Synthesis, structures, and reactivity of weakly coordinating anions with delocalized borate structure: the assessment of anion effects in metallocene polymerization catalysts.

The formation of adducts of tris(pentafluorophenyl)borane with strongly coordinating anions such as CN(-) and [M(CN)(4)](2)(-) (M = Ni, Pd) is a synthetically facile route to the bulky, very weakly coordinating anions [CN[B(C(6)F(5))(3)](2)](-) and [M[CNB(C(6)F(5))(3)](4)](2-) which are isolated as stable NHMe(2)Ph(+) and CPh(3)(+) salts. The crystal structures of [CPh(3)][CN[B(C(6)F(5))(3)](2)] (1), [CPh(3)][ClB(C(6)F(5))(3)] (2), [NHMe(2)Ph](2)[Ni[CNB(C(6)F(5))(3)](4)].2Me(2)CO (4b.2Me(2)CO), [CPh(3)](2)[Ni[CNB(C(6)F(5))(3)](4)].2CH(2)Cl(2) (4c.2CH(2)Cl(2)), and [CPh(3)](2)[Pd[CNB(C(6)F(5))(3)](4)].2CH(2)Cl(2) (5c.2CH(2)Cl(2)) are reported. The CN stretching frequencies in 4 and 5 are shifted by approximately 110 cm(-1) to higher wavenumbers compared to the parent tetracyano complexes in aqueous solution, although the M-C and C-N distances show no significant change on B(C(6)F(5))(3) coordination. Zirconocene dimethyl complexes L(2)ZrMe(2) [L(2) = Cp(2), SBI = rac-Me(2)Si(Ind)(2)] react with 1, 4c or 5c in benzene solution at 20 degrees C to give the salts of binuclear methyl-bridged cations, [(L(2)ZrMe)(2)(mu-Me)][CN[B(C(6)F(5))(3)](2)] and [(L(2)ZrMe)(2)(mu-Me)](2)[M[CNB(C(6)F(5))(3)](4)]. The reactivity of these species in solution was studied in comparison with the known [[(SBI)ZrMe](2)(mu-Me)][B(C(6)F(5))(4)]. While the latter reacts with excess [CPh(3)][B(C(6)F(5))(4)] in benzene to give the mononuclear ion pair [(SBI)ZrMe(+).B(C(6)F(5))(4)(-)] in a pseudo-first-order reaction, k = 3 x 10(-4) s(-1), [(L(2)ZrMe)(2)(mu-Me)][CN[B(C(6)F(5))(3)](2)] reacts to give a mixture of L(2)ZrMe(mu-Me)B(C(6)F(5))(3) and L(2)ZrMe(mu-NC)B(C(6)F(5))(3). Recrystallization of [Cp' '(2)Zr(mu-Me)(2)AlMe(2)][CN[B(C(6)F(5))(3)](2)] affords Cp' '(2)ZrMe(mu-NC)B(C(6)F(5))(3) 6, the X-ray structure of which is reported. The stability of [(L(2)ZrMe)(2)(mu-Me)](+)X(-) decreases in the order X = [B(C(6)F(5))(4)] > [M[CNB(C(6)F(5))(3)](4)] > [CN[B(C(6)F(5))(3)](2)] and increases strongly with the steric bulk of L(2) = Cp(2) < SBI. Activation of (SBI)ZrMe(2) by 1 in the presence of AlBu(i)(3) gives extremely active ethene polymerization catalysts. Polymerization studies at 1-7 bar monomer pressure suggest that these, and by implication most other highly active ethene polymerization catalysts, are strongly mass-transport limited. By contrast, monitoring propene polymerization activities with the systems (SBI)ZrMe(2)/1/AlBu(i)(3) and CGCTiMe(2)/1/AlBu(i)(3) at 20 degrees C as a function of catalyst concentration demonstrates that in these cases mass-transport limitation is absent up to [metal] approximately 2 x 10(-5) mol L(-1). Propene polymerization activities decrease in the order [CN[B(C(6)F(5))(3)](2)](-) > [B(C(6)F(5))(4)](-) > [M[CNB(C(6)F(5))(3)](4)](2-) > [MeB(C(6)F(5))(3)](-), with differences in activation barriers relative to [CN[B(C(6)F(5))(3)](2)](-) of DeltaDeltaG = 1.1 (B(C(6)F(5))(4)(-)), 4.1 (Ni[CNB(C(6)F(5))(3)](4)(2-)) and 10.7-12.8 kJ mol(-)(1) (MeB(C(6)F(5))(3)(-)). The data suggest that even in the case of very bulky anions with delocalized negative charge the displacement of the anion by the monomer must be involved in the rate-limiting step.     

