b = 13.343(2), c =58. 932(12) A, V= 9087(3) A 3, Z = 12, NiZnC30N6CI14H24, Mr=734.30, Dc=1.611 g/cm3, μ= 1. 799 mm-1, F(000)=4464. Least-squares refinement of the structure leads to the agreement factors R1=0. 0278 and wR2=0. 0741 for the observable reflections. The complex consists of discrete tris (2, 2'-bipyridine) nickel (Ⅱ)cation, [Ni-(bipy)3]2+, and tetrachlorozincate anion, [ZnCl4]2-. Each nickel (Ⅱ)atom is six coordinated in an octahedron with six nitrogen atoms of three 2,2'-bipyridine ligands. The mean Ni(Ⅱ)-N bond length is 2. 089(2) A. The zinc(Ⅱ) atom is coordinated with four chloride atoms in tetrahedral geometry. The mean Zn (Ⅱ)- Cl bond length is 2. 264(1) A.     

Ab initio study of the transition-metal carbene cations

The geometries and bonding characteristics of the first-row transition-metal carbene cations MCH_2~ were investigated by ab initio molecular orbital theory (HF/LANL2DZ). All of MCH_2~ are coplanar. In the closed shell structures the C bonds to M with double bonds; while in the open shell structures the partial double bonds are formed, because one of the σ and π orbitals is singly occupied. It is mainly the π-type overlap between the 2p_x orbital of C and 4p_x, 3d_(xz), orbitals of M~ that forms the π orbitals. The dissociation energies of C—M bond appear in periodic trend from Sc to Cu. Most of the calculated bond dissociation energies are close to the experimental ones.     

Theoretical Study and NBO Analysis of the Decomposition Kinetics of Oxetane, 2-Methyloxetane and 2,2-Dimethyloxetane

A theoretical study of the thermal decomposition kinetics of oxetane (1), 2-methyloxetane (2), and 2,2-dimethyloxetane (3) has been carried out at the B3LYP/6-311+G**, B3PW91/6-311+G**, and MPW1PW91/6-311+G** levels of theory. The MPW1PW91/6-311+G** method was found to give a reasonable good agreement with the experimental kinetics and thermodynamic parameters. The decomposition reaction of compounds 1～3 yields formaldehyde and the corresponding substituted olefin. Based on the optimized ground state geometries using MPW1PW91/6-311+G** method, the natural bond orbital (NBO) analysis of donor-acceptor (bond-antibond) interactions revealed that the stabilization energies associated with the electronic delocalization from σC3-C4 bonding to σ*O1-C2 antibonding orbitals decrease from compounds 1 to 3. The σC3-C4→σO1-C2 resonance energies for compounds 1～3 are 2.63, 2.59 and 2.45 kcal mol-1, respectively. Further, the results showed that the energy gaps between σC3-C4 bonding and σ*O1-C2 antibonding orbitals decrease from compounds 1 to 3. Also, the decomposition process in these compounds are controlled by σ→σ* resonance energies. Moreover, the obtained order of energy barriers could be explained by the number of electron-releasing methyl groups substituted to the Csp3 atom (which is attached to oxygen atom). NBO analysis shows that the occupancies of σCsp3-O bonds decrease for compounds 1～3 as 3<2<1, and those of σCsp3-O bonds increase in the opposite order (3 > 2 > 1). This fact illustrates a comparatively easier thermal decomposition of the sCsp3-O bond in compound 3 compared to compound 2, and in compound 2 compared to compound 1. NBO results indicate that these reactions are occurring through a concerted and asynchronous four-membered cyclic transition state type of mechanism.     

DETERMINATION OF CRYSTAL STRUCTURE OF C6H5GdCl2（THF）4

<正> By X-ray (λ=0. 71069A) diffraction of single crystal,we have determined the crystal structure of C6H5GdCl2 (THF)4,C22H37Cl2O4Gd, MT=593. 2,or-thorhombic space group Ccm2;with lattice parameters a=12. 776(6),b=12. 954(6), c=15. 802(3)A ;V=2615. 4(1. 8)A3;Z=4,Dc=2. 43gcm-3,μ=29. 3cm-1,F(000) = 1120. The structure was solved by heavy-atom method and Fourier techniques and refined by least-squares to a final R=0. 051 ,Rw = 0. 049 for 839 reflections with I≥1. 5σ (I). The results revealed that the bond length of Gd-C is 2. 437(22) A ,the average bond lengths of Gd-Cl 2. 678(6) A ,Gd-O 2. 499(12) A, C-C from phenyl group 1. 376(40)A. This crystal structure is the first organolanthanide complex with only one Ln-C bond in the molecule.     

