Synthesis and characterisation of a series of 1,2-phenylenedioxoborylcyclopentadienyl-metal complexes [Ti(IV), Zr(IV), Hf(IV), La(III), Ce(III), Yb(III), Sn(II) and Fe(II)]

The preparation of a series of 1,2-phenylenedioxoborylcyclopentadienyl-metal complexes is described. These are of formula [M{η⁵-C₅H₄(BX)}Cl₃] [M = Ti and X = CAT (2a), CAT^t (2b) or CAT^tt (2c); X = CAT^tt and M = Zr (4a) or Hf (4b)], [M{η⁵-C₅H₄(BX)}₂Cl₂] [M = Zr, X = CAT (3a) or CAT^t (3c); or M = Hf, X = CAT (3b) or CAT^t (3d)], [M{(μ-η⁵-C₅H₃BCAT)₂ SiMe₂}Cl₂] [M = Zr (5a) or Hf (5b)], [M{η⁵-C₅H₃(BCAT)₂}Cl₃] [M = Zr (6a) or Hf (6b)], [M{η⁵-C₅H₄BCAT}₃(THF)] [M = La (7a), Ce (7b) or Yb (7c)], [Sn{η⁵-C₅ H₄(BCAT^t)}Cl](8) and [Fe{η⁵-C₅H₄(BCAT^t)}₂] (9). The abbreviations refer to BO₂C₆H₄-1,2 (BCAT) and the 4-Bu^t (BCAT^t) and the (BCAT^tt) analogues. The compounds 2a-9 have been characterised by microanalysis, multinuclear NMR and mass spectra. The single crystal X-ray structure of the lanthanum compound 7a is presented.     

Some new derivatives of organozirconium(IV) and organotitanium(IV) with thiophenecarboxylic acids

The complexes of the type Cp₂M(3-TC)Cl, Cp₂M(3-TC)₂, Cp₂M(3-TA)Cl, Cp₂M(3-TA)₂, Cp₂M(2-TB)Cl, Cp₂M(2-TB)₂ [where Cp = cyclopentadienyl, M = Zr or Ti] were synthesized by the reactions of dichlorobis(cyclopentadienyl)zirconium(IV) and dichlorobis(cyclopentadienyl)titanium(IV) with 3-thiophenecarboxylic acid (3-TCH), 3-thiopheneacetic acid (3-TAH) and 2-thiophenebutyric acid (2-TBH) respectively in different stoichiometric ratios. The new complexes were characterized by their elemental analysis, ¹H NMR, IR, and electronic spectral data.     

Titanium, zirconium and hafnium halide complexes of trithioether and triselenoether ligands

The reaction of TiX₄(X=Cl or Br) with the tripodal ligands MeC(CH₂SMe)₃ or MeC(CH₂SeMe)₃, (L³) in anhydrous n-hexane or CH₂Cl₂ produced the extremely moisture sensitive complexes [TiX₄(L³)]. These were characterised by microanalysis, IR, UV-Vis and variable temperature ¹H,¹³C{¹H} and ⁷⁷Se NMR spectroscopy. The NMR studies showed that in solution in CH₂Cl₂ the complexes contain L³ bound as bidentates, and that pyramidal inversion and exchange between the free and coordinated chalcogen donors is rapid at room temperature. Ligand dissociation/exchange increases TiCl₄<TiBr₄ and MeC(CH₂SMe)₃<MeC(CH₂SeMe)₃ and attempts to isolate TiI₄ analogues were unsuccessful. The reactions of [MCl₄(Me₂S)₂] (M=Zr or Hf) with (L³) in anhydrous CH₂Cl₂ produces white or cream 7-coordinate [MCl₄(L³)], which are insoluble in chlorocarbon solvents. The reactions of TiX₄ (X=Cl, Br or I) with the trithia-macrocycles [9]aneS₃ and [10]aneS₃ produced [TiX₃([n]aneS₃)]X, whilst reaction of TiCl_4, SbCl₅ and [9]aneS₃ in anhydrous CH₂Cl₂ gave [TiCl₃([9]aneS₃)]SbCl₆. Spectroscopic studies suggest these macrocyclic compounds contain 6-coordinate cations, [TiX₃([n]aneS₃)]⁺ (n=9 or 10) but with Zr and Hf the complexes [MCl₄([n]aneS₃)] are 7-coordinate and neutral.     