Mononuclear and mixed-valence binuclear oxovanadium complexes with benzimidazole-derived chelating agents

Oxovanadium complexes with H(2)bzimpy (2,6-bis[benzimidazol-2'-yl]pyridine) and Me(2)bzimpy (2,6-bis[N'-methylbenzimidazol-2'-yl]pyridine), and H(3)ntb (tris[benzimidazol-2'-yl-methyl]amine) and Me(3)ntb (tris[N'-methylbenzimidazol-2'-yl-methyl]amine) have been synthesized. Dioxovanadium(V) and oxovanadium(IV) complexes prepared from H(2)bzimpy and Me(2)bzimpy are [V(V)O(2)(Hbzimpy)].1.25H(2)O (1), [V(V)O(2)(Me(2)bzimpy)](ClO(4)).H(2)O (3), [V(IV)O(H(2)bzimpy)(H(2)O)(2)](CF(3)SO(3))(2).2H(2)O (2), and [V(IV)O(Me(2)bzimpy)(H(2)O)(2)](CF(3)SO(3))(2) (4). H(3)ntb and Me(3)ntb afforded oxovanadium(IV) complexes, [V(IV)O(Hntb)].2MeOH (5), [V(IV)O(H(3)ntb)Cl]Cl.H(2)O (7), [V(IV)O(Me(3)ntb)SO(4)].H(2)O (9), [V(IV)O(Me(3)ntb)Cl]Cl.H(2)O (10), and mixed-valence complexes, [(H(3)ntb)V(IV)O(mu-O)V(V)O(H(3)ntb)](CF(3)SO(3))(3).2H(2)O (8) and [(Me(3)ntb)V(IV)O(mu-O)V(V)O(Me(3)ntb)](CF(3)SO(3))(3).3H(2)O (11). Crystal structures of 2, 7, and 11 are reported. The mixed-valence complexes, 8 and 11, show 15-line isotropic ESR spectra in fluid solutions at room temperature. These compounds also exhibit an intervalence transfer band around 1015 nm which is essentially independent of solvent, so these compounds are stable, mixed-valence species where the single unpaired electron is delocalized over the two vanadium centers at ambient temperature. With respect to one-electron reduction, the dioxovanadium(V) complexes are redox-potential equivalent with their monooxovanadium(IV) counterparts.     

Synthesis, characterization, crystal structure and preliminary reactivity behaviour of new heteropolytopic ligands based on the 1,3,5-triazine spacer and pyrazolyl, tris-pyrazolylmethyl and tris-pyrazolylethoxy bonding fragments

Four new potentially polytopic nitrogen donor ligands based on the 1,3,5-triazine fragment, L(1)-L(4) (L(1) = 2-chloro-4,6-di(1H-pyrazol-1-yl)-1,3,5-triazine, L(2) = N,N'-bis(4,6-di(1H-pyrazol-1-yl)-1,3,5-triazin-2-yl)ethane-1,2-diamine, L(3) = 2,4,6-tris(tri(1H-pyrazol-1-yl)methyl)-1,3,5-triazine, and L(4) = 2,4,6-tris(2,2,2-tri(1H-pyrazol-1-yl)ethoxy)-1,3,5-triazine) have been synthesized and characterized. The X-ray crystal structure of L(3) confirms that its molecular nature consists of a 1,3,5-triazine ring bearing three tripodal tris(pyrazolyl) arms. L(1), L(2), and L(4) react with Cu(I), Cu(II), Pd(II) and Ag(I) salts yielding mono-, di-, and oligonuclear derivatives: [Cu(L(1))(Cy(3)P)]ClO(4), [{Ag(2)(L(2))}(CF(3)SO(3))(2)]·H(2)O, [Cu(2)(L(2))(NO(3))(2)](NO(3))(2)·H(2)O, [Cu(2)(L(2))(CH(3)COO)(2)](CH(3)COO)(2)·3H(2)O, [Pd(2)(L(2))(Cl)(4)]·2H(2)O, [Ru(L(2))(Cl)(OH)]·CH(3)OH, [Ag(3)(L(4))(2)](CF(3)SO(3))(3) and [Ag(3)(L(4))(2)](BF(4))(3). The interaction of L(3) with Ag(I), Cu(II), Zn(II) and Ru(II) complexes unexpectedly produced the hydrolysis of the ligand with formation, in all cases, of tris(pyrazolyl)methane (TPM) derivatives. In detail, the already known [Ag(TPM)(2)](CF(3)SO(3)) and [Cu(TPM)(2)](NO(3))(2), as well as the new [Zn(TPM)(2)](CF(3)SO(3))(2) and [Ru(TMP)(p-cymene)]Cl(OH)·2H(2)O complexes have been isolated. Single-crystal XRD determinations on the latter derivatives confirm their formulation, evidencing, for the Ru(II) complex, an interesting supramolecular arrangement of the anions and crystallization water molecules.     

