Fac Geometry Research Articles

Synthesis and catalytic activity of single-site group V alkoxide complexes for the ring-opening polymerization of ε-caprolactone.

The synthesis, characterization, and ring-opening polymerization (ROP) activity of a family of niobium and tantalum alkoxide catalysts was studied. The final catalysts are made in a two-step synthesis, first by reacting the desired homoleptic metal ethoxide with a phenolketoimine ligand to form a series of synthetic intermediates, followed by reaction with catechol to produce a catalytic platform with a single ethoxide initiator. By using two separate ligands, the electronic properties of the catalyst can be tuned, and the molecular weight of the polymer can be increased. It was found that synthetic intermediates adopted a mer geometry both in solution and in the solid state. This mer geometry was retained for the final catechol derivatives, however in one case, where catechol was substituted for 3-methoxycatechol, the molecule adopted a highly distorted fac geometry. Catalytic ROP activity of the synthetic intermediates and final catechol derivatives with ε-caprolactone was studied through a kinetic analysis. In all seven cases studied the reactions proceeded through the expected coordination-insertion mechanism, following pseudo first-order kinetics and increasing in Mn linearly vs. conversion. The single-initiator catechol derivatives increased the Mn by three times compared to that of the three-initiator synthetic intermediates with little decrease in the overall reaction rate. Both the nature of the ligand and metal were found to impact the rate of reaction in these systems. By switching from an electron donating ligand to an electron withdrawing ligand, the rate was found to nearly double. Tantalum species were faster than their niobium counterparts by ∼3 times in the synthetic intermediates and ∼1.5 times in the catechol derivatives. This observed periodicity supports recent literature findings in this area.

Molybdenum Tricarbonyl Complexes Supported by Linear PNP Ligands: Influence of P‐ and N‐Substituents on Relative Stability, Stereoisomerism and on the Activation of Small Molecules

AbstractSeries of linear tridentate PNPhPR‐ligands (R=Me, Et, Pln, Ph, Cyp, iPr, Cy, tBu) and molybdenum tricarbonyl complexes [Mo(CO)3PNPhPR] (R=Ph, Et, Cyp, iPr, Cy,) were synthesized and characterized using NMR‐, IR‐, and Raman spectroscopy as well as X‐ray crystallography. The influence of the different phosphine donor groups of the PNPhPR ligands on the bonding and activation of CO ligands is investigated. Importantly, all complexes are found to adopt a fac geometry, both in solution and in the solid state. This is in contrast to analogous complexes supported by PNHP ligands. DFT calculations reveal that the phenyl ring at the central amine function is the cause of the preferred geometry, hindering isomerization to a mer geometry.

Titanium ONN-(phenolate) Alkoxide Complexes: Unique Reaction Kinetics for Ring-Opening Polymerization of Cyclic Esters.

The synthesis, characterization, and polymerization kinetics of four new titanium ONN-(phenolate) alkoxide catalysts were studied. Each catalyst is fluxional at room temperature, suggesting the ligand amine arm may be labile, but adopts a fac geometry in solution at low temperature (223 K) and in the solid state. All catalysts are active for the ring-opening polymerization of both ε-caprolactone (CL) and rac-lactide (LA). GPC analysis indicates that the well-known coordination-insertion mechanism is being followed. However, whereas the typical first-order dependence on monomer concentration is observed in CL, an unexpected zeroth-order dependence is observed with LA. This suggests that, in the case of LA, catalyst saturation occurs and a Michaelis-Menten model can be used to explain the kinetics. An initial mechanism is discussed within this model that proposes CL polymerization proceeds by a 7-coordinate intermediate, whereas LA polymerization adopts a 6-coordinate intermediate, facilitated by the ligand amine arm. Attempts to isolate catalyst-monomer intermediates are ongoing.

Complexes of phosphonate and phosphinate derivatives of dipicolylamine

Phospho(i)nate derivatives of dipicolylamine show excellent selectivity for Zn(ii) over alkaline earth metal ions.