Synthesis,Spectral and Antibacterial Studies of Binuclear Titanium(IV) / Zirconium(IV) Complexes of Piperazine Dithiosemicarbazones

The reactions of mono(cyclopentadienyl)titanium(IV) trichloride and bis(cyclopentadienyl)titanium(IV)/ zirconium(IV) dichloride with a new class of dithiosemicarbazone, derived by condensing piperazine dithiosemicarbazide with benzaldehyde (L₁H₂), 2-chlorobenzaldehyde (L₂H₂), 4-nitrobenzaldehyde (L₃H₂) or salicylaldehyde (L₄H₄) have been studied and different types of binuclear products, viz. [{CpTiCl₂}₂L], [{Cp₂MCl}₂L], ((L=L₁, L₂ or L₃), [{CpTiCI}₂L₄] and [{Cp₂M}₂L₄] (M=Yi or Zr), have been isolated. Tentative structures are proposed for these complexes based upon elemental analyses, electrical conductance, magnetic moment and spectral (electronic, IR, ¹H and ¹³C NMR) data. Attempts have been made to establish a correlation between antibacterial activity and the structures of the products.     

Synthesis of fac-[Os(CO)3(L)Me2] (L = THF or MeCN) and some reactions with PPh3 and trityl salts

The reaction of cis-[Os(CO)₄Me₂] with Me₃NO in the THF or MeCN yields the complexes fac-[Os(CO)₃(L)Me₂] (where L = THF or MeCN). Whereas the THF complex is unstable and only characterised spectroscopically, fac-[Os(CO)₃(MeCN)Me₂] has been isolated as a white solid and fully characterized by both analytical and spectroscopic methods. These complexes fac-[Os(CO)₃(L)Me₂] are shown to be useful intermediates. Thus, reaction with PPh₃ gives fac-[Os(CO)₃(PPh₃)Me₂] in good yield.Reactions of fac-[Os(CO)₃(L)Me₂] (L = CO or MeCN) with CPh₃PF₆ or B(C₆F₅)₃ have been investigated. Whereas cis-[Os(CO)₄Me₂] showed no reaction with either CPh₃PF₆ or B(C₆F₅)₃, the reaction of fac-[Os(CO)₃(MeCN)Me₂] with CPh₃PF₆ in CH₂Cl₂ occurred over 16 h at room temperature to give an unstable cationic product and CPh₃Me. The reaction was monitored by both IR and NMR spectroscopies. When this reaction of fac-[Os(CO)₃(MeCN)Me₂] was carried out in the presence of a trapping ligand such as MeCN, the stable cationic product [Os(CO)₃(MeCN)₂Me]⁺ could be isolated and identified spectroscopically.     

Electronic absorption and MCD spectra for octacyanometallate complexes M(CN)8, M=Mo(IV), W(IV), n=4 and Mo(V), W(V), n=3