Anion binding by metallo-receptors of 5,5'-dicarbamate-2,2'-bipyridine ligands

Three 5,5'-dicarbamate-2,2'-bipyridine ligands (L = L(1)-L(3)) bearing ethyl, isopropyl or tert-butyl terminals, respectively, on the carbamate substituents were synthesized. Reaction of the ligands L with the transition metal ions M = Fe(2+), Cu(2+), Zn(2+) or Ru(2+) gave the complexes ML(n)X(2)·xG (1-12, n = 1-3; X = Cl, NO(3), ClO(4), BF(4), PF(6), ?SO(4); G = Et(2)O, DMSO, CH(3)OH, H(2)O), of which [Fe(L(2))(3)???SO(4)]·8.5H(2)O (2), [Fe(L(1))(3)???(BF(4))(2)]·2CH(3)OH (7), [Fe(L(2))(3)???(Et(2)O)(2)](BF(4))(2)·2CH(3)OH (8), [ZnCl(2)(L(1))][ZnCl(2)(L(1))(DMSO)]·2DMSO (9), [Zn(L(1))(3)???(NO(3))(2)]·2H(2)O (10), [Zn(L(2))(3)???(ClO(4))(Et(2)O)]ClO(4)·Et(2)O·2CH(3)OH·1.5H(2)O (11), and [Cu(L(1))(2)(DMSO)](ClO(4))(2)·2DMSO (12) were elucidated by single-crystal X-ray crystallography. In the complexes ML(n)X(2)·xG the metal ion is coordinated by n = 1, 2 or 3 chelating bipyridine moieties (with other anionic or solvent ligands for n = 1 and 2) depending on the transition metal and reaction conditions. Interestingly, the carbamate functionalities are involved in hydrogen bonding with various guests (anions or solvents), especially in the tris(chelate) complexes which feature the well-organized C(3)-clefts for effective guest inclusion. Moreover, the anion binding behavior of the pre-organized tris(chelate) complexes was investigated in solution by fluorescence titration using the emissive [RuL(3)](2+) moiety as a probe. The results show that fluorescent recognition of anion in solution can be achieved by the Ru(II) complexes which exhibit good selectivities for SO(4)(2-).     

Heterolytic cleavage of dihydrogen promoted by sulfido-bridged tungsten-ruthenium dinuclear complexes

A series of sulfido-bridged tungsten-ruthenium dinuclear complexes Cp*W(mu-S)(3)RuX(PPh(3))(2) (4a; X = Cl, 4b; X = H), Cp*W(O)(mu-S)(2)RuX(PPh(3))(2) (5a; X = Cl, 5b; X = H), and Cp*W(NPh)(mu-S)(2)RuX(PPh(3))(2) (6a; X = Cl, 6b; X = H) have been synthesized by the reactions of (PPh(4))[Cp*W(S)(3)] (1), (PPh(4))[Cp*W(O)(S)(2)] (2), and (PPh(4))[Cp*W(NPh)(S)(2)] (3), with RuClX(PPh(3))(3) (X = Cl, H). The heterolytic cleavage of H(2) was found to proceed at room temperature upon treating 5a and 6a with NaBAr(F)(4) (Ar(F) = 3, 5-C(6)H(3)(CF(3))(2)) under atmospheric pressure of H(2), which gave rise to [Cp*W(OH)(mu-S)(2)RuH(PPh(3))(2)](BAr(F)(4)) (7a) and [Cp*W(NHPh)(mu-S)(2)RuH(PPh(3))(2)](BAr(F)(4)) (8), respectively. When Cp*W(O)(mu-S)(2)Ru(PPh(3))(2)H (5b) was treated with a Br?nstead acid, [H(OEt(2))(2)](BAr(F)(4)) or HOTf, protonation occurred exclusively at the terminal oxide to give [Cp*W(OH)(mu-S)(2)RuH(PPh(3))(2)](X) (7a; X = BAr(F)(4), 7b; X = OTf), while the hydride remained intact. The analogous reaction of Cp+W(mu-S)(3)Ru(PPh(3))(2)H (4b) led to immediate evolution of H(2). Selective deprotonation of the hydroxyl group of 7a or 7b was induced by NEt(3) and 4b, generating Cp*W(O)(mu-S)(2)Ru(PPh(3))(2)H (5b). Evolution of H(2) was also observed for the reactions of 7a or 7b with CH(3)CN to give [Cp*W(O)(mu-S)(2)Ru(CH(3)CN)(PPh(3))(2)](X) (11a; X = BAr(F)(4), 11b; X = OTf). We examined the H/D exchange reactions of 4b, 5b, and 7a with D(2) and CH(3)OD, and found that facile H/D scrambling over the W-OH and Ru-H sites occurred for 7a. Based on these experimental results, the mechanism of the heterolytic H(2) activation and the reverse H(2) evolution reactions are discussed.     