Molybdenum(vi) tris(amidophenoxide) complexes

Tris(2-(arylamido)-4,6-di-tert-butylphenoxo)molybdenum(vi) complexes (Rap)3Mo can be prepared either from (cycloheptatriene)Mo(CO)3 and the N-aryliminoquinone, or from MoO2(acac)2 and the aminophenol. In contrast to all other reported unconstrained transition metal tris(amidophenoxide) complexes, the molybdenum complexes show a facial geometry in the solid state. In solution, the fac isomer predominates, though a small amount of mer isomer is detectable at room temperature. At elevated temperature the two species interconvert through Rây-Dutt trigonal twists, which are faster than Bailar twists in this system, presumably because of steric effects of the N-aryl groups. Substituents on the N-aryl ring shift the fac/mer equilibrium of the complex, with more electron-withdrawing substituents generally increasing the proportion of the mer isomer. The preference for fac over mer geometry is thus suggested to be due to enhanced π bonding in the fac isomer. In contrast to analogous catecholate complexes, the tris(amidophenoxide) complexes are not Lewis acidic and are inert to nucleophilic oxidants such as amine-N-oxides.

The Metal or the Ligand? The Preferred Locus for Redox Changes in Oxygen Atom Transfer Reactions of Rhenium Amidodiphenoxides.

The rhenium(V) oxo complex oxo(triphenylphosphine) (bis(3,5-di-tert-butyl-2-phenoxo)amido)rhenium(V), (ONOCat)ReO(PPh3), reacts with molecular oxygen to give triphenylphosphine oxide and the dimeric rhenium(VII) complex fac,anti-(ONOCat)Re(O)(μ-O)2Re(O)(ONOCat). The ONO ligand adopts an unusual fac geometry, presumably to maximize π donation to rhenium; strong π donation is substantiated by the intraligand bond distances (metrical oxidation state = -2.24(9)). Addition of the N-heterocyclic carbene ligand IMes to fac,anti-(ONOCat)Re(O)(μ-O)2Re(O)(ONOCat) cleaves the dimer into monomeric C1-symmetric fac-(ONOCat)ReO2(IMes). The monorhenium(VII) complex is deoxygenated by PMe2Ph to give the rhenium(V) compound (ONOCat)ReO(IMes), which can be independently prepared by ligand substitution of (ONOCat)ReO(PPh3). The degree of stereochemical rigidity exhibited by the dioxo compound, as established by dynamic NMR spectroscopy, excludes the intermediacy of mer-(ONOQ)ReVO2(IMes) in this oxygen atom transfer reaction. Thus, oxygen atom transfer takes place preferentially by direct reduction of the oxorhenium(VII) moiety (classical oxygen atom transfer) rather than through initial internal electron transfer and ligand-centered reduction of an oxorhenium(V)-iminoquinone.

Flexible Syntheses of Tripodal Phosphine Ligands 1,1,2-Tris(diarylphosphino)ethane and Their Ruthenium η5-C5Me5 Complexes

A series of four tripodal polyphosphine ligands (PAr2)2CHCH2PAr2 (1a–d) were synthesized and coordinated to ruthenium to produce the complexes [Ru(η5-C5Me5)((PAr2)2CHCH2PAr2)]PF6 (2a–d) (Ar = phenyl (a), p-tolyl (b), o-tolyl (c), m-xylyl (d)). The 1,1,2-tris(diarylphosphino)ethane compounds were generated in a novel trisubstitution reaction of diarylphosphorylacetaldehyde diethyl acetal, a useful synthetic precursor that was used previously for the synthesis of phosphonium dimers. The tridentate ligands were subsequently combined with the ruthenium(II) precursor Ru(η5-C5Me5)(1,5-COD)Cl, in order to probe the coordination geometry of 1a–d. The resulting complexes 2a–d displayed piano-stool type structures where the phosphine ligands were coordinated in a fac geometry. Despite the large steric bulk of the ligands, as well as the ring strain caused by the formation of a four-membered ring and two five-membered rings with the ruthenium center, complexes 2a–d were quite stable. The ruthenium salts were air and...