Electronic absorption and 8.0 T magnetic circular dichroism (MCD) spectra are reported for M(CN)₈ ⁴⁻, M=Mo(IV) and W(IV), in aqueous solution and M(CN)₈ ³⁻, M=Mo(V) and W(V), in acetonitrile solutions. In addition some absorption and MCD spectra are reported for the M(CN)₈ ³⁻ ions embedded in thin poly methyl methacrylate (PMMA) plastic films at temperatures from 295 to 10 K. The temperature dependence of the MCD spectra confirms the presence of C terms. The solution and PMMA spectra for the both Mo and W complexes in either the IV or V oxidation states are remarkably similar to each other for the same oxidation state and are interpreted within a D_2d structural framework for the isotropic environment. The weak bands below 3.0 μm⁻¹ (1 μm⁻¹=10⁴ cm⁻¹) for the M(IV) complexes are assigned as metal-localized ligand field (LF) transitions. LF transitions are also suggested for weaker unresolved absorption between 3.0 and 3.6 μm⁻¹ for the M(V) ions. The intense bands above 3.6 μm⁻¹ for M(IV) and 4.6 μm⁻¹ for M(V) complexes are interpreted as metal to ligand charge transfer (MLCT) from the metal b₁(x²−y²) HOMO to CN⁻-based π * orbitals. The prominent intense bands observed below 4.5 μm⁻¹for the M(V) complexes are assigned as ligand to metal charge transfer (LMCT) from occupied non-bonding or weakly π bonding CN⁻ orbitals to the half-filled b₁(x²−y²) HOMO.     

Alkylimido complexes of titanium(IV)

TiCl₄ reacts with t-butylamine in benzene to give [Ti(NCMe₃)Cl₂(NH₂CMe₃)₂]_x and t-butylamine hydrochloride. The IR spectrum indicates both c/s and trans metal dichlorides (300; and 308, 208 cm⁻¹). In the ¹³C NMR spectrum the t-butylimido quaternary carbon resonance occurs at 72.1 ppm. A dimeric structure incorporating symmetric t-butylimido bridges is proposed. TiCl₄ in benzene react under reflux with two equivalents of Me₃SiNHCMe₃ to give [Ti(NCMe₃)Cl₂(NH₂CMe₃)]_x and with iso-propylamine and ethylamine to give complexes of the form [Ti(NR)Cl₂(NH₂R)₂]_x. Broad bands below 800 cm⁻¹ in the IR spectra suggest polymeric MNM bridges. For [Ti(NCHMe₂)Cl₂(NH₂CHMe₂)]_x the iso-propylimido CH resonance in the ¹³C NMR spectrum occurs at 67 ppm. [Ti(NCMe₃)Cl₂(NH₂CMe₃)₂]₂ reacts with L=bipy or tmed to give [Ti(NCMe₃)Cl₂(L)]₂, and TiCl₄ reacts with two equivalents of Me₃SiNHCMe₃ in benzene and then tmed to give [Ti(NCMe₃)Cl₂(tmed)]₂. The ¹³C NMR spectrum shows the t-butylimido quaternary carbon resonance at 73.5 ppm and the tmed resonances are chemically equivalent. A dimeric μ-NCMe₃ bridging structure is proposed for the complex.     

N,N-dimethylcarbamato complexes of zinc

By reaction of Zn₄O(O₂CNMe₂)₆ (1) with [NH₂Me₂][O₂CNMe₂] in toluene as medium, the homoleptic zinc compound [Zn(O₂CNMe₂)₂] (2) was obtained, which reverted back to the tetranuclear μ-oxo derivative by controlled hydrolysis. The reaction of ZnO in MeCN with an excess of [NH₂Me₂][O₂CNMe₂] in concentrated solution produced high yields of [Zn(O₂CNMe₂)₂] (2) or [NH₂Me₂][Zn₂(O₂CNMe₂)₅] · xMeCN, 3 · xMeCN, x = 1 or 2, depending on the experimental conditions.     

Optical activity of dimolybdenum complex induced by chiral,chelating diamine ligand; syntheses and structures of [Mo2(O2CCF3)2(S,S-dach)2(CH3CN)2][BF4]2 and [Mo2(O2CCF3)2(R,R-dach)2(CH3CN)2][BF4]2 (dach=1,2-diaminocyclohexane)