Symmetric and asymmetric dinuclear manganese(IV) complexes possessing a [MnIV2(mu-O)2(muO2CMe)]3+ core and terminal Cl- ligands

The synthesis of new dinuclear manganese(IV) complexes possessing the [Mn(IV)(2)(mu-O)(2)(mu-O(2)CMe)](3+) core and containing halide ions as terminal ligands is reported. [Mn(2)O(2)(O(2)CMe)Cl(2)(bpy)(2)](2)[MnCl(4)] (1; bpy = 2,2'-bipyridine) was prepared by sequential addition of [MnCl(3)(bpy)(H(2)O)] and (NBzEt(3))(2)[MnCl(4)] to a CH(2)Cl(2) solution of [Mn(3)O(4)(O(2)CMe)(4)(bpy)(2)]. The complex [Mn(IV)(2)O(2)(O(2)CMe)Cl(bpy)(2)(H(2)O)](NO(3))(2) (2) was obtained from a water/acetic acid solution of MnCl(2).4H(2)O, bpy, and (NH(4))(2)[Ce(NO(3))(6)], whereas the [Mn(IV)(2)O(2)(O(2)CR)X(bpy)(2)(H(2)O)](ClO(4))(2) [X = Cl(-) and R = Me (3), Et (5), or C(2)H(4)Cl (6); and X = F(-), R = Me (4)] were prepared by a slightly modified procedure that includes the addition of HClO(4). For the preparation of 4, MnF(2) was employed instead of MnCl(2).4H(2)O. [Mn(2)O(2)(O(2)CMe)Cl(2)(bpy)(2)](2)[MnCl(4)].2CH(2)Cl(2) (1.2CH(2)Cl(2)) crystallizes in the monoclinic space group C2/c with a = 21.756(2) A, b = 12.0587(7) A, c = 26.192(2) A, alpha = 90 degrees, beta = 111.443(2) degrees, gamma = 90 degrees, V = 6395.8(6) A(3), and Z = 4. [Mn(2)O(2)(O(2)CMe)Cl(H(2)O)(bpy)(2)](NO(3))(2).H(2)O (2.H(2)O) crystallizes in the triclinic space group Ponemacr; with a = 11.907(2) A, b = 12.376(2) A, c = 10.986(2) A, alpha = 108.24(1) degrees, beta = 105.85(2) degrees, gamma = 106.57(1) degrees, V = 1351.98(2) A(3), and Z = 2. [Mn(2)O(2)(O(2)CMe)Cl(H(2)O)(bpy)(2)](ClO(4))(2).MeCN (3.MeCN) crystallizes in the triclinic space group Ponemacr; with a = 11.7817(7) A, b = 12.2400(7) A, c = 13.1672(7) A, alpha = 65.537(2) degrees, beta = 67.407(2) degrees, gamma = 88.638(2) degrees, V = 1574.9(2) A(3), and Z = 2. The cyclic voltammogram (CV) of 1 exhibits two processes, an irreversible oxidation of the [MnCl(4)](2)(-) at E(1/2) approximately 0.69 V vs ferrocene and a reversible reduction at E(1/2) = 0.30 V assigned to the [Mn(2)O(2)(O(2)CMe)Cl(2)(bpy)(2)](+/0) couple (2Mn(IV) to Mn(IV)Mn(III)). In contrast, the CVs of 2 and 3 show only irreversible reduction features. Solid-state magnetic susceptibility (chi(M)) data were collected for complexes 1.1.5H(2)O, 2.H(2)O, and 3.H(2)O in the temperature range 2.00-300 K. The resulting data were fit to the theoretical chi(M)T vs T expression for a Mn(IV)(2) complex derived by use of the isotropic Heisenberg spin Hamiltonian (H = -2JS(1)S(2)) and the Van Vleck equation. The obtained fit parameters were (in the format J/g) -45.0(4) cm(-)(1)/2.00(2), -36.6(4) cm(-)(1)/1.97(1), and -39.3(4) cm(-)(1)/1.92(1), respectively, where J is the exchange interaction parameter between the two Mn(IV) ions. Thus, all three complexes are antiferromagnetically coupled.     

A hemilabile binucleating pincer ligand for self-assembly of coordination oligomers and polymers