Molecular Spectra and Dissociation Dynamics of Oxalyl Chloride: Effect of External Electrical Fields

Oxalyl chloride is a highly toxic and caustic substance, which widely exists in human production and life as a kind of volatile organic compound. Based on the density functional theory B3 LYP at 6-311++G(d, p) level, the influences of external electric field on the bond length, bond energy, dipole moment and dissociation mechanism are optimized. The results indicate that the C_1–Cl_3 bond length increases while the C_4–Cl_6 bond decreases. At the same time, the carbon-carbon bond length gradually increases with the increase of electric field. The total energy decreases while the dipole moment gradually increases with the increase of electric field. In the infrared spectra, the vibration frequency of the carbon-chlorine(C_4–Cl_6) bond decreases while the vibration frequency of the carbon-oxygen bond increases. In the ultraviolet-visible spectra, the wavelength of the strongest absorption peak increases as the external electric field increases and shows an observable red shift phenomenon. Additionally, single point energies of oxalyl chloride along the carbon-carbon bond are scanned with the equation-of-motion coupled cluster method restricted to single and double excitations(EOM-CCSD) method and the potential energy curves under different external electric fields are obtained. The dissociation barrier in potential energy curve decreases because of the breakage of carbon-carbon bond with the increase of external electric field. These results provide reference for further researches on the properties of oxalyl chloride and offer a theoretical basis for the study of oxalyl chloride degradation.     

Density Functional Study on the Reaction Mechanism for the Reaction of Ni^＋ with Ethane

The mechanism of the reaction of Ni^ (^2D) with ethane in the gas-phase was studied by using density functional theory.Both the B3LYP and BLYP functionals with standard all-electron basis sets are used to give the detailed information of the potential energy surface (PES) of [Ni,C2,H6]^ . The mechanisms forming the products CH4 and H2 in the reaction of Ni^ with ethane are proposed.The reductive eliminations of CH4 and H2 are typical addition-elimination reactions.Each of the two reactions consists of two elementary steps:C-C or C-H bond activations to form inserted species followed by isomerizations to from product-like intermediate.The rate determining steps for the elimination reactions of forming CH4 and H2 are the isomerization of the inserted species rather than C-C or C-H bond activations .The elimination reaction of forming H2 was found to be thermodynamically favored compared to that of CH4.     

Cleavage of the Fe—Fe Bond of （Me2SiSiMe2） [η^5－C5H4Fe（CO）2]2 with Na／Hg and Molecular Structure of the Ring－Opened Complex

The reaction of the rifle cyclic complex (1) with sodium amalgam in THF resulted in the expected cleavage of the Fe-Fe bond to afford his-sodium salt ( Me2SiSiMe2 ) [η^5-C5H4Fe(CO)2]2 (4). The latter was not isolated and was used directly to react with MeI, PhCH2Cl, CH3C(O)Cl, PhC(O)Cl,Cy3SnCl (Cy= cyclohexyl) or Ph3SnCl to afford corresponding ring-opened derivatives (Me2SiSiMe2) [η^5-C5H4Fe(CO)2]2 [5, R=Me; 6, R=PhCH2; 7, R=CH3C(O); 8, R=PhC(O); 9, R = Cy3Sn or 10, R = Ph3Sn ]. The crystal and molecular structures of 10 were determined by X-ray diffraction analysis. The molecule took the desired ant/ conformation around the Si-Si bond. The length of the Si--Si bond is 0.2343(3)nm, which is essentially identical to that in the cyclic structure of 1[0.2346(4) tun]. This result unambiguously demonstrates that the Si--Si bond in the cyclic structure of 1 is not subject to obvious strain.     