The first structurally characterized, quadruply bonded complexes containing chiral diamine ligands, [Mo₂(O₂CCF₃)₂(S,S-dach)₂(CH₃CN)₂][BF₄]₂ (1), and [Mo₂(O₂CCF₃)₂(R,R-dach)₂(CH₃CN)₂][BF₄]₂ (2); (dach=1,2-diaminocyclohexane) were prepared by reactions of [Mo₂(O₂CCF₃)₂(CH₃CN)₆][BF₄]₂ with S,S-dach and R,R-dach, respectively, in CH₃CN. Their UV–Vis and circular dichroism (CD) spectra have been recorded and their structures determined by X-ray crystallography. Crystals of complexes 1 and 2 conform to the space groups P2 with two independent half molecules in the asymmetric unit. The two molecules have a similar structure consisting of a Mo₂ unit bridged by two cis-trifluoroacetate ligands and chelated by two dach ligands. Two acetonitrile molecules are coordinated to the Mo centers along the MoMo bond. The absorption wavelength at 507 nm for both 1 and 2 can be assigned to δ_xy→δ_xy* transitions. The solution CD spectra of these two complexes show two prominent bands at 525 and 385 nm and form mirror images of each other. The solid CD spectra of complexes 1 and 2 show marked red-shift in the absorption energies as compared with those measured in solution. The one-electron static coupling mechanism was invoked to explain the CD spectra for these complexes and the second lowest energy bands were assigned to be δ_xy→δ_x²−y² transitions.     

Vanadocene complexes of amino acids containing secondary amino group: The first evidence of O,O-bonded carboxylic group to vanadocene(IV) moiety

Reaction of vanadocene dichlorides (Cp₂VCl₂ and (η⁵-C₅H₄Me)₂VCl₂) with amino acids containing secondary amino groups gives three types of complexes: a) compounds with N,O-bonded amino acid, b) O-bonded amino acids and c) O,O-bonded amino acid. The complexes with N,O-bonded amino acid and O-bonded amino acids were observed in the case of l-proline and N-methylglycine (NMG). Reactions with N-phenylglycine (NPG) give O,O-chelates as the sole products. All three types of the complexes were characterized by spectroscopic methods. Structures of [(η⁵-C₅H₄Me)₂V(O-Pro)][BPh₄], [Cp₂V(O-Pro)₂][PF₆]₂, [Cp₂V(N,O-NMG)][BPh₄]·MeOH, [(η⁵-C₅H₄Me)₂V(N,O-NMG)][BPh₄]·MeOH, [Cp₂V(O-NMG)₂][Cl]₂·2H₂O, [(η⁵-C₅H₄Me)₂V(O-NMG)₂][Cl]₂·H₂O and [(η⁵-C₅H₄Me)₂V(O,O-NPG)][BPh₄] were determined by X-ray crystallography.     

Preparation,structure and properties of dicyano silver complexes of the M(en)3Ag2(CN)4 and M(en)2Ag2(CN)4 type

Complexes of the M(en)₃Ag₂(CN)₄ (M = Ni, Zn, Cd) and M(en)₂Ag₂(CN)₄ (M = Ni, Cu, Zn, Cd) type were prepared and identified by elemental analysis, infrared spectroscopy, measurement of magnetic susceptibility, and X-ray powder diffractometry. The crystal structures of Ni(en)₃Ag₂(CN)₄ (I) and Zn(en)₂Ag₂(CN)₄ (II) were determined by the method of monocrystal structure analysis. Complex I crystallizes in the space group C2/c, a = 1.2639(5), b = 1.3739(4), c = 1.2494(4) nm, β = 113.25(4)°, D_m = 1.86(1), D_c = 1.86 gcm⁻³ Z = 4, R = 0.0429. The crystal structure of I consists of complex cations [Ni(en)₃]²⁺ and complex anions [Ag(CN)₂]⁻. Complex II crystallizes in the space group I2/m, a = 0.9150(3), b = 1.3308(4), c = 0.6442(2) nm, β = 95.80(3)°, D_m = 2.14(1), D_c = 2.15 gcm⁻³, Z = 2, R = 0.0334. Its crystal structure consists of infinite, positively charged chains of the [-NCAgCNZn- (en)₂]_nⁿ⁺ type and isolated [Ag(CN)₂]⁻ anions. The atoms of Ag are positioned parallely to the z axis and the AgAg distance is equal to 0.3221(2) nm.     