The bis(PNP)-donor pincer ligand 1,4-C(6)H(4){N(CH(2)CH(2)PPh(2))(2)}(2), 1, contains weakly basic nitrogen donor atoms because the lone pairs of electrons are conjugated to the bridging phenylene group, and this feature is used in the synthesis of oligomers and polymers. The complexes [Pd(2)X(2)(mu-1)](OTf)(2), X=Cl, Br or OTf, contain the ligand 1 in bis(pincer) binding mode (mu-kappa(6)-P(4)N(2)), but [Pd(4)Cl(6)(mu(3-)1)(2)]Cl(2) contains the ligand in an unusual unsymmetrical mu(3)-kappa(5)-P(4)N binding mode. The bromide complex is suggested to exist as a polymer [{Pd(2)Br(4)(mu(4)-1)}(n)] with the ligands 1 in mu(4)-kappa(4)-P(4) binding mode. The methylplatinum(II) complexes [Pt(2)Me(4)(mu-1)] and [Pt(2)Me(2)(mu-1)](O(2)CCF(3))(2) contain the ligand in mu-kappa(4)-P(4) and mu-kappa(6)-P(4)N(2) bonding modes, while the silver(I) complex [Ag(2)(O(2)CCF(3))(2) (mu-1)] contains the ligand 1 in an intermediate bonding mode in which the nitrogen donors are very weakly coordinated. The complexes [Pd(2)(OTf)(2)(mu-1)](OTf)(2) and [Ag(2)(O(2)CCF(3))(2)(mu-1)] react with 4,4'-bipyridine to give polymers [Pd(2)(micro-bipy)(mu-1)](OTf)(4) and [Ag(2)(mu-bipy)(mu-1)](O(2)CCF(3))(2).     

Luminescent alkynyl platinum-cadmium complexes: structural characterization of an unusual decanuclear cluster

The reaction of (NBu(4))(2)[Pt(C triple bond CPh)(4)] with Cd(ClO(4))(2).6H(2)O in a 1:1 molar ratio yields a white solid [PtCd(C triple bond CPh)(4)](n) 1 (75% yield) together with yellow crystals of a very unusual decanuclear platinum-cadmium cluster [Pt(4)Cd(6)(C triple bond CPh)(4)(mu-C triple bond CPh)(12)(mu(3)-OH)(4)] 2 in low yield. Slow diffusion of acetonic solutions of the starting materials under aerobic conditions only produces crystals of 2 which have been shown by an X-ray analysis to be composed of a big hexanuclear cation [Cd(6)(mu(3)-OH)(4)](8+) and four [Pt(C triple bond CPh)(4)](2-) anions, held together by Pt.Cd and pi.Cd acetylide interactions. On the other hand, treatment of the insoluble product 1 with 1 equiv of NBu(4)X yields tetranuclear mixed-metal soluble complexes (NBu(4))(2)[[Pt(mu-C triple bond CPh)(4)](2)(CdX)(2)] (X = Cl A, Br 3, CN 4), which contain two platinate fragments connected by two CdX units through Pt.Cd and mainly Cd.C(alpha) interactions. All complexes are strongly emissive in the solid state at room temperature.     

Trapping unstable terminal M-O multiple bonds of monocyclopentadienyl niobium and tantalum complexes with Lewis acids

Hydrolysis of [NbCp'Cl(4)] (Cp' = η(5)-C(5)H(4)SiMe(3)) with the water adduct H(2)O·B(C(6)F(5))(3) afforded the oxo-borane compound [NbCp'Cl(2){O·B(C(6)F(5))(3)}] (2a). This compound reacted with [MgBz(2)(THF)(2)] giving [NbCp'Bz(2){O·B(C(6)F(5))(3)}] (2b), whereas [NbCp'Me(2){O·B(C(6)F(5))(3)}] (2c) was obtained from the reaction of [NbCp'Me(4)] with H(2)O·B(C(6)F(5))(3). Addition of Al(C(6)F(5))(3) to solutions containing the oxo-borane compounds [MCp(R)X(2){O·B(C(6)F(5))(3)}] (M = Ta, Cp(R) = η(5)-C(5)Me(5) (Cp*), X = Cl 1a, Bz 1b, Me 1c; M = Nb, Cp(R) = Cp', X = Cl 2a) afforded the oxo-alane complexes [MCp(R)X(2){O·Al(C(6)F(5))(3)}] (M = Ta, Cp(R) = Cp*, X = Cl 3a, Bz 3b, Me 3c; M = Nb, Cp(R) = Cp', X = Cl 4a), releasing B(C(6)F(5))(3). Compound 3a was also obtained by addition of Al(C(6)F(5))(3) to the dinuclear μ-oxo compound [TaCp*Cl(2)(μ-O)](2), meanwhile addition of the water adduct H(2)O·Al(C(6)F(5))(3) to [TaCp*Me(4)] gave complex 3c. The structure of 2a and 3a was obtained by X-ray diffraction studies. Density functional theory (DFT) calculations were carried out to further understand these types of oxo compounds.     