Structures and properties of π Br‐bond in complexes C2H4−nFn?BrF (n = 0–2)

Using the counterpoise‐corrected potential energy surface method, the stationary structures of the π Br‐bond complexes C₂H_4‐nF_n? BrF (n = 0–2) with all real frequencies have been obtained at MP2/aug‐cc‐pVDZ level. The order of the π Br‐bond length is 2.625 Å (C₂H₄? BrF) < 2.714 Å (C₂H₃F? BrF) < 2.751 Å (g‐C₂H₂F₂? BrF) < 2.771 Å (trans‐C₂H₂F₂? BrF) < 2.778 Å (cis‐C₂H₂F₂? BrF). The interaction energies (E_int) are, respectively,‐5.9 (C₂H₄? BrF),‐4.4 (C₂H₃F? BrF),‐3.7 (g‐C₂H₂F₂? BrF),‐3.1 (cis‐C₂H₂F₂? BrF),‐2.8 kcal/mol (trans‐C₂H₂F₂? BrF), at the CCSD (T)/aug‐cc‐pVDZ level, which include larger electron correlation contributions (E_corre). The order of E_corre is‐3.40 (C₂H₄? BrF),‐3.60 (C₂H₃F? BrF),‐3.85 (g‐C₂H₂F₂? BrF),‐3.86 (cis‐C₂H₂F₂? BrF),‐3.88 kcal/mol (trans‐C₂H₂F₂? BrF). The earlier results show above that the F substituent effect elongates the π Br‐bond, reduces the E_int, and increases the E_corre contribution of the interaction energy. Interestingly, the interaction energy of the cis‐C₂H₂F₂? BrF structure with longer interaction distance is larger than that of the corresponding trans‐C₂H₂F₂? BrF structure with shorter interaction distance. This reason comes from a special secondary interaction between lone pairs of Br atom with positive charge and some atoms (H, C) with positive charges of C₂H₂F₂ in the cis‐C₂H₂F₂? BrF structure. Comparing with corresponding C₂H_4‐nF_n? ClF and C₂H_4‐nF_n? HF, the C₂H_4‐nF_n? BrF system has the larger E_int in which main contribution comes from the larger E_corre, representing the larger dispersion interaction. The larger E_corre contribution of the E_int of π Br‐bond can be used to understand that the π Br‐bond is shorter and stronger than corresponding π Cl‐bond. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008     

Quenching rate constants for the removal of SO2(3B1) by various fluorinated olefins

A competitive technique employing the SO₂(³B₁) photosensitized isomerization of cis-C₂F₂H₂ to trans-C₂F₂H₂ in the presence of selected fluorinated olefins has been used at 3712 Å and 22°C to determine the quenching rate constants of the reaction \documentclass{article}\pagestyle{empty}\begin{document}${\rm SO}_{\rm 2} ({}^3B_1){\rm M}\mathop \to \limits^{k_{_4}}$\end{document} removal. With P_So2 = 25.4 torr and P_cis-C₂F₂H₂ = 0.239 torr Stern–Volmer plots for M = C₂H₄, C₂H₂F, 1,1-C₂F₂H₂, C₂F₄, and C₃F₆ yielded k₄ (units of 10¹⁰ l./mole · sec) values of 5.29 ± 0.16, 4.21 ± 0.53, 1.92 ± 0.23, 0.575 ± 0.060, and 0.0335 ± 0.0027, respectively. The results were consistent with the ability of an olefin to quench SO₂(³B₁) being inversely proportional to the polarizability of the olefin's π bond and the effect can be clearly noted as each H atom in C₂H₄ is individually replaced by an F atom.     

The trans influence in mer‐tri­chloro­nitridobis­(tri­phenyl­arsine)­ruthenium(VI)

The title compound, mer‐[RuCl₃N(C₁₈H₁₅As)₂], is the first structurally characterized example of a nitride complex in which ruthenium is six‐coordinated to monodentate ligands only. The Ru[triple‐bond]N bond length [1.6161 (15) Å] is relatively long, and the trans influence of the nitride ligand is reflected by the difference between the Ru—Cl_trans and Ru—Cl_cis bond lengths [0.1234 (4) Å]. The N—Ru—Cl_trans axis is sited on a twofold axis.     

Crystal and molecular structure of (μ-p-CH3C6H4C2S) (μ-n-C3H7S)Fe2(CO)6Co2(CO)6

The crystal and molecular structure of the complex containing cobalt-carbon and iron-sulfur cluster cores, (μ-p-CH₃C₆H₄C₂S) (μ-n-C₃H₇S)Fe₂(CO)₆Co₂(CO)₆, has been determined by X-ray diffraction method. The crystals are triclinic, space group P&1bar;, with a — 9.139(2), b=9.610(1), c-17.183(2) Å, α = 84.36(1), β-89.45(1), γ=88.15(1)°, V-1501.0 ų; Z=2, D_c=1.74 g/cm³. R=0.072, Rw=0.081. The results of the structure determination show a cobalt-carbon cluster core formed through the reaction of (μ-p-CH₃C₆H₄C₂S)(μ-n-C₃H₇S)Fe₂(CO)₆ with Co₂(CO)₈. In the cobalt-carbon cluster core, the bond length of the original C≡C lengthened to 1.324 Å which is close to the typical value of carbon-carbon double bond. The groups connecting the carbons of the cluster core are in cis position and lie on the opposite side of cobalt atoms. In this complex, the conformation of —SC₃H₇ is e-type, while that of —SC₂C₆H₄CH₃ is a-type.     