Synthesis,reactions, spectral and magnetic studies of bimetallic alkoxides of cobalt(II) with zirconium(IV)

A bimetallic isopropoxide of cobalt(II) with the formula Co[Zr₂(OPrⁱ)₉]₂, prepared by the reaction of COCl₂ with K[Zr₂(OPrⁱ)₉] in 1:2 molar ratio, has been shown to undergo alcoholysis reactions with graded alcohols (primary, secondary and tertiary) to afford products of the types, Co[Zr₂(OR)₉]₂ (where R = Me, Et, Prⁿ, Buⁿ, Buⁱ and Bu^s) Co[Zr₂(OPrⁱ)₃(OEt)₆]₂, Co[Zr₂(OPrⁱ)₆(OBu^s)₃]₂, CO[Zr₂(OPrⁱ)₃(OBu^s)₆]₂, Co[Zr₂(OPrⁱ)₆(OBu^t)₃]² and Co[Zr₂(OPrⁱ)₃(OR)₆]₂ (where R = Am^t or Bu^t). These derivatives have been characterized by elemental analyses and molecular weight determinations. Infrared, electronic (visible) spectral and magnetic susceptibility measurements suggest a distorted octahedral geometry for these derivatives.     

Reactions of nitrones with transition metal nitrile complexes: cycloaddition, ligand substitution, or hydrolysis

The reaction of nitrones with transition metal nitrile complexes of the type [MCl₂(PhCN)₂] and [MCl₄(MeCN)₂] leads to different products, depending on the metal. Reaction of [PdCl₂(PhCN)₂] with RCHN(Me)O (R=Ph, p-C₆H₄Me) afford Δ⁴-1,2,4-oxadiazoline complexes as products of [2 + 3] cycloaddition of the nitrone across the C≡N bond of the nitrile. The oxophilic transition metal compounds [TiCl₄(MeCN)₂] and [ZrCl₄(MeCN)₂] undergo rapid ligand exchange to form nitrone complexes from which the nitrone can be released without decomposition. The closely related compounds [MoCl₄(MeCN)₂] and [WCl₄(MeCN)₂] mediate the hydrolysis of nitrones to the corresponding aldehydes.     

Synthesis and characterization of [Fe(III)(qsal)2][M(III)(pds)2] (M = Cu, Au)

Salts of the Fe(III) spin crossover cation [Fe^III(qsal)₂]⁺ (qsalH = N-(8-quinolyl)salicylaldimine) and monoanions [M^III(pds)₂]⁻ (M = Cu, Au; pds = pirazine-2,3-diselenolate) with formula [Fe^III(qsal)₂][M^III(pds)₂] were prepared and characterized by single crystal X-ray diffraction and magnetic measurements. These two salts present magnetic properties essentially due to the Fe^III centres in the high-spin state (S = 5/2), and do not have any spin transition.     

Hydroxylation of a methyl group: synthesis of [Cu2(btmmO)2I] and of [Cu2(btmmO)2] containing the novel ligand {bis(trimethylmethoxy)guanidino}propane (btmmO) by copper-assisted oxygen activation

The reaction of the bisguanidine copper(I) compounds [Cu(btmgp)I] and [Cu₂(btmgp)₂][PF₆]₂ with molecular oxygen afforded at low temperatures complexes containing the bis-μ-oxo dicopper(III) core, which is capable to hydroxylate one of the N-CH₃-groups of the {bis(tetramethyl)guanidino}propane ligands. The formation of the novel ligand {bis(trimethylmethoxy)guanidino}propane (btmmO) is reported as it represents the first hydroxylation of a N-methyl group. The products of this reaction are novel alkoxo-bridged binuclear copper complexes, namely [Cu₂(btmmO)₂I]⁺ containing an iodide ion in a novel bridging situation, as well as [Cu₂(btmmO)₂]²⁺ which have been identified in their complex salts and [Cu₂(btmmO)₂][PF₆]₂ · 2MeCN, respectively. Concomitantly, the hydroxo-bridged binuclear copper compounds [Cu₂(btmgp)₂(μ-OH)₂]I₂ and [Cu₂(btmgp)₂(μ-OH)₂][PF₆]₂ are formed as couple products. The formation of the bis-μ-oxodicopper(III) complexes was monitored by UV/Vis-spectroscopy, and the reaction products were characterised by X-ray diffraction, vibrational spectroscopy and elemental analysis.     

