Anionic Fischer-type carbene complexes as bidentate (N,O) ligands

New polynuclear complexes, (L1)3M2 [M2 = Cr(III) (4a,4b), Fe(III) (5), Co(III) (8)], (L1)2M2(L2)2 [M2 = Co(II) (7), Ni(II) (9)], (L1)2M2(O)L2 [M2 = V(IV) (6)] and L1M2Cp2 [M2 = Ti(III) (10)] with L1 = (CO)5M1=C[C=NC(CH3)=CHS](O-)(M1 = Cr or W) and L2 = 4-methylthiazole or THF, are described. The molecular structures of these complexes determined by X-ray diffraction show that the Fischer-type carbene complexes act as bidentate ligands towards the second metal centre, coordinating through C(carbene)-attached O-atoms and imine N-atoms of the thiazolyl groups to form five-membered chelates with the oxygen atoms in the mer configuration. Isostructural complexes have similar characteristic band patterns in their far-IR spectra. Cyclic voltammetry of selected complexes reveals the oxidation of the carbene complex ligand between 1.01 and 1.29 V. Oxidation of the central metal (M2) takes place at 0.56 and 0.86 V for 7 and 9, respectively. Three stepwise reductions of Cr(III) to Cr(0) occur for 4a and 4b in the region -0.51 to -1.58 V. These new ligand types and other variants thereof should find application in ligand design with the first metal -- and other ligands attached thereto -- in the carbene complex ligand, playing an important role.     

Synthesis,characterization, DNA binding studies and in vitro cytotoxicity of platinum(II)-dihalogenido complexes containing bidentate chelating N-donor ligands

Platinum(II) complexes, [Pt(L_x)X₂] (1–6), where X = Br or I and L_x = 2,2′-bipyridine or 1,10-phenanthroline derivatives (5,5′-dimethyl-2,2′-bipyridine (5-Mebpy), 4,4′-dimethyl-2,2′-bipyridine (4-Mebpy), and 5-amino-1,10-phenanthroline (5-NH₂phen)) were prepared. The complexes were characterized by the elemental analysis, mass spectrometry, infrared, and multinuclear (¹H, ¹³C and ¹⁹⁵Pt) 1-D and 2-D NMR spectroscopies, and by single-crystal X-ray analysis of [Pt(4-Mebpy)I₂] (4). All the platinum(II) complexes (1–6) were evaluated for in vitro cytotoxicity against human cancer cell lines A2780 and A2780R, and against non-malignant MRC5 cell line. All the complexes were nontoxic up to the 50 μM concentration, although they were found to readily bind to calf-thymus DNA (CT-DNA), as determined by spectrophotometric titration (K_b ≈ 10⁷ M^?1) and ethidium bromide displacement assay.     

Synthesis and characterization of copper(II) complexes incorporating pyrazolyl-derived N,S-donor bidentate ligands

The novel bidentate N,S-donor anionic ligands [PhNCSIndz]^?, [PhNCSImz]^?, [PhNCSPz^Me3]^?, and [EtNCSPz]^?, where Indz?=?indazole, Imz?=?imidazole, Pz^Me3?=?3,4,5-trimethylpyrazole, and Pz?=?pyrazole, were synthesized and used to prepare Cu(II) complexes of general formula [Cu(N^S)₂]. The ligands were synthesized via direct addition of phenylisothiocyanate or ethylisothiocyanate into THF suspensions of the corresponding sodium-pyrazolate salts. All of the synthesized compounds, including the ligands and the complexes, were characterized by physico-chemical and spectroscopic methods, and crystal structures of [Cu(EtNCSPz)₂] and [Cu(PhNCSPz^Me2)₂] were determined by X-ray diffraction analysis, showing a trans-square planar geometry for [Cu(EtNCSPz)₂] and a distorted tetrahedral geometry for [Cu(PhNCSPz^Me2)₂].     