Hierarchical self-assembly of heteronuclear co-ordination networks

Two ligands L(1) and L(2) have been prepared which contain a chelating pyrazolyl-pyridine group with a pendant aromatic nitrile (in L(1), a benzonitrile; in L(2), a naphthonitrile). These ligands react with Ag(I) salts to give a range of infinite coordination networks or dimeric 'boxes' in which the pyrazolyl-pyridine chelates and the aromatic nitrile groups both participate in coordination to Ag(I) ions. In contrast, L(1) and L(2) form simple mononuclear tris-chelates [ML(3)](2+) with first-row transition metal dications (M = Co, Ni, Zn) in which the aromatic nitrile groups are pendant such that the complexes can be used as 'complex ligands'. The crystal structures of [M(L(2))(3)](BF(4))(2) are based on solely the mer tris-chelate geometry although in solution (1)H NMR spectroscopy reveals a mixture of both fac and mer isomers of the tris-chelates. Reaction of these with Ag(I) ions allows the interaction of the pendant nitrile groups with Ag(i) ions to generate coordination networks based on [ML(3)](2+) cations being crosslinked by Ag(I) ions. In these networks the [ML(3)](2+) cations have solely the fac geometry and lie on threefold rotation axes with all three pendant nitrile groups coordinated to Ag(I) ions which are three-coordinate. {[AgM(L(2))(3)][BF(4)](3)}(infinity) (M = Co, Ni) consist of two interpenetrated (10,3)a nets which have opposite chirality at the [M(L(2))(3)](2+) centres but are not strictly enantiomorphic as the two nets are not crystallographically equivalent. {[AgNi(L(1))(3)](BF(4))(3)}(infinity) in contrast contains two-dimensional sheets which have a (6,3) net structure of hexagonal rings of alternative Ni(II) and Ag(I) centres; although not interpenetrating, two such adjacent (and enantiomorphic) sheets interact with each other via numerous CH...pi interactions between aromatic ligands. Formation of these structures shows that the differential reactivity of the two binding sites in L(1) and L(2) (pyrazolyl-pyridine, and nitrile) can be used to generate mixed-metal coordination networks in a hierarchical, stepwise manner.

Synthesis and structural characterization of sterically crowded hydridotris(pyrazolyl)borato complexes: Unusual double 1,2-borotropic shift at a titanium centre

The potassium and thallium(I) derivatives of the hydrido-tris(3-Me 2Bz,5-Me-pyrazol-1-yl)borato ligand, K[Tp Me2 Bz,Me] ( 1) and Tl[Tp Me2 Bz,Me] ( 2), are reported. Their reactions with TiCl 4 under mild conditions afforded, after rearrangement of the ligand, recognized as a double 1,2-borotropic shift, the related Ti(IV) complex {hydrido-[bis(3-Me,5-Me 2Bz)(3-Me 2Bz,5-Me)-pyrazol-1-yl]borato}trichlorotitanium(IV), [Tp Me2 Bz,Me∗∗] TiCl 3 ( 3). The 1H- and 13C NMR spectra of the new compounds are discussed, the molecular structure of 3 has been determined by X-ray diffraction methods, the titanium centre has a pseudo-octahedral coordination, with the nitrogen and chloride ligands in a fac geometry. A possible mechanism of formation of 3 is proposed.

