Photochemistry of Dihydrido(hydrotris(3,5-dimethylpyrazolyl)borato)(Z-cyclooctene)iridium. Synthetic Intermediates and Mechanism of the Photochemical Formation of Hydridophenyl(hydrotris(3,5-dimethylpyrazolyl)borato)(trimethyl phosphite)iridium

The photolysis of a benzene solution of [Tp(Me2)IrH(2)(COE)], 1 (Tp(Me2) = hydrotris(3,5-dimethylpyrazolyl)borate, COE = Z-cyclooctene), in the presence of P(OMe)(3), gives the stable novel complex [Tp(Me2)IrH(C(6)H(5))(P(OMe)(3))], 3a. The photochemical syntheses of [Tp(Me2)IrH(2)(P(OMe)(3))], from 1 and P(OMe)(3) in diethyl ether, and [Tp(Me2)IrH(2)(CH(2)=CHCOO(t)Bu)], from 1 in tert-butyl acrylate, are also reported. The above reactions and several experiments using C(6)D(6) and P(OCD(3))(3) show that, in all cases, the primary photoproduct is the 16-electron, five-coordinate iridium(III) intermediate {Tp(Me2)IrH(2)}, 6a, produced by loss of COE from 1. The above experiments also allow the postulation of a mechanistic pathway for the formation of 3a which involves the oxidative addition of an aromatic C-H bond by 6a. Furthemore, the photochemical reaction of 1 in the presence of P(OCD(3))(3) shows that, under the reaction conditions used, oxidative addition of C-H bonds of P(OMe)(3) and of coordinated Tp(Me2)-ligands, presumably, to the intermediates 6a and {Tp(Me2)IrH(C(6)H(5))}, also occurs. Thus, coordinatively unsaturated iridium(III) species readily activate C-H bonds.     

Mono- and bis-alkoxides of tris(3,5-dimethylpyrazolyl)borato molybdenum and tungsten nitrosyls

The complexes [ML^*(NO)Cl(OR)] {L^* = HB(3,5-Me₂C₃HN₂)₃; M= Mo, R = CH₂CH₂X, X = Cl, OMe or OEt; (CH₂)_nOH, n = 2, 5, 6; M = W, R = CH₂CH₂X, X = Cl, OMe or OEt; (CH₂)_nOH, n = 2–6; CH₂(CF₂)₃CH₂OH; CHMeCH₂CMe₂OH} and [ML^*(NO)(OR)₂] {M = Mo, R = CH₂CH₂X, X = Cl, OMe or OEt; (CH₂)_nOH, n = 2–6; M = W,R = CH₂CH₂X, X= Cl, OMe or OEt; (CH₂)_nOH, n = 2,4–6; CH₂(CF₂)₃CH₂OH} have been prepared from [ML^*(NO)Cl₂] and the appropriate alcohol in the presence of NEt₃ or NaCO₃, and have been characterized by IR, ¹H NMR and mass spectroscopy.     

The synthesis and structure of bis(acetonitrile)nitrosyl tris(3,5-dimethylpyrazolyl)borato molybdenum hexafluorophosphate

Summary Treatment of [Mo{HB(3,5-Me₂C₃HN₂)₃}(NO)I₂] with one or two moles of AgPF₆ in acetonitrile afforded the paramagnetic (one unpaired electron) complex [Mo{HB(3,5-Me₂C₃NH₂)₃}(NO)(NCMe)₂][PF₆]. The structure of this complex was determined crystallographically, and the six-coordinate geometry of the complex cation confirmed.     

Mono and dinuclear hydrotris(3,5-dimethylpyrazolyl)borato tantalum complexes

In an effort to obtain suitable starting materials, the synthesis and crystal structure of hydrotris(3,5-dimethylpyrazolyl)borato (Tp^Me2) tantalum(III) complexes are reported. Reaction of KTp^Me2 with [TaCl₂(tht)]₂(μ-Cl)₂(μ-tht) (1) (tht=tetrahydrothiophene) gives the X-ray characterized unsymmetrical (Tp^Me2Ta)(TaCl₃)(μ-Cl₂)(μ-tht) (2) in fair yield. This doubly bonded TaTa complex [2.6791(5) Å, diamagnetic, 18e per Ta] is a rare example of an unsymmetrical Ta₂X₆L₃ complex. The X-ray structure of Tp^Me2TaCl₂(PhCCMe) (3) is also reported. It has the (4e)-alkyne in the symmetry plane of the molecule. The trans effects of tht and phenylpropyne are discussed. 1 is inert towards the reaction with a second equivalent of KTp^Me2.     