Polypyridyl ruthenium(II) complexes with tetrazolate-based chelating ligands. Synthesis, reactivity, and electrochemical and photophysical properties

In this contribution, we report the synthesis, the chemical and photophysical characterization, and the study of the reactivity toward electrophiles of two mononuclear complexes of the type [Ru(bpy)2L]+ (bpy is 2,2'-bipyridyl), in which L is represented by the deprotonated form of 2-(1,H-tetrazol-5-yl)pyridine (L1) or 2-(1,H-tetrazol-5-yl)pyrazine (L2). The 1H and 13C NMR experiments that were performed on complexes RuL1 and RuL2 allowed us to establish that the tetrazolate moiety is bonded to the metal center via the N-1 nitrogen, while the coplanar arrangement adopted by the coordinated ligand upon coordination and the consequent interannular conjugation effect accounts for the unexpectedly low field resonance of the tetrazole carbon. The 13C NMR spectroscopy is also of fundamental importance to determine the chemo- and regioselectivity of the addition of a methyl group to RuL1 and RuL2, which takes place at the N-3 nitrogen of the five-membered ring. All these features were confirmed by the X-ray diffraction structures of RuL1 and of the methylated compounds RuL1Me and RuL2Me. Relative to these latter complexes, the presence of a methyl moiety does not cause any distortion from coplanarity of the coordinated tetrazolates. The redox properties of the complexes were investigated by cyclic voltammetry and indicated a quite different behavior between the pyrazinyl-tetrazolate and the pyridyl-tetrazolate complexes as the consequence of the higher electron-withdrawing character of the pyrazine ring. The study of the photophysical properties of the complexes also shows a significant diversity between the luminescent RuL1 and the rather poorly emissive RuL2. Interestingly, the methylated compounds RuL1Me and RuL2Me display radiative excited-state decays with longer lifetimes than their precursors; this feature indicates that methylation is a useful reaction for the tuning of the light emission performances of similar tetrazolate complexes. The synthesis and the characterization of a novel dinuclear complex of type [(bpy)2Ru-L3-Ru(bpy)2]2+, Ru(L3)Ru, where L3 is the bis-anion derived from bis-2,3-(1,H-tetrazol-5-yl)pyrazine, is also reported.     

Substituted benzeneseleninic acids as bidentate ligands. Synthesis and spectroscopic studies of manganese(II) and iron(II) complexes

The para- and meta-substituted seleninato anion, XC₆H₄SeO⁻₂, forms complexes with manganese(II) and iron(II) of the type [M(XC₆H₄SeO₂)₂(H₂O)₂], which have been shown to contain the bidentate ligand in seleninato-_O, O′ derivatives, the water molecules being coordinated to the metals. From the electronic absorption spectra and from the magnetic susceptibility data we have proposed for all the complexes a distorted octahedral D_4h symmetry. The structure of the anhydrous para- and meta-substituted benzeneseleninato complexes of manganese(II) and iron(II) have been investigated by means of electrical conductance measurements, spectral (electronic and i.r.) studies and magnetic susceptibility measurements. The anhydrous complexes are always of the seleninato-O, O′ type with the ligands tetrahedrally coordinated to the central atom. The wavelengths of the principal absorption peaks have been accounted for quantitatively in terms of the crystal field theory for manganese(II) derivatives. The nephelauxetic parameters are all indicative of an appreciable metal-ligand covalency.     

Thermodynamic and kinetic studies on novel dinuclear platinum(II) complexes containing bidentate N,N-donor ligands

A series of novel dinuclear platinum(II) complexes were synthesized with bidentate nitrogen donor ligands. The two platinum centers are connected by an aliphatic chain of variable length. The selected chelating ligand system should stabilize the complex toward decomposition. The pK(a) values and reactivity of four synthesized complexes, viz. [Pt(2)(N(1),N(4)-bis(2-pyridylmethyl)-1,4-butanediamine)(OH(2))(4)](4+) (4NNpy), [Pt(2)(N(1),N(6)-bis(2-pyridylmethyl)-1,6-hexanediamine)(OH(2))(4)](4+) (6NNpy), [Pt(2)(N(1),N(8)-bis(2-pyridylmethyl)-1,8-octanediamine)(OH(2))(4)](4+) (8NNpy), and [Pt(2)(N(1),N(10)-bis(2-pyridylmethyl)-1,10-decanediamine)(OH(2))(4)](4+) (10NNpy), were investigated. This system is of special interest because only little is known about the substitution behavior of dinuclear platinum complexes that contain a bidentate chelate that forms part of the aliphatic bridging ligand. Spectrophotometric acid-base titrations were performed to determine the pK(a) values of the coordinated water ligands. The substitution of coordinated water by thiourea was studied under pseudofirst-order conditions as a function of nucleophile concentration, temperature, and pressure, using stopped-flow techniques and UV-vis spectroscopy. The results for the dinuclear complexes were compared to those for the corresponding mononuclear reference complex [Pt(aminomethylpyridine)(OH(2))(2)](2+) (monoNNpy), by which the effect of increasing the aliphatic chain length on the bridged complexes could be investigated. The results indicated that there is a clear interaction between the two platinum centers, which becomes weaker as the chain length between the metal centers increases. In addition, quantum chemical calculations were performed to support the interpretation and discussion of the experimental data.     