Dimethylplatinum (II) complexes with isocyanocoumarin ligands: the crystal structure of cis-dimethylbis-(7-diethylamino-3-isocyanocoumarin)platinum(II)

Platinum complexes that contain isocyanocourmarin ligands have been prepared. [Pt 2Me 4( μ-SMe 2) 2] and [PtPh 2(SMe 2) 2] react with ligands L, (L = 7-diethylamino-3-isocyanocoumarin, Idc; 7-isocyano-4-methylcoumarin, Mic; 7-isocyano-4-trifluoromethylcoumarin, Tic; 3-chloro-4-methyl-7-isocyanocoumarin, Cmic), to give PtR 2L 2, monomers in high yield. The NMR and IR spectra of these complexes are consistent with cis stereochemistry. The UV–Vis absorption spectra of the complexes show bands assigned to ligand-centered transitions. Excitation into the absorption bands of the Idc complexes gives emission at room temperature in methylene chloride solution. The oxidative addition reaction of two of these complexes with methyl iodide has been studied. Platinum (IV) species with fac geometry have been isolated and characterized. Cis-dimethylbis-(7-diethylamino-3-isocyanocoumarin)platinum(II) was characterized by X-ray diffraction.

Metal complexes of the trans-influencing ligand thiomaltol.

The wide use of the ligand 3-hydroxy-2-methyl-4-pyrone (maltol) in bioinorganic chemistry has prompted an effort to further exploit this ligand class by achieving an efficient, one-step synthesis of the chelator 3-hydroxy-2-methyl-4-thiopyrone (thiomaltol). Complexes of thiomaltol with nickel(II) and iron(III) have been prepared and studied by using UV-visible spectroscopy and electrochemical methods. In addition, both complexes as well as the free thiomaltol ligand have been structurally characterized by using single-crystal X-ray diffraction methods. The ligand is found to exert a strong trans influence on the structure of the complexes in the solid state with the nickel(II) and iron(III) complexes demonstrating a cis and fac geometry, respectively. The compounds described here should significantly expand the scope and utility of O,S-donor ligands derived from maltol and related precursors.

Isomerization in substitution processes of cyclometallated dimethylhaloplatinum(iv) complexesElectronic supplementary information (ESI) available: kobs, the axMe signal intensity of 1, the 1H NMR spectrum of 3, and the temperature evolution of 1H NMR signals of SMe2 in isomers of 5. See http://www.rsc.org/suppdata/dt/b2/b209844j/

Cyclometallated imine platinum(IV) derivatives of general formula [PtX(Me)2(C–N)(SMe2)], being X = Br and Cl with C–N = CC5H4CH2NCH(2,4,6-Me3C6H2) (1 and 2); X = I with C–N = CC5H4CHNBzl (3); X = Br with C–N = CC5H4CHNPh and CC5H4CH2N(2,4,6-Me3C6H2) (4 and 5), and X = I with C–N = CC5H4CH2N(2,4,6-Me3C6H2) (6) have been characterised as having different fac(Me/Me/SMe2) to mer(Me/Me/SMe2) geometrical disposition ratios. The isomeric fac(Me/Me/SMe2) form is present at various percentages depending on the rigidity of the system, from a maximum of 100% for complexes 1 and 2 as proved from the X-ray crystal structure determination of both complexes and selective NOE experiments, to a minimum of 30% in the case of 3. SMe2 by PPh3 substitution has been studied for these fac complexes where, in comparison to similar compounds with a mer(Me/Me/SMe2) disposition, the strong trans-influence of the methyl group is avoided. The results indicate that there are more important effects than the simple trans-influence of the methyl ligand, the reactions are found to be much faster than their equivalent with complexes with mer geometries. In some of the cases, the final phosphine substituted products show the full isomerization to expected less hindered mer(Me/Me/PPh3) geometry, while in others, a mixture of the fac and mer arrangements is found in the final reaction products. For the 2,4,6Me3C6H2-containing imines the isomerization takes place during substitution from a postulated pentacoordinated intermediate, for the remaining complexes the final reaction mixture is obtained in a process that takes place after substitution. For these two cases (products 3 and 4), the presence of an intermediate with a fac(Me/Me/PPh3) geometry, that further evolves to the final mer complex, has been characterised by low temperature NMR, and the isomerization reactions have been studied as a function of temperature and pressure. The results agree with a process involving a very energetically demanding turnstile twist type reorganization of the molecule, after a significant degree of dissociation of the ligands (ΔH‡ = 109 and 100 kJ mol−1; ΔS‡ = 88 and 49 J K−1 mol−1; ΔV‡ = 14.9 and 20.0 cm3 mol−1 for compounds 3 and 4 respectively).