A convenient synthetic route to half-sandwich rhodium(III) complexes of the tripodal ligand tris(3,5-dimethylpyrazolyl)methane

The synthesis of the complex [RhCl3tpm*], (1), (tpm*= tris(3,5-dimethylpyrazolyl)methane) is reported. This complex is a suitable starting material for the synthesis of heteroleptic half-sandwich complexes: it has been used to synthesise the complexes; [RhCl(bpy)tpm*][(PF6)2][2][(PF6)2](bpy = 2,2'-bipyridyl), [RhCl(phen)tpm*][(PF6)2][3][(PF6)2]. (phen = 1,10-phenanthroline), [RhCl2(py)tpm*][(PF6)], [4][(PF6)2], (py = pyridine), and[RhCl(py)2tpm*][(PF6)2], [5][(PF6)2]. The structures of [2][(PF6)2], [33][(PF6)2], [4][(PF6)2], and [5][(PF6)2] have been determined by X-ray crystallography. The electrochemical and photophysical properties of these new compounds have also been investigated.     

Rhenium(I) carbonyl complexes derived from tris(3,5-dimethylpyrazolyl)borate ion

Treatment of [Re(CO)₄Cl]₂ with K[HB(3,5-Me₂C₃HN₂)₃] giving Re{HB(3,5-Me₂C₃HN₂)₃} (CO)₃ and Re(3,5-Me₂C₃HN₂)₂(CO)₃Cl, and bromination of the former to give Re{HB(3,5-Me₂-4-BrC₃N₂)₃}(CO)₃, without displacement of CO, is described.     

Alkoxy,amido and thiolato complexes of tris (3, 5-dimethylpyrazolyl)borato(nitrosyl) molybdenum fluoride,chloride and bromide

The complexes Mo{HB(Me₂pyz)₃}(NO)XY {HB(Me₂pyz)₃  HB(3, 5-Me₂C₃HN₂)₃; X=Y=F, Cl or Br; X=F, Y=OEt, NHMe or SBuⁿ; X=Cl, Y=NHR (R=Me Et, Buⁿ, Ph, p-MeC₆H₄), NMe₂ and SR (R=Buⁿ, C₆H₁₁, CH₂Ph, Ph); X=Br, Y=NHMe, NMe₂ and SBuⁿ} have been prepared and characterised spectroscopically. Their properties are generally similar to those of their iodo-analogues.     

Kinetics of substitution at [tris(3,5-dimethylpyrazolyl)-hydroborato]molybdenum nitrosyl dihalides by alcohols and by aniline

The kinetics of substitution by alcohols and by aniline at [tris(3,5-dimethylpyrazolyl)hydroborato]molybdenum nitrosyl dihalides in toluene solution at 298.2 K and at atmospheric pressure are reported and interpreted in terms of an associative mechanism.

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The co-ordination chemistry of tris(3,5-dimethylpyrazolyl)methane manganese carbonyl complexes: synthetic, electrochemical and DFT studies

The tricarbonyl [Mn(CO)(3){HC(pz')(3)}][PF(6)] 1(+)[PF(6)](-) (pz' = 3,5-dimethylpyrazolyl) reacts with a range of P-, N- and C-donor ligands, L, in the presence of trimethylamine oxide to give [Mn(CO)(2)L{HC(pz')(3)}](+) {L = PEt(3)3(+), P(OEt)(3)4(+), P(OCH(2))(3)CEt 5(+), py 6(+), MeCN 7(+), CNBu(t)8(+) and CNXyl 9(+)}. The complex [Mn(CO)(2)(PMe(3)){HC(pz')(3)}](+)2(+) is formed by reaction of 7(+) with PMe(3). Complexes 2(+) and 6(+) were structurally characterised by X-ray diffraction methods. Reaction of 7(+) with half a molar equivalent of 4,4'-bipyridine gives a purple compound assumed to be the bridged dimer [{HC(pz')(3)}Mn(CO)(2)(μ-4,4'-bipy)Mn(CO)(2){HC(pz')(3)}](2+)10(2+). The relative electron donating ability of HC(pz')(3) has been established by comparison with the cyclopentadienyl and tris(pyrazolyl)borate analogues. Cyclic voltammetry shows that each of the complexes undergoes an irreversible oxidation. The correlation between the average carbonyl stretching frequency and the oxidation potential for complexes of P- and C-donor ligands is coincident with the correlation observed for [Mn(CO)(3-m)L(m)(η-C(5)H(5-n)Me(n))]. The data for complexes of N-donor ligands, however, are not coincident due to the presence of a node (and phase change) between the metal and the N-donor in the HOMO of the complex as suggested by preliminary DFT calculations.     