Synthesis and analytical properties of a chelating resin functionalised with bis-(N,N'-salicylidene)1,3-propanediamine ligands

A polystyrenedivinylbenzene-based macroreticular resin was functionalised with bis-(N,N'-salicylidene)1,3-propanediamine ligands and its analytical properties have been investigated. The pH dependence of metal resin chelation has been determined for Cu(II), Ni(II), Co(II), Zn(II), Fe(II), Mn(II), Pb(II), Cd(II) and Cr(III). Trace amounts of these metal ions were quantitatively retained on the resin at neutral pH and easily recovered by elution with 1 N hydrochloric acid. The resin exhibits good chemical stability and fast equilibration with the metal ion making it useful for rapid concentration of trace amounts of metal ions on the resin columns.     

Synthesis, characterization and reactivity of palladium(II) compounds containing terdentate [Csp, N, S] or [Csp, N, S] ligands

The study of the reactivity of R---CH=N---(C₆H₄-2-SMe) with R=C₆H₅ or 2,4,6-Me₃-C₆H₂ with palladium(II) salts is reported. These studies have allowed us to prepare and characterize the coordination complexes: cis-[Pd{R---CH=N---(C₆H₄-2-SMe)}Cl₂] {R=C₆H₅ or 2,4,6-Me₃-C₆H₂} and the cyclopalladated compounds [Pd{C₆H₄---CH=N---(C₆H₄-2-SMe)}Cl] and [Pd{(2-CH₂-4,6-Me₂-C₆H₂)---CH=N---(C₆H₄-2-SMe)}Cl]. The X-ray crystal structures of the latter complexes reveal that the thioimines act as a [Csp², phenyl,N,S]⁻ and as a [Csp³, N,S]⁻ terdentate group, respectively. The study of the reactions of the cyclopalladated compounds with PPh₃ is also reported.     

Synthesis, characterization, electro chemistry, catalytic and biological activities of ruthenium(III) complexes with bidentate N, O/S donor ligands

New hexa-coordinated ruthenium(III) complexes of the type [RuX(2)(EPh(3))(2)(L)] (E=P or As; X=Cl or Br; L=monobasic bidentate Schiff base derived from the condensation of benzhydrazide with furfuraldehyde, 2-acetylfuran and 2-acetylthiophene) have been synthesized from the equimolar amounts of [RuX(3)(EPh(3))(3)] or [RuBr(3)(PPh(3))(2)(MeOH)] and Schiff bases in benzene. The new complexes have been characterized by analytical, spectral (IR, electronic and EPR), magnetic moment, and cyclic voltammetry. An octahedral structure has been tentatively proposed. All the complexes have exhibited catalytic activity for the oxidation of benzyl alcohol, cyclohexanol and cinnamylalcohol in the presence of N-methylmorpholine-N-oxide as co-oxidant. All the new complexes were found to be active against the bacteria such as E. coli, Pseudomonas, Salmonella typhi and Staphylococcus aureus. The activity was compared with standard Streptomycin.     

Oxorhenium(V) complexes containing bidentate N,O-donor ligands of the pyridyl type

The reaction of equimolar quantities of trans-[ReOCl₃(PPh₃)₂] and 8-hydroxyquinoline (Hhqn) in benzene led to the isolation of the six-coordinate complex [ReOCl₂(hqn)(PPh₃)] (1). With 2-pyridine-ethanol (Hhep) the compound [ReOCl₂(hep)(PPh₃)] (2) was obtained. Both hqn and hep ligands act as monoanionic bidentate N,O-donor chelates. Although the two complexes are very similar, there are some significant differences in certain bond distances and angles in them. Both complexes contain the nearly linear trans O=Re–O axis, with this angle equal to 160.9(2)° and 167.8(1)° in 1 and 2, respectively.     