Organometallic nickel(II) complexes with dithiophosphate, dithiophosphonate and monothiophosphonate ligands

The hydroxo complex [NBu₄]₂[Ni₂(C₆F₅)₄(μ-OH)₂] reacts with ammonium O,O^′-dialkyldithiophosphates, O-alkyl-p-methoxyphenyldithiophosphonate acids and ammonium O-alkylferrocenyldithiophosphonates in dichloromethane under mild conditions to give, respectively, [NBu₄][Ni(C₆F₅)₂{S(S)P(OR)₂}] (R=Me (1), Et (2), ⁱPr (3)) and [NBu₄][Ni(C₆F₅)₂{S(S)P(OR)Ar}] (Ar=p-MeOC₆H₄, R=Me (4), Et (5), ⁱPr (6); Ar=ferrocenyl; R=Me (7), Et (8), ⁱPr (9)). The monothiophosphonate nickel complexes [NBu₄][Ni(C₆F₅)₂{S(S)P(OR)(ferrocenyl)}] (R=Et (10), ⁱPr (11)) are obtained by reaction of the hydroxo complex with O-alkylferrocenyldithiophosphonate acids. Analytical (C, H, N, S), conductivity, and spectroscopic (IR, ¹H, ¹⁹F and ³¹P NMR, and FAB-MS) data were used for structural assignments. A single-crystal X-ray diffraction study of [NBu₄][Ni(C₆F₅)₂{S(S)P(OMe)(p-MeOC₆H₄)}] (4) and [NBu₄][Ni(C₆F₅)₂{S(O)P(OEt)(ferrocenyl)}] (10) shows that in both cases the coordination around the nickel atom es essentially square planar with NiC₂S₂ and NiC₂SO central cores, respectively.     

Structural models for [M(CO)3(H2O)3]+ (M=Tc,Re): fully aqueous synthesis of technetium and rhenium tricarbonyl complexes of tripodal oxygen donor ligands

The reaction of [M(H₂O)₃(CO)₃]⁺ (M=Tc, Re) with Na[CpCo[PO(OR)₂]₃] (NaL_OR; R=Me, Et) in water produced the compounds M(CO)₃(L_OR), all of which were yellow solids, in yields varying from 55 to 89%. The two compounds M(CO)₃(L_OEt) were structurally characterized by single crystal X-ray crystallography. In both cases, the ligand L_OEt was bound to the metal center in a tridentate fashion utilizing an {OOO} donor set. The ligands L_OR can be used as models for facially coordinated triaqua groups owing to their position in the spectrochemical series. Therefore, these four compounds, M(CO)₃(L_OR), can be considered structural models for [M(H₂O)₃(CO)₃]⁺. Crystal data for Tc(CO)₃(L_OEt) are as follows: molecular formula C₂₀H₃₅CoO₁₂P₃Tc, MW=717.32, monoclinic, a=11.5661(11) Å, b=18.671(2) Å, c=13.7852(13) Å, β=92.770(2)°, V=2973.5(5) Å³, space group P2₁/n, Z=4, final R₁=0.0669, wR₂=0.1361. Crystal data for Re(CO)₃(L_OEt) are as follows: molecular formula C₂₀H₃₅CoO₁₂P₃Re, MW=805.52, monoclinic, a=11.5113(7) Å, b=18.6022(12) Å, c=13.7397(8) Å, β=92.7580(10)°, V=2938.7(3) Å³, space group P2₁/n, Z=4, final R₁=0.0384, wR₂=0.0760.     