Networks based on hydrogen-bonds containing phosphorus anions and tris(3,5-dimethylpyrazolyl)borate nickel(II) moieties

Five structural kinds of nickel hydrogen-bonded networks containing hydrotris(3,5-dimethylpyrazolyl)borate ligands (Tp^∗) have been elucidated by X-ray diffraction, [Tp^∗Ni(OH₂)₃][(p-NO₂C₆H₄O)₂PO₂] (4), [Tp^∗Ni(OH₂)₃][Me₂PO₂]·Me₂P(O)OH (5), [Tp^∗Ni(OH₂)₃][(nBuO)₂PO₂]·0.5H₂O (6), [(Hpz)Tp^∗Ni(OH₂)₂][(Ph)PO₂OH] (7) and [Tp^∗Ni(OH₂)₂(Me₂PO₂)] (8). The most relevant supramolecular feature of complexes 4-8 is all of them form coordination networks based on hydrogen bonds between water molecules and phosphate, phosphonate or phosphinate anions. These hydrogen bonds are formed within the monomer units in addition to connect monomers along the chains. Their behaviors in solution were investigated by one- and two-dimensional ¹H NMR techniques.     

Complexes of heteroscorpionate trispyrazolylborate ligands. Part XII. Variable hapticity of hydrobis(3-phenyl-5-isopropylpyrazolyl)(3,5-dimethylpyrazolyl)borate in its rhodium(I) complexes with COD and NBD

The structure of Tp″Rh(NBD) complex was determined by X-ray crystallography (Tp″=hydrobis(3-phenyl-5-isopropylpyrazolyl)(3,5-dimethylpyrazolyl)borate, NBD=2,5-norbornadiene). The Tp″ was found to be κ³ coordinated to rhodium(I). Two independent molecules of Tp″Rh(NBD) were found in triclinic crystals with Rh–N(pz) distances in the region of 2.113(3)–2.307(3) Å. On the other hand the same Tp″ ligand was demonstrated to be coordinated in κ² fashion in Tp″Rh(COD) (COD=1,5-cyclooctadiene) by variable temperature 1-D and 2-D ¹H NMR measurements. The intramolecular exchange between coordinated and uncoordinated 3-phenyl-5-isopropylpyrazolyl residues occurs with ΔG^≠=42.2 kJ/mol as it was calculated from the ¹H NMR studies.     

Mono- and bi-metallic complexes based on redox-active tris(3,5-dimethylpyrazolyl)borato-molybdenum nitrosyls,part III.(1) Complexes containing meta-substituted benzene- and naphthalenediols or -diamines

Summary The complexes [MoL^*(NO)Cl(YC₆H₄YH-m)] (Y = O or NH), [MoL^*(NO)Cl(YC₁₀H₆YH-1,5)], (Y = O or NH), [MoL^*(NO)Cl(OC₁₀H₆OH-2,7)], [{MoL^*(NO)Cl}₂(XC₆H₄Y-m)] (X=Y=O, NH or S; X=O, Y=NH), [{MoL^*(NO)-C1}₂(YC₁₀H₆Y-1,5)] (Y=O or NH) and [{MoL^*(NO)Cl₂-(OC₁₀H₆-2,7)] have been prepared and studied by cyclic voltammetry. The monometallic species undergo a reversible oneelectron reduction, whereas the bimetallics undergo two oneelectron reductions. A comparison of E_1/2 (E_1/2(1)-E_1/2(2)) values for those new species with those obtained frompara- substituted analogues and bimetallics containing extended bridges YC₆H₄ZC₆H₄Y (e.g. Z = S or CH₂CH₂) established that the interaction between the redox centres in these new species is intermediate (YC₆H₄Y-m; NHC₁₀H₆NH-1,5) or weak (OC₁₀H₆O).In earlier papers^1,2 we have described the synthesis and electrochemical properties of a series of mono- and bi-metallic complexes of the type [MoL^*(NO)X(YC₆H₄YH)], [MoL^*(NO)X}₂(YC₆H₄Y)] and [{MoL^*(NO)X}₂(YC₆H₄-ZC₆H₄Y)] [L^*=tris(3,5-dimethylpyrazolyl)borate, HB(Me₂C₃HN₂)₃] where the arene ring ispara-substituted (X=Cl or I while Y=O, S or NH and Z = nothing, CH₂, CH₂CH₂, S, SO₂ or O). We have shown that the E_1/2-values of these species are dependent on X and Y, and that the bimetallic species undergo two one-electron reduction processes.We have established that there is strong interaction between the redox centres in bimetallics bridged byp-YC₆H₄Y, but that weak-to-negligible interaction occurs in those species containing YC₆H₄ZC₆H₄Y bridges. In this paper we describe our investigations ofmete-substituted bridging systems,m-YC₆H₄Y, and comparable systems containing naphthalene bridges,e.g. 1,5- or 2,7-YC₁₀H₂Y. From these studies we hoped to establish the extent of interaction between the two redox centres and how this compared to thepara-substituted arene counterparts.     