Macrocyclic copper(II) and zinc(II) complexes incorporating phosphate esters

Slow evaporation of solutions prepared by adding either Cu(ClO(4))(2).6H(2)O or Zn(ClO(4))(2).6H(2)O to solutions containing appropriate proportions of Me(3)tacn (1,4,7-trimethyl-1,4,7-triazacyclononane) and sodium phenyl phosphate (Na(2)PhOPO(3)) gave dark blue crystals of [Cu(3)(Me(3)tacn)(3)(PhOPO(3))(2)](ClO(4))(2).(1)/(2)H(2)O (1) and colorless crystals of [Zn(2)(Me(3)tacn)(2)(H(2)O)(4)(PhOPO(3))](ClO(4))(2).H(2)O (2), respectively. Blue crystals of [Cu(tacn)(2)](BNPP)(2) (3) formed in an aqueous solution of [Cu(tacn)Cl(2)], bis(p-nitrophenyl phosphate) (BNPP), and HEPES buffer (pH 7.4). Compound 1 crystallizes in the triclinic space group P1 (No. 2) with a = 9.8053(2) A, b = 12.9068(2) A, c = 22.1132(2) A, alpha = 98.636(1) degrees, beta = 99.546(1) degrees, gamma = 101.1733(8) degrees, and Z = 2 and exhibits trinuclear Cu(II) clusters in which square pyramidal metal centers are capped by two phosphate esters located above and below the plane of the metal centers. The trinuclear cluster is asymmetric having Cu...Cu distances of 4.14, 4.55, and 5.04 A. Compound 2 crystallizes in the monoclinic space group P2(1)/c (No. 14) with a = 13.6248(2) A, b = 11.6002(2) A, c = 25.9681(4) A, beta = 102.0072(9) degrees, and Z = 4 and contains a dinuclear Zn(II) complex formed by linking two units of [Zn(Me(3)tacn)(OH(2))(2)](2+) by a single phosphate ester. Compound 3 crystallizes in the monoclinic space group C2/c (No. 15) with a = 24.7105(5) A, b = 12.8627(3) A, c = 14.0079(3) A, beta = 106.600(1) degrees, and Z = 4 and consists of mononuclear [Cu(tacn)(2)](2+) cations whose charge is balanced by the BNPP(-) anions.     

Synthesis and characterisation of new titanium amino-alkoxides: precursors for the formation of TiO2 materials

Reaction of the amino-alkoxides HOCH(CH(2)NMe(2))(2) (Hbdmap) and HOC(CH(2)NMe(2))(3) (Htdmap) with [Ti(OR)(4)] yields a series of heteroleptic titanium alkoxides [Ti(OR)(4-n)(L)(n)] (L = bdmap, tdmap). Substitution of the monodentate alkoxide with the chelating alkoxides becomes progressively more difficult, with homogeneous products being obtained only for n = 1, 2. The structure of [Ti(OEt)(3)(bdmap)](2), a mu-OEt bridged dimer, has been determined. Hydrolysis of [Ti(OR)(2)(L)(2)], by adventitious moisture affords the dimeric oxo-alkoxides [Ti(O)(L)(2)](2), both of which have been characterised crystallographically. These two compounds have also been prepared by reaction of [Ti(NMe(2))(2)(L)(2)] with the hydrated metal salts [Zn(acac)(2).2H(2)O] and [Zn(OAc)(2).2H(2)O] using the intrinsic water molecules in these salts to react with the labile amido groups, though the former also produces Me(Me(2)N)C=C(H)C(O)Me from reaction of liberated HNMe(2) with the coordinated acac ligand, while the latter also affords the ligand exchange product [Zn(OAc)(bdmap)]. In neither case does the free dimethylamino group of [Ti(O)(L)(2)](2) coordinate a second metal. The dimeric structure of [Zn(OAc)(bdmap)](2) has been established, and the structure of the tetrameric oxo-alkoxide [Ti(O)(OPr(i))(OCH(2)CH(2)NMe(2))](4) is reported for comparison with others in this study. [Ti(OEt)(3)(bdmap)](2) has been used as a precursor in AACVD (Aerosol-Assisted Chemical Vapour Deposition) to generate amorphous TiO(2) films on glass at 440 degrees C, and TiO(2)@C nanoparticles of approximate diameter 350 nm with a carbon coating of width ca. 75 nm on heating in a sealed container at 700 degrees C.     

Tetraphosphinitoresorcinarene complexes: dynamic clusters with silver(I) and copper(I) halides

Silver(I) and copper(I) halide derivatives of several tetrakis(diphenylphosphinito)resorcinarene ligands are reported. The complexes [resorcinarene(O(2)CR)(4)(OPPh(2))(4)(M(5)X(5))], with resorcinarene = (PhCH(2)CH(2)CHC(6)H(2))(4), R = C(6)H(11), 4-C(6)H(4)Me, C(4)H(3)S, OCH(2)CCH, or OCH(2)Ph, M = Ag, X = Cl, Br, or I, M = Cu, and X = Cl or I, contain a crownlike [P(4)M(5)X(5)] metal halide cluster. These crown clusters were found to be dynamic in solution, as studied by variable-temperature NMR, and easily fragment to give the corresponding complexes containing [P(4)M(4)X(5)](-) and [P(4)M(2)(micro-X)](+) units. Reaction of pentasilver crown clusters with triflic acid gave the corresponding disilver complexes [resorcinarene(O(2)CR)(4)(OPPh(2))(4)]Ag(2)(micro-Cl)]]CF(3)SO(3). Thus, these resorcinarene-based ligands act as a platform for the easy and reversible assembly of copper(I) and silver(I) clusters with novel structures.     