The crystal and molecular structure of diethylenetriammonium hexachloro-antimonate(III)

A compound of the type [DenH₃]SbCl₆ (DenH₃ = diethylenetriammonium cation) was prepared and characterized by means of structural and vibrational measurements. The structure consists of monomeric SbCl₆^3? anions and triprotonated diethylenetriam-monium cations. The SbCl₆^3? anion has a strongly distorted octahedral geometry, presenting three short (2.415–2.495 Å) and three long (2.836–3.114 Å) SbCl bonds. The presence of multiple hydrogen bonds, mainly involving the counterion and the three long-bonded chlorine atoms, is considered to be responsible for the octahedral distortion. Vibrational properties of the complex are discussed in the light of its known crystal structure.     

Mixed-ligand compounds incorporating quadruply bonded dimolybdenum(II) core: Syntheses, structures and reactivity studies

Reaction of cis-[Mo₂(OAc)₂(CH₃CN)₆][BF₄]₂ with NP-Et,Me (2-ethyl-3-methyl-1,8-naphthyridine) in acetonitrile provides trans-[Mo₂(NP-Et,Me)₂(OAc)₂(CH₃CN)][BF₄]₂ (1). Partial protonation of 1 by HBF₄·Et₂O in acetonitrile leads to trans-[Mo₂(NP-Et,Me)₂(OAc)(CH₃CN)₃][BF₄]₃ (2). In both compounds, NP-R ligands are arranged in a head-to-head (HH) fashion leaving one of the axial sites vacant. Substitution of acetonitriles by NP-Me (3-methyl-1,8-naphthyridine) in trans-[Mo₂(NP-tz)₂(OAc)(CH₃CN)₂][BF₄]₃ provides trans-[Mo₂(NP-tz)₂(OAc)(NP-Me)][BF₄]₃ (3) with retention of configuration. Fully solvated dimolybdenum(II) compound reacts with NP-NH₂ to provide [Mo₂(NP-NH₂)₂(NP-NH)(CH₃CN)₂][BF₄]₃ (4) in which the NP-NH₂ ligands are trans and arranged in a HH fashion. The deprotonated ligand (NP-NH⁻) binds the dimetal unit utilizing naphthyridine nitrogen and amido nitrogen. Treatment of [Mo₂(NP-tz)₂(CH₃CN)₄][CF₃SO₃]₄ with bpym (2,2′-bipyrimidine) followed by crystallization in air provided an oxo complex [Mo₂(NP-tz)₂(μ₂-O)₂(bpym)₂][CF₃SO₃]₄ (5). Compounds 1-5 have been characterized by a variety of spectroscopic techniques and by X-ray crystallography. The reactivity pattern is rationalized based on ligand labilities and thermodynamic stabilities.     

Syntheses and structural characterization of dicopper(I) bis(diphenylphosphino)acetylene complexes containing tricyclic, cyclic and linear frameworks

The complexes [Cu₂(dppa)₃(CH₃CN)₂][BF₄]₂ (1) and Cu₂(dppa)₃(O₃SCF₃)₂ (2) have been prepared in good yields by treating [Cu(MeCN)₄][BF₄] and [Cu(MeCN)₄][O₃SCF₃], respectively, with Ph₂PCCPPh₂ (abbreviated as dppa) at room temperature. The reaction of 1 with di-2-pyridyl ketone (abbreviated as dpyk) produces [Cu₂(dppa)₂(dpyk)₂][BF₄]₂ (3), and with 1,1′-bis(diphenylphosphino)ferrocene (abbreviated as dppf) produces [Cu₂(dppa)(dppf)₂][BF₄]₂ (4). The molecular structures of 1-4 have been determined by an X-ray diffraction study. Compounds 1 and 2 form a helical Cu₂(dppa)₃ metallatricycle, compounds 3 forms a Cu₂(dppa)₂ metallacycle, and compound 4 contains a linear Cu₂(dppa) skeleton.