三(3,5-二甲基吡唑)氢合硼酸钾及双[三(3,5-二甲基吡唑)]氢合硼酸根合铜(II)的合成和晶体结构

为研究吡唑硼类配体的配位行为, 合成了三(3,5-二甲基吡唑氢合硼酸钾[KHB(C~5H~7N~2)~3], 简称(KL)和双[三(3,5-二甲基吡唑)氢合硼酸根]合铜(II){Cu[HB(C~5H~7N~2)~3]~2}, 简称(CuL~2), 并测定了它们的晶体结构。化合物KL属空间群P2~1/n。a=1.0527(8), b=0.9464(3), c=1.7730(9)nm, β=94.51(5)°,Z=4, D~c=1.268g.cm~-~3, R=0.079。化合物CuL~2属空间群PI, a=0.8768(1),b=1.0170(2), c=1.0859(1)nm, α=62.45(1),β=83.78(1), γ=78.52(1)°, Z=2,D~c=1.298 g.cm~-~3, R=0.062。晶体结构测定结果表明: 化合物KL由钾离子和配体负离子组成, K~+与配体L中的B原子相距0.3634nm, 在配体负离子中B原子与三个吡唑环的N原子及H原子形成四面体构型。化合物CuL~2由孤立分子组成, 铜离子处于分子的对称中心且与两个配体分子中的六个N原子形成六配位的八面体构型, 并表现出明显的Jahn-Teller效应。     

Allylic C-H bond activation and functionalization mediated by tris(oxazolinyl)borato rhodium(I) and iridium(I) compounds

Allylic C-H bond oxidative addition reactions, mediated by tris(oxazolinyl)borato rhodium(I) and iridium(I) species, provide the first step in a hydrocarbon functionalization sequence. The bond activation products To(M)MH(η(3)-C(8)H(13)) (M = Rh (1), Ir (2)), To(M)MH(η(3)-C(3)H(5)) (M = Rh (3), Ir (4)), and To(M)RhH(η(3)-C(3)H(4)Ph) (5) (To(M) = tris(4,4-dimethyl-2-oxazolinyl)phenylborate) are synthesized by reaction of Tl[To(M)] and the corresponding metal olefin chloride dimers. Characterization of these group 9 allyl hydride complexes includes (1)H-(15)N heteronuclear correlation NMR experiments that reveal through-metal magnetization transfer between metal hydride and the trans-coordinated oxazoline nitrogen. Furthermore, the oxazoline (15)N NMR chemical shifts are affected by the trans ligand, with the resonances for the group trans to hydride typically downfield of those trans to η(3)-allyl and tosylamide. These group 9 oxazolinylborate compounds have been studied to develop approaches for allylic functionalization. However, this possibility is generally limited by the tendency of the allyl hydride compounds to undergo olefin reductive elimination. Reductive elimination products are formed upon addition of ligands such as CO and CN(t)Bu. Also, To(M)RhH(η(3)-C(8)H(13)) and acetic acid react to give To(M)RhH(κ(2)-O(2)CMe) (8) and cyclooctene. In contrast, treatment of To(M)RhH(η(3)-C(3)H(5)) with TsN(3) (Ts = SO(2)C(6)H(4)Me) gives the complex To(M)Rh(η(3)-C(3)H(5))NHTs (10). Interestingly, the reaction of To(M)RhH(η(3)-C(8)H(13)) and TsN(3) yields To(M)Rh(NHTs)(H)OH(2) (11) and 1,3-cyclooctadiene viaβ-hydride elimination and Rh-H bond amination. Ligand-induced reductive elimination of To(M)Rh(η(3)-C(3)H(5))NHTs provides HN(CH(2)CH=CH(2))Ts; these steps combine to give a propene C-H activation/functionalization sequence.