Hydrothermal preparation, structures, and NLO properties of the rare earth molybdenyl iodates, RE(MoO2)(IO3)4(OH) [RE = Nd, Sm, Eu

The reactions of RE(IO3)3 [RE = Nd, Sm, Eu] with I2O5 and MoO3 in a 1:2:2 molar ratio at 200 degrees C in aqueous media provide access to RE(MoO2)(IO3)4(OH) [RE = Nd (1), Sm (2), Eu (3)] as pure phases as determined from powder X-ray diffraction data. Single crystal X-ray diffraction experiments demonstrate that these compounds are isostructural and crystallize in the chiral and polar space group P2(1). The structures are composed of three-dimensional networks formed from eight-coordinate, square antiprismatic RE3+ cations and MoO2(OH)+ moieties that are bound by bridging iodate anions. The Mo(VI) centers are present in distorted octahedral environments composed of two cis-oxo atoms, a hydroxo group, and three bridging iodate anions arranged in a fac geometry. There are four crystallographically unique iodate anions in the structures of 1-3, one of these is actually present in the form of a IO3+1 polyhedron where a short interaction of 2.285(4) A is formed between the iodate anion and the hydroxo group bound to the Mo(VI) center. This interaction results in significant distortions of the iodate anion similar to those found in tellurites with TeO3+1 units. Two of the four iodate anions are aligned along the polar b-axis, imparting the required polarity to these compounds. Second-harmonic generation (SHG) measurements on sieved powders of 1 show a response of 350 x alpha-quartz. Crystallographic data: 1, monoclinic, space group P2(1), a = 6.9383(5) A, b = 14.0279(9) A, c = 7.0397(5) A, beta = 114.890(1) degrees, Z = 2; 2, monoclinic, space group P2(1), a = 6.9243(6) A, b = 13.963(1) A, c = 7.0229(6) A, beta = 114.681(1) degrees, Z = 2; 3, monoclinic, space group P2(1), a = 6.9169(6) A, b = 13.943(1) A, c = 7.0170(6) A, beta = 114.542(1) degrees, Z = 2.

Synthesis, spectroscopic and structural characterisation of complexes of the new ditelluroether 1,2-bis(methyltelluromethyl)benzene, o-C 6H 4(CH 2TeMe) 2. X-ray structures of [Mn(CO) 3Cl{ o-C 6H 4(CH 2TeMe) 2}] and [W(CO) 4{ o-C 6H 4(CH 2TeMe) 2}

The synthesis of the new xylyl-backboned ditelluroether, 1,2-bis(methyltelluromethyl)benzene, o-C 6H 4(CH 2TeMe) 2 (xyte) is described. A range of complexes — [Mn(CO) 3Cl(xyte)], [M(CO) 4(xyte)] (M=Mo or W), [M′Cl 2(xyte)], [M′(xyte) 2][PF 6] 2 (M′=Pd or Pt), trans-[RuCl 2(xyte) 2], trans-[OsCl 2(xyte) 2], [Cu(xyte) 2]PF 6 and [Ag(xyte) 2]CF 3SO 3, have been prepared and characterised by analysis, IR, UV–visible, and multinuclear NMR spectroscopy. The crystal structure of [Mn(CO) 3Cl(xyte)] shows the expected fac geometry with a meso-2 xyte ligand conformation, and the meso-conformation is also found in [W(CO) 4(xyte)]. The xyte complexes provide the first detailed studies of a 7-membered ring ditelluroether chelate, and the properties are compared with those of MeTe(CH 2) 3TeMe or o-C 6H 4(TeMe) 2 to explore the effects of chelate ring size.

Oxygen atom transfer from nitrogenous ReVO reagents to diphosphines and subsequent transformations. Rhenium(III) products and reaction models.