Synthesis, structures and electrochemical properties of ruthenium (II) complexes bearing bidentate 1,8-naphthyridine and terpyridine analogous (N,N,C)-tridentate ligands

1,8-Naphthyridine (napy) and terpyridine-analogous (N,N,C) tridentate ligands coordinated ruthenium (II) complexes, [RuL(napy-κ²N,N′) (dmso)](PF₆)₂ (1: L=L¹=N″-methyl-4′-methylthio-2,2′:6′,4″-terpyridinium, 2: L = L² = N″-methyl-4′-methylthio-2,2′:6′,3″-terpyridinium) were prepared and their chemical and electrochemical properties were characterized. The structure of complex 1 was determined by X-ray crystallographic study, showing that it has a distorted octahedral coordination style. The cyclic voltammogram of 1 in DMF exhibited two reversible ligand-localized redox couples. On the other hand, the CV of 2 shows two irreversible cathodic peaks, due to the Ru-C bond of 2 containing the carbenic character. The IR spectra of 1 in CO₂-saturated CH₃CN showed the formation of Ru-(η¹-CO₂) and Ru-CO complexes under the controlled potential electrolysis of the solution at −1.44 V (vs. Fc/Fc⁺). The electrochemical reduction of CO₂ catalyzed by 1 at −1.54 V (vs. Fc/Fc⁺) in DMF-0.1 M Me₄NBF₄ produced CO with a small amount of HCO₂H.     

Synthesis, structures and oxygen atom transfer catalysis of oxo-bridged molybdenum(V) complexes with heterocyclic bidentate ligands (N,X) X = S, Se

The dinuclear μ-oxomolybdenum(V) complexes [Mo₂O₃(PyS)₄] (1), [Mo₂O₃(PySe)₄] (2) and [Mo₂O₃(4-CF₃-PymS)₄] (3) were obtained by similar reactions of the [MoO₂Cl₂(DME)] precursor with the corresponding heterocyclic bidentate (N,X) ligands, X = S, Se, where PyS, PySe and 4-CF₃-PymS are the anions of pyridine-2-thione, pyridine-2-selenolato and 4-trifluoromethyl-2-pyrimidinthiol, respectively. All compounds were characterized by elemental analysis, IR, NMR, EI-MS spectroscopy and X-ray diffraction. The crystal structures of 1–3 all include the common [Mo₂O₃]⁴⁺ core. Compounds 1 and 2 are isostructural. The catalytic oxo-transfer properties of the molybdenum(V) compounds 1 and 2 were studied by the use of PPh₃ in DMSO with a considerably higher catalytic activity for the thionato containing complex 1 than for its selenolato containing analogue 2.     

Dendritic polyallyl and polyferrocenyl bipyridine ligands: Synthesis, MALDI-TOF characterization and ruthenium(II) complexation studies

A series of 6- and 18-armed dendritic polyallyl- and polyferrocenyl-containing bipyridine ligands were synthesized through the coupling reaction of 4,4′-bis(bromomethyl)-2,2′-bipyridine with AB₃ and AB₉ dendrons. All these bipyridine ligands were successfully characterized using standard physico-chemical techniques as well as MALDI-TOF mass spectrometric analysis. The complexation studies of these ligands toward RuCl₂(bpy)₂ indicated that, in contrast to the bulky 18-ferrocenyl bipyridine ligand 7, the 6-allyl 4 and the 18-allyl 5 bipyridine ligands react with Ru(bpy)₂Cl₂ to give the corresponding ruthenium(II) complexes 9 and 10. In the case of ligand 7, the steric bulk of the two nonaferrocenyl wedges at the 4,4′-position of the bipyridine moiety prevents the conversion of the transoid structure of the ligand to the cisiod structure needed for chelation to the metal. Thus, the 18-ferrocenyl ruthenium(II) dendrimer was not obtained. Metallodendrimers 9 and 10 have been characterized by a combination of analytical methods, especially MALDI-TOF mass spectrometric techniques. The hydrogenation of the 6-allyl ruthenium(II) dendrimer 9 in the presence of Pd/C catalyst gave the expected n-propyl complex 11. This reaction constitutes a new way for the direct synthesis of alkyl bipyridine metallodendrimers. The coordination of the alkene dendritic bipyridine ligand to the metal before the catalytic hydrogenation is absolutely necessary, because of their poisoning effect for the catalyst.     