New compounds from tellurocyanide rhenium cluster anions and 3d-transition metal cations coordinated with ethylenediamine

The compounds [Ni(en)(3)](2)[Re(6)Te(8)(CN)(6)].10H(2)O (1), [Ni(NH(3))(4)(en)](2)[Re(6)Te(8)(CN)(6)].2H(2)O (2), [Ni(NH(3))(2)(en)(2)][(Ni(en)(2))(3)(Re(4)Te(4)(CN)(12))(2)].38H(2)O (3), [Co(NH(3))(2)(en)(2)](2)[(Co(en)(2))Re(6)Te(8)(CN)(6)]Cl(2).H(2)O (4),and [(Zn(H(2)O)(en)(2))(Zn(en)(2))Re(6)Te(8)(CN)(6)].3H(2)O (5) (en = ethylenediamine) have been synthesized and characterized. Compounds 1, 4, and 5 have been synthesized by the diffusion of an aqueous (for 1 and 5) or an ammonia (for 4) solution of Cs(4)[Re(6)Te(8)(CN)(6)].2H(2)O into a glycerol solution of NiCl(2).6H(2)O (for 1), CoCl(2).6H(2)O (for 4), or ZnCl(2) (for 5). Compounds 2 and 3 have been synthesized by the reaction of an aqueous solution of Cs(4)[Re(6)Te(8)(CN)(6)].2H(2)O (for 2) or K(4)[Re(4)Te(4)(CN)(12)].5H(2)O (for 3) with an ammonia solution of Ni(en)(2)Cl(2). Compounds 1 and 2 are ionic whereas compounds 4 and 5 are one-dimensional polymers. Compound 3, a two-dimensional polymer, possesses hexagonal shaped channels of approximate diameter 10-12 A. Because the framework of compound 3 is robust, it is an attractive host for guest molecules of appropriate size and shape. The potential "guest" volume is about 37% of the unit cell volume.     

Pyrazolyl-bridged iridium dimers. 18.(1) influence of metal-metal bonding on the geometry of diiridium(II) adducts and hydrido-diiridium complexes formed from the diiridium(I) prototype [Ir(mu-pz)(PPh(3))(CO)](2) (pzH = Pyrazole) by dihydrogen addition or protonation

Slow uptake of molecular dihydrogen by the diiridium(I) prototype [Ir(mu-pz)(PPh(3))(CO)](2) (1: pzH = pyrazole) is accompanied by formation of a 1,2-dihydrido-diiridium(II) adduct [IrH(mu-pz)(PPh(3))(CO)](2) (2), for which an X-ray crystal structure determination reveals that (unlike in 1) the PPh(3) ligands are axial, with the hydrides occupying trans coequatorial positions across the Ir-Ir bond (2.672 A). Reaction with CCl(4) effects hydride replacement in 2, affording the monohydride Ir(2)H(Cl)(mu-pz)(2)(PPh(3))(2)(CO)(2) (3) in which Ir-Ir = 2.683 A. At one metal center, H is equatorial and PPh(3) is axial, while at the other, Cl is axial as is found in the symmetrically substituted product [Ir(mu-pz)(PPh(3))(CO)Cl](2) (4) (Ir-Ir = 2.754 A) that is formed by action of CCl(4) on 1. Treatment of 1 with I(2) yields the diiodo analogue 5 of 4, which reacts with LiAlH(4) to afford the isomorph Ir(2)H(I)(mu-pz)(2)(PPh(3))(2)(CO)(2) (6) of 3 (Ir-Ir = 2.684 A). Protonation (using HBF(4)) of 1 results in formation of the binuclear cation Ir(2)H(mu-pz)(2)(PPh(3))(2)(CO)(2)(+) (7: BF(4)(-) salt), which shows definitive evidence (from NMR) for a terminally bound hydride in solution (CH(2)Cl(2) or THF), but 7 crystallizes as an axially symmetric unit in which Ir-Ir = 2.834 A. Reaction of 7 with water or wet methanol leads to isolation of the cationic diiridium(III) products [Ir(2)H(2)(mu-OX)(mu-pz)(2)(PPh(3))(2)(CO)(2)]BF(4) (8, X = H; 9, X = Me).     