The photolysis of SO2 at 3130 Å in the presence of cis- and trans-2-pentene

The photolysis of SO₂ at 3130 Å, FWHM = 165 Å, and 22°C has been investigated in the presence of cis- and trans-2-pentene. Quantum yields for the SO₂ photosensitized isomerization of one isomer to the other have been made for a variation in the [SO₂]/[C₅H₁₀] ratio of 3.41–366 for cis-2-C₅H₁₀ and of 1.28–367 for trans-2-C₅H₁₀. A kinetic analysis of each of these systems permitted new estimates to be made for the SO₂ collisionally induced intersystem crossing ratio at 3130 Å from SO₂(¹B₁) to SO₂(³B₁). The estimates of k_1a/(k_1a + k_1b) obtained are 0.12 ± 0.01 and 0.12 ± 0.02 (two different kinetic analyses in the cis-2-C₅H₁₀ study) and 0.20 ± 0.05 and 0.20 ± 0.04 (two different kinetic analyses in the trans-2-C₅H₁₀ study). Collisionally induced intersystem crossing ratios of k_2a/(k_2a + k_2b) = 0.51 ± 0.10 and k_3a/(k_3a + k_3b) = 0.62 ± 0.12 were obtained for cis- and trans-2-pentene, respectively. Quenching rate constants at 22°C for removal of SO₂(³B₁) molecules by cis- and trans-2-C₅H₁₀ were estimated as (1.00 ± 0.29) × 10¹¹ l./mole·sec and (0.857 ± 0.160) × 10¹¹ l./mole/sec, respectively. Prolonged irradiations, extrapolated to infinite irradiation times, for mixtures initially containing SO₂ and pure isomer, either the cis or trans, yielded a photostationary composition of [trans-2-pentene]/[cis-2-pentene] = 2.1 ± 0.1.     

Cyano­cobalt(III) complexes of penta‐ and tetra­dentate‐coordinated macrocyclic hexa­amines

The pendent‐arm macrocyclic hexa­amine trans‐6,13‐dimethyl‐1,4,8,11‐tetra­aza­cyclo­tetra­decane‐6,13‐diamine (L) may coordinate in tetra‐, penta‐ or hexa­dentate modes, depending on the metal ion and the synthetic procedure. We report here the crystal structures of two pseudo‐octa­hedral cobalt(III) complexes of L, namely sodium trans‐cyano­(trans‐6,13‐dimethyl‐1,4,8,11‐tetra­aza­cyclo­tetra­decane‐6,13‐diamine)cobalt(III) triperchlorate, Na[Co(CN)(C₁₃H₃₀N₆)](ClO₄)₃ or Na{trans‐[CoL(CN)]}(ClO₄)₃, (I), where L is coordinated as a penta­dentate ligand, and trans‐dicyano­(trans‐6,13‐dimethyl‐1,4,8,11‐tetra­aza­cyclo­tetra­decane‐6,13‐diamine)cobalt(III) trans‐dicyano­(trans‐6,13‐dimethyl‐1,4,8,11‐tetra­aza­cyclo­tetra­decane‐6,13‐diaminium)cobalt(III) tetra­perchlorate tetra­hydrate, [Co(CN)₂(C₁₄H₃₂N₆)][Co(CN)₂(C₁₄H₃₀N₆)](ClO₄)₄·4H₂O or trans‐[CoL(CN)₂]trans‐[Co(H₂L)(CN)₂](ClO₄)₄·4H₂O, (II), where the ligand binds in a tetra­dentate mode, with the remaining coordination sites being filled by C‐­bound cyano ligands. In (I), the secondary amine Co—N bond lengths lie within the range 1.944 (3)–1.969 (3) Å, while the trans influence of the cyano ligand lengthens the Co—N bond length of the coordinated primary amine [Co—N = 1.986 (3) Å]. The Co—CN bond length is 1.899 (3) Å. The complex cations in (II) are each located on centres of symmetry. The Co—N bond lengths in both cations are somewhat longer than in (I) and span a narrow range [1.972 (3)–1.982 (3) Å]. The two independent Co—CN bond lengths are similar [1.918 (4) and 1.926 (4) Å] but significantly longer than in the structure of (I), again a consequence of the trans influence of each cyano ligand.     