Synthesis,spectroscopic evaluation,molecular modelling,thermal study and biological evaluation of manganese(II) complexes derived from bidentate N,O and N,S donor Schiff base ligands

Manganese(II) complexes having the general composition Mn(L)₂X₂ (where L = 3‐bromoacetophenone semicarbazone, 3‐bromoacetophenone thiosemicarbazone, 1‐tetralone semicarbazone, 1‐tetralone thiosemicarbazone, flavanone semicarbazone or flavanone thiosemicarbazone and X = Cl^? or ½SO₄^2?) were synthesized. All the complexes were characterized using elemental analyses, molar conductance and magnetic moment measurements, and mass, ¹H NMR, infrared, electron paramagnetic resonance and electronic spectral studies. The molar conductance of the complexes in dimethylsulfoxide lies in the range 10–20 Ω^?1 cm² mol^?1 indicating their non‐electrolytic nature. All the complexes show magnetic moments corresponding to five unpaired electrons. The possible geometries of the complexes were assigned on the basis of electron paramagnetic resonance, electronic and infrared spectral studies. Some of the synthesized ligands and their complexes were screened for their antifungal activities against fungi Macrophomina phaseolina, Botrytis cinerea and Phoma glomerata using the food poison technique and their antibacterial activities against Xanthomonas campestris pv. campestris and Ralstonia solanacearum using the paper disc diffusion method. They showed appreciable activities.     

Synthesis,characterization, and reactivity studies in ethylene polymerization of cyclometalated palladium(II) complexes containing terdentate ligands with N,C,N-donors

The reaction of [Na₂PdCl₄] with 3,5-bis(2-pyridoxy)toluene (L_pyH) in acetic acid yields the cyclometalated complex [PdCl(L_py-N, C, N)] (1). Complex 1 can be further converted into neutral species by metathesis reaction exchange of chloride by either iodide or thiocyanate to yield [PdX(L_py-N, C, N)] (X = I (2), SCN (3)). The chloride can be replaced by neutral ligands like pyridine or acetonitrile in the presence of silver tetrafluoroborate to give the corresponding cationic compounds [PdL(L_py-N, C, N)]BF₄ (L = Py (4), MeCN (5)). In contrast, the reaction of [Na₂PdCl₄] with 3,5-bis(3, 5-dimethylpyrazol-1-ylmethyl)toluene (L_pzH) under analogous conditions yields the neutral complex [PdCl₂(L_pzH-N, N)](6) with the ligand bidentate N,N-donor. The cyclometalated palladium complex [PdCl(L_pz-N, C, N)] (7) was prepared by the reaction of Pd(OAc)₂ with L_pzH in acetic acid followed by a metathetic reaction with lithium chloride in acetone/water. Complexes 1, 6, and 7 in the presence of methylaluminoxane (MAO) lead to an active catalyst for the polymerization of ethylene.     

3,6-Di-tert-butyl-o-benzosemiquinone complexes of copper(1) with bidentate bis(diphenylphosphine) ligands. Synthesis, structures, and properties

New mononuclear 3,6-di-tert-butyl-o-benzosemiquinone complexes of copper(1) with bis(diphenylphosphine) ligands were synthesized: (DBSQ)Cu(dppe) (1) (DBSQ=3,6-di-tert-butyl-o-benzosemiquinone and dppe=1,2-bis(diphenylphosphino)ethane), (DBSQ)Cu(dppp) (2) (dppp=1,3-bis(diphenylphosphino)propane), (DBSQ)Cu(dppn) (3) (dppn=2,2′-bis(diphenylphosphino)-1,1′-binaphthyl), and (DBSQ)Cu(dppfc) (4) (dppfc=1,1′-bis(diphenylphosphino)ferrocene). The compositions and structures of complexes1–4 were characterized by elemental analysis and electronic absorption, IR, and ESR spectroscopy. The molecular structures of complexes3 and4 were established by X-ray diffraction analysis. The reactions of elimination and replacement of neutral ligands in the coordination sphere of the complexes were studied by ESR spectroscopy. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2333–2340, November, 1998.     