The concerned diphosphines are Ph2P(CH2)nPPh2 (1), abbreviated PnP, and the ReVO reagents are ReOCl3L (2) and ReOCl3L' (3), where L and L' are the azopyridine and pyridine-imine ligands p-ClC6H4N=NC5H4N and p-MeC6H4N=CHC5H4N, respectively. One atom transfer from 2 to 1 has afforded Re(OPnP)Cl3L (4a, n = 1; 4b, n = 2; 4c, n = 3). Of these 4b and 4c are stable, but 4a undergoes spontaneous isomerization to Re(PlPO)Cl3L (5) in solution. Two-atom transfer studied with both 2 and 3 has afforded binuclear LCl3Re(OPnPO)ReCl3L (8a, n = 2; 8b, n = 3) and L'Cl3Re(OPnPO)ReCl3L' (9a, n = 2; 9b, n = 3) for n = 2, 3 and mononuclear Re(OP1PO)Cl3L (11) and Re(OP1PO)Cl3L' (12) for n = 1. The mixed system L'Cl3Re(OP2PO)ReCl3L (10) has been prepared from 3 and 4b. The complex Re(PPh3)Cl3L (7a) is furnished by the reaction of Re(OPPh3)Cl3L (6a) or 4b or 11 with PPh3. The species have been characterized with the help of spectral, electrochemical, and X-ray structural data. All the complexes have mer geometry except 5 and 7a, which have fac geometry. The latter is best suited for concurrent Re-N and Re-P back-bonding. Variable-temperature rate data of the reaction 4a-->5 are consistent with an intramolecular strongly associative transition state (delta S++, -22.6 eu) in which the dangling phosphine function lies close to the metal. Two-atom transfer to P1P is believed to proceed via a transient binuclear intermediate which undergoes cleavage at one end due to steric crowding, affording 11 and 12. Crystal data for the complexes are as follows: 5.1.5 C6H6, empirical formula C45H39Cl4N3OP2Re, crystal system triclinic, space group P1, a = 10.034(2) A, b = 10.737(2) A, c = 20.357(4) A, alpha = 89.38(3) degrees, beta = 87.79(3) degrees, gamma = 80.22(3) degrees, V = 2159.7(7) A3, Z = 2; 7a.CH2Cl2, empirical formula C30H25Cl6N3PRe, crystal system monoclinic, space group P2(1)/n, a = 11.695(6) A, b = 17.745(7) A, c = 15.459(9) A, beta = 100.94(5) degrees, V = 3150(3) A3, Z = 4; 9a, empirical formula C52H48Cl6N4O2P2Re2, crystal system monoclinic, space group C2/c, a = 19.769(12) A, b = 12.864(6) A, c = 22.20(2) A, beta = 101.76(6) degrees, V = 5530(6) A3, Z = 4; 11, empirical formula C36H30Cl4N3O2P2Re, crystal system monoclinic, space group I2/a, a = 16.866(6) A, b = 12.583(6) A, c = 34.78(2) A, beta = 99.22(4) degrees, V = 7285(7) A3, Z = 8.

Ruthenium Complexes with Novel Tridentate N,P,N Ligands Containing a Phosphonite Bridge between Two Chiral Oxazolines. Catalytic Activity in Cyclopropanation of Olefins and Transfer Hydrogenation of Acetophenone

We compare the coordination behavior of the new chiral ligand (S,S)-bis[1-(4-isopropyl-4,5-dihydrooxazol-2-yl)-1-methylethyl] phenylphosphonite (V), abreviated NOPONiPr and referred to as bis(oxazolinyl) phenylphosphonite, toward Ru(II) with that of NOPONMe2 (IV). Although the similarity between IV and V led to the expectation that they would coordinate in a similar manner, considerable differences were observed. Whereas reaction of [RuCl2(η6-p-cymene)]2 with IV afforded the pentacoordinated complex [RuCl2(NOPONMe2)] 1, the chiral ligand V led instead to the dinuclear, chloride-bridged complex [Ru(μ-Cl)Cl(NOPONiPr)]2 (3). The crystal structures of 1 and 3 have been determined by X-ray diffraction. The mer arrangement of the NOPONMe2 ligand in 1 results from the presence of the four methyl groups, two of which would point toward each other and lead to a steric clash if a fac geometry were adopted. Preliminary theoretical calculations on 1 at the EHT level indicated that coordination of ethylene parallel to...