The molecular structure of norbornene as determined by electron diffraction and microwave spectroscopy

The molecular structure of norbornene has been investigated in the gas phase by combining electron diffraction data with microwave spectroscopic rotational constants. The interatomic distances (r_g) and bond angles were obtained by applying a least squares program to the refined experimental molecular diffraction intensities. The CC bond length was found to be 1.336 ± 0.002 Å while the

) bond length was 1. 529 ± 0.007 Å. Other bond lengths and angles included (IUPAC numbering system was used for norbornene): C₁-C₆ = 1.550 ± 0.020 Å, C₁-C₇ = 1.566± 0.005 Å, C₅-C₆ = 1.556 ± 0.005 Å, C-H_ave. = 1.103 ± 0.003 Å, ∠C₁C₂C₄ = 95.3°. The dihedral angle between planes C₁C₂C₃C₄ and C₁C₆C₅C₄ is 110.8 ± 1.5° while that between C₁C₂C₃C₄ and C₁C₇C₄ is 122.3°. The moments of inertia calculated from ED structure are in good agreement with microwave spectroscopic values.     

The photolysis of SO2 at 3080 Å in the presence of cis- and trans-1,2-difluoroethylene

The photolysis of SO₂ at 3080 Å, FWHM = 150 Å, and 22°C has been investigated in the presence of cis- and trans-C₂F₂H₂. Quantum yield measurements for the photosensitized isomerization of cis-C₂F₂H₂ to trans-C₂F₂H₂ have been made for a variation in the [SO₂]/[cis-C₂F₂H₂] ratio from 0.992 to 253. The results fit a mechanism which is consistent with the SO₂(³B₁) state being the reactive excited state of sulfur dioxide. A mechanism employing only the SO₂(¹B₁) and SO₂(³B₁) excited states is quite satisfactory to rationalize the data. A value for the SO₂ collisionally induced intersystem crossing efficiency from SO₂(¹B₁) to SO₂(³B₁) of 0.35 ± 0.14 was estimated while the cis-C₂F₂H₂ efficiency was found to be 0.030 ± 0.012. The rate constant at 22°C for the removal of SO₂(³B₁) molecules by cis-C₂F₂H₂ was found to be (1.43 ± 0.13) × 10¹⁰1./mole · sec. A photostationary composition, [cis]/[trans] = 1.0 ± 0.1, was found from prolonged irradiations of SO₂ in the presence of the cis and trans isomers.     

Dimeric uranium complexes with bridging phospholyl ligands. Crystal structure of [{U(η5-C4Me4P)(μ-η5-C4Me4P)(BH4)}2]

In the symmetrical crystal structure of [{U(η⁵-C₄Me₄P)(μ-η⁵,η¹-C₄Me₄P)(BH₄)}₂], the U-P bond distances for the terminal and bridging η⁵-phospholyl ligands are 2.945(3) and 2.995(3) Å respectively, and the U-P (η¹-phospholyl) bond length is equal to 2.996(3) Å; the tridentate borohydride ligands are cis to the (UP)₂ ring. The cis and trans isomers of [{U(Cp¹)(μ-η⁵,η¹C₄ Me₄P)(BH₄)}₂] (Cp¹ = η⁵-C₅Me₅) are in equilibrium in toluene.     

(Nitro‐κN)[2‐(phenyldiazenyl‐κN2)pyridine‐κN](2,2′:6′,2′′‐terpyridine‐κ3N)ruthenium(II) tetrafluoroborate

The Ru—N bond distances in the title complex, [Ru(NO₂)(C₁₁H₉N₃)(C₁₅H₁₁N₃)]BF₄ or [Ru(NO₂)(tpy)(azpy)]BF₄, [tpy is 2,2′:6′,2′′‐ter­pyridine and azpy is 2‐(phenyl­azo)­pyridine], are Ru—N_py 2.063 (4), Ru—N_azo 2.036 (4), Ru—N_nitro 2.066 (3) Å, and Ru—N_tpy 2.082 (4), 1.982 (3) and 2.074 (4) Å. The azo N atom is trans to the nitro group. The azo N=N bond length is 1.265 (5) Å, which is the shortest found in such complexes to date. This indicates a multiple bond between Ru and the N atom of the nitro group, and π‐­backbonding [dπ(Ru) π*(azo)] is decreased.