Synthesis,characterization, crystal structure and thermal analysis of a copper(II) mononuclear compound with 2,6- bis (3,5-dimethyl- N -pyrazolyl)pyridine (bdmpp) and selenocyanate as ligands

A single crystal of the copper(II) compound, [Cu(bdmpp)(SeCN)₂], 2, was obtained and its crystal structure was determined by X-ray diffraction methods. The complex was characterized by elemental, thermal and FTIR analysis. The FTIR analysis of the complex clearly shows the SeCN peaks at 2096 and 2061?cm^?1 which did not exist in the free organic ligand (bdmpp). X-ray analysis showed that 2 crystallized in the monoclinic space group P2₁/c. Cu(II) has a distorted trigonal bipyramidal coordination involving three N atoms from the ligand and two N atoms from the selenocyanate group.     

Diastereospecific and diastereoselective syntheses of Ruthenium(II) complexes using N,N' bidentate ligands aryl-pyridin-2-ylmethyl-amine ArNH-CH2-2-C5H4N and their oxidation to imine ligands

Coordination of N,N' bidentate ligands aryl-pyridin-2-ylmethyl-amine ArNH-CH2-2-C5H4N 1 (Ar = 4-CH3-C6H4, 1a; 4-CH3O-C6H4, 1b; 2,6-(CH3)2-C6H3, 1c; 4-CF3-C6H4, 1d) to the moieties [Ru(bipy)2]2+, [Ru(eta5-C5H5)L]+ (L = CH3CN, CO), or [Ru(eta6-arene)Cl]2+ (arene = benzene, p-cymene) occurs under diastereoselective or diastereospecific conditions. Detailed stereochemical analysis of the new complexes is included. The coordination of these secondary amine ligands activates their oxidation to imines by molecular oxygen in a base-catalyzed reaction and hydrogen peroxide was detected as byproduct. The amine-to-imine oxidation was also observed under the experimental conditions of cyclic voltammetry measurements. Deprotonation of the coordinated amine ligands afforded isolatable amido complexes only for the ligand (1-methyl-1-pyridin-2-yl-ethyl)-p-tolyl-amine, 1e, which doesn't contain hydrogen atoms in a beta position relative to the N-H bond. The structures of [Ru(2,2'-bipyridine)2(1b)](PF6)2, 2b; [Ru(2,2'-bipyridine)(2)(1c)](PF6)2, 2c; trans-[RuCl2(COD)(1a)], 3; and [RuCl2(eta6-C6H6)(1a)]PF6, 4a, have been confirmed by X-ray diffraction studies.     

Atom transfer as a preparative tool in coordination chemistry. Synthesis and characterization of Cr(V) nitrido complexes of bidentate ligands

The transfer of a terminal nitrido ligand from Mn(V)(N)(salen) to Cr(III) complexes is explored as a new preparative route to Cr(V) nitrido complexes. Reaction of Mn(V)(N)(salen) with labile CrCl(3)(THF)(3) in acetonitrile solution precipitates [Mn(Cl)(salen)].(CH(3)CN) and yields a solution containing a mixture of Cr(V) nitrido species with only labile auxiliary ligands. From this solution Cr(V) nitrido complexes with bidentate monoanionic ligands can be obtained in high yields. Five coordinate complexes of 8-hydroxoquinolinate (quin), 1,3-diphenylpropane-1,3-dionate (dbm), and pyrrolidinedithiocarbamate (pyr-dtc) have been structurally characterized: Cr(N)(quin)(2) (1) crystallizes as compact orange prisms in the triclinic space group P with cell parameters a = 7.2450(6) A, b = 8.1710(4) A, c = 13.1610(12) A, alpha = 80.519(6) degrees, beta = 75.721(7) degrees, gamma = 75.131(5) degrees, V = 725.47(10) A(3), Z = 2. Cr(N)(dbm)(2) (2) crystallizes as green rhombs in the orthorhombic space group Pbca with cell parameters a = 14.6940(6) A, b = 16.4570(18) A, c = 19.890(3) A, V = 4809.8(8) A(3), Z = 8. Cr(N)(pyr-dtc)(2) (3) crystallizes as orange prisms in the monoclinic space group P21/c with cell parameters a = 14.8592(14) A, b = 8.5575(5) A, c = 11.8267(12) A, beta = 106.528(7) degrees, V = 1441.7(2) A(3), Z = 4. Complexes 2 and 3 represent new coordination environments for first row transition metal nitrido complexes. The d-orbital energy splitting in these systems with relatively weak equatorial donors differs significantly from the pattern in vanadyl and the previously known first row transition metal nitrido complexes. The d(x)2(-)(y)2 orbital in 2 and 3 is lower in energy and well resolved from the M-N pi orbitals [d(zx),d(yz)].