Structures of bis-ethylmaltolatodichloro-tin(IV) and -titanium(IV) and of trichloro(1-methyl-2-ethyl-3-hydroxy-4 H-pyridin-4-onato)aquatin(IV)

The structures of solvates of the bis-ethylmaltolatodichloro-metal(IV) complexes M(etma) 2Cl 2, with M=Sn and Ti, and of trichloro(1-methyl-2-ethyl-3-hydroxy-4 H-pyridin-4-onato)aquatin(IV), Sn(mepp)Cl 3(H 2O), have been established by single crystal X-ray diffraction methods. Sn(etma) 2Cl 2 crystallised with one molecule of dichloromethane, Ti(etma) 2Cl 2 with one molecule of tetrahydrofuran, and Sn(mepp)Cl 3(H 2O) with one molecule of acetone, from their respective recrystallisation media. Both ethylmaltol complexes M(etma) 2Cl 2 are cis-octahedral. The coordination around the tin atom in Sn(mepp)Cl 3(H 2O) approximates to octahedral, with the three chloride ligands in fac geometry. The tin(IV)–water bond distance in this pyridinone complex is discussed in relation to this distance in other aquatin(IV) complexes. The effects of coordinating tin(IV) on the geometry of the coordinated pyridinone are considered.

ReCl3(C8H11P)2(C7H11N)2].C6H4Cl2

Trichlorobis(cyclohexyl isocyanide)bis(dimethylphenylphosphine)rhenium(III) has been synthesized from [ReOCl 3 (CNCy) 2 ] (Cy = cyclohexyl) by the removal of oxygen with excess dimethylphenylphosphine. The structure of its 1,2-dichlorobenzene adduct, determined by single-crystal X-ray methods, has a monocapped octahedral arrangement (idealized C s symmetry) of the seven ligands about the Re atom; the three Cl atoms adopt a fac geometry, opposite the face capped by one isocyanide ligand

Transition metal compounds of the tridentate pyrazole substituted amine ligand bis(2-(3,5-dimethyl-1-pyrazolyl)ethyl)ethylamine (ddae). X-ray structures of [Co(ddae)(NO 3) 2], [Cu(ddae)(NO 3)(H 2O)](NO 3) and [Cu(ddae)(Cl) 2]·C 2H 5OH

Six new compounds of the ligand bis(2-(3,5-dimethyl-1-pyrazolyl)ethyl)ethylamine (ddae), viz. [Co(ddae)(NO 3) 2], [Ni(ddae)(NO 3) 2], [Cu(ddae)(Cl) 2]·(C 2H 5OH), [Cu(ddae)(NO 3)(H 2O)](NO 3), [Ni(ddae)(H 2O)(BF 4) 2] and [Cu(ddae)(F)(BF 4)] are described. These transition metal compounds are mononuclear. In all cases ddae acts as a tridentate ligand. The cobalt and nickel nitrates are isomorphous, otherwise these compounds all have different structures. The compound [Cu(ddae)Cl 2]·C 2H 5OH crystallizes in the monoclinic space group P2 1/ c with a=8.327(1), b=14.782(2), c=18.654(3) Å, β=96.53(1)° and Z=4. The structure was solved by heavy-atom methods and refined by least-squares methods to a residual R of 0.048 ( R w=0.081) for 2787 significant reflections. The asymmetric unit comprises the whole formula unit. The surrounding geometry of the Cu(II) ion is distorted square-pyramidal with the two pyrazole nitrogens (CuN distances 1.984(4) and 1.999(4) Å) and the two chloride ions (CuCl distances 2.322(2) and 2.400(2) Å) in a square and the amine nitrogen (CuN distance 2.181(4) Å) at the apex. The ligand is coordinated in a mer geometry. The ethanol molecule is hydrogen bonded to one of the chloride ions with a ClO distance of 3.24(1) Å. The compound [Cu(ddae)(NO 3)(H 2O)](NO 3) crystallizes in the orthorhombic space group Pna2 1 with a=24.984(5), b=10.798(2), c=8.466(3) Å and Z=4. The structure was solved by heavy-atom methods and refined by least-squares methods to a residual R of 0.048 ( R w=0.069) for 960 significant reflections. The asymmetric unit comprises the whole formula unit. The Cu(II) ion is in a distorted square-pyramidal environment of the two pyrazole nitrogens at 2.00(1) and 2.01(1) Å, a water oxygen atom at 1.938(9) Å, and an oxygen atom of one of the nitrate ions at 2.00(1) Å in a square, and the amine nitrogen at 2.34(1) Å at the apex. The ligand is folded and coordinated in a fac geometry. If the nitrate ion was regarded as bidentate-coordinate with the rather too long CuO distance of 2.63(1) Å, then the copper ion would be in a strongly distorted octahedral environment. The water molecule is hydrogen bonded to the non- coordinated nitrate ion in two different, symmetry related, positions, with OO distances of 2.74(1) and 2.81(2) Å, in such a way that the complex cations are linked together in a chain. The compound [Co(ddae)(NO 3) 2] crystallizes in the monoclinic space group P2 1/ c with a=16.351(3), b=15.708(2), c=8.484(1) Å, β=104.78(1)° and Z=4. The structure was solved by heavy-atom methods and refined by least-squares methods to a residual R of 0.077 ( R w=0.065) for 1502 significant reflections. The asymmetric unit comprises the whole formula unit. The surrounding geometry of the Co(II) ion is distorted octahedral, with the ligand folded in a fac geometry with the N(amine) at 2.209(9) Å and the N(pyrazoles) at 2.030(10) and 2.112(9) Å. One of the nitrate ions is monodentate with CoO of 2.060(8), the other nitrate is quite symmetrically bidentate coordinated to the cobalt ion with CoO distances of 2.172(8) and 2.216(8) Å.

Complexes of functionalised phosphine ligands. Part 1. Complexes of FeIII, CoIII, NiIIand ReVwith tridentate Schiff bases having PNO, NNO and NNS donor sets. Crystal structures of 2-(Ph2PC6H4NCH)C6H4OH and [Co{2-(Ph2PC6H4CHN)C6H4O}2][PF6

The Schiff bases 2-[Ph2P(CH2)nNCH]C6H4OH (n= 3, HL1 or 2 HL2), 2-(RCHN)C6H3(OH)X-4 (R = 2-Ph2PC6H4, X = H HL3; R = 2-C5H4N, X = H HL4; R = 2-C5H4N, X = Cl HL5) were synthesised from the appropriate amine and aldehyde. On deprotonation these all functioned as tridentate monoanionic ligands to give complexes [FeL2]+ and [CoL2]+ with FeIII and CoIII and neutral complexes of stoichiometry NiL2 with NiII. The iron complexes were examined by Mossbauer spectroscopy which indicated the presence of two iron sites in [FeL12]+ with a spin-state equilibrium dependent on both temperature and the counter ion. The complex [FeL32]+ showed a single iron site, again with a spin state dependent on counter ion and temperature. The crystal structures of HL3 and [CoL32]+ have been determined. The distortions in free HL3 predispose it for co-ordination in a fac geometry to the Co with cis-PPh2 groups, and the changes occurring on co-ordination are discussed in detail. Reaction of RCHO (R = 2-Ph2PC6H4 or 2-C5H4N) with 2-aminobenzenethiol gave stable thiazoles R[graphic omitted]-2 which did not ring open to give tridentate ligands even on reaction with base and/or metal ions.