The first acetimino complexes of Rh(III). 4-imino-2-methylpentan-2-amino-Rh(III) complexes through metal-assisted intramolecular aldol-type condensation of two acetimino ligands

[Rh(Cp)Cl(mu-Cl)](2) (Cp = pentamethylcyclopentadienyl) reacts (i) with [Au(NH=CMe(2))(PPh(3))]ClO(4) (1:2) to give [Rh(Cp)(mu-Cl)(NH=CMe(2))](2)(ClO(4))(2) (1), which in turn reacts with PPh(3) (1:2) to give [Rh(Cp)Cl(NH=CMe(2))(PPh(3))]ClO(4) (2), and (ii) with [Ag(NH=CMe(2))(2)]ClO(4) (1:2 or 1:4) to give [Rh(Cp)Cl(NH=CMe(2))(2)]ClO(4) (3) or [Rh(Cp)(NH=CMe(2))(3)](ClO(4))(2).H(2)O (4.H(2)O), respectively. Complex 3 reacts (i) with XyNC (1:1, Xy = 2,6-dimethylphenyl) to give [Rh(Cp)Cl(NH=CMe(2))(CNXy)]ClO(4) (5), (ii) with Tl(acac) (1:1, acacH = acetylacetone) or with [Au(acac)(PPh(3))] (1:1) to give [Rh(Cp)(acac)(NH=CMe(2))]ClO(4) (6), (iii) with [Ag(NH=CMe(2))(2)]ClO(4) (1:1) to give 4, and (iv) with (PPN)Cl (1:1, PPN = Ph(3)P=N=PPh(3)) to give [Rh(Cp)Cl(imam)]Cl (7.Cl), which contains the imam ligand (N,N-NH=C(Me)CH(2)C(Me)(2)NH(2) = 4-imino-2-methylpentan-2-amino) that results from the intramolecular aldol-type condensation of the two acetimino ligands. The homologous perchlorate salt (7.ClO(4)) can be prepared from 7.Cl and AgClO(4) (1:1), by treating 3 with a catalytic amount of Ph(2)C=NH, in an atmosphere of CO, or by reacting 4with (PPN)Cl (1:1). The reactions of 7.ClO(4) with AgClO(4) and PTo(3) (1:1:1, To = C(6)H(4)Me-4) or XyNC (1:1:1) give [Rh(Cp)(imam)(PTo(3))](ClO(4))(2).H(2)O (8) or [Rh(Cp)(imam)(CNXy)](ClO(4))(2) (9), respectively. The crystal structures of 3 and 7.Cl have been determined.     

On the reactivity toward ketones of new methyl amino complexes of Rh(III) and Ag(I). Synthesis of ortho-rhodiated acetophenone methyl imine complexes

MeNH(2) reacts with silver salts AgX (2:1) to give [Ag(NH(2)Me)(2)]X [X = TfO = CF(3)SO(3) (1.TfO) and ClO(4) (1.ClO(4))]. Neutral mono(amino) Rh(III) complexes [Rh(Cp*)Cl(2)(NH(2)R)] [R = Me (2a), To = C(6)H(4)Me-4 (2b)] have been prepared by reacting [Rh(Cp*)Cl(mu-Cl)](2) with RNH(2) (1:2). The following cationic methyl amino complexes have also been prepared: [Rh(Cp*)Cl(NH(2)Me)(PPh(3))]TfO (3.TfO), from [Rh(Cp*)Cl(2)(PPh(3))] and 1.TfO (1:1); [Rh(Cp*)Cl(NH(2)R)2]X, where R = Me, X = Cl, (4a.Cl), from [Rh(Cp*)Cl(mu-Cl)]2 and MeNH2 (1:4), or R = Me, X = ClO4 (4a.ClO4), from 4a.Cl and NaClO4 (1:4.8), or R = To, X = TfO (4b.TfO), from [Rh(Cp*)Cl(mu-Cl)](2), ToNH(2) and TlTfO (1:4:2); [Rh(Cp*)(NH(2)Me)(tBubpy)](TfO)(2) (tBubpy = 4,4'-di-tert-butyl-2,2'-bipyridine, 5.TfO), from 2a, TlTfO and tBubpy (1:2:1); [Rh(Cp*)(NH(2)Me)(3)](TfO)2 (6.TfO) from [Rh(Cp*)Cl(mu-Cl)](2) and 1.TfO (1:4). 2-6 constitute the first family of methyl amino complexes of rhodium. 1 and 4a.ClO(4) react with acetone to give, respectively, the methyl imino complexes [Ag{N(Me)=CMe(2)}()]X [X = TfO (7.TfO), ClO(4) (7.ClO(4))], and [Rh(Cp*)Cl(Me-imam)]ClO(4) [8.ClO(4), Me-imam = N,N'-N(Me)=C(Me)CH(2)C(Me)(2)NHMe]. 7.X (X = TfO, ClO(4)) are new members of the small family of methyl acetimino complexes of any metal whereas 8.ClO4 results after a double acetone condensation to give the corresponding bis(methyl acetimino) complex and an aldol-like condensation of the two imino ligands. The acetimino complex [Ag(NH=CMe(2))(2)]ClO(4) reacts with [Rh(Cp*)Cl(imam)]ClO(4) [1:1, imam = N,N'-NH=C(Me)CH(2)C(Me)(2)NH(2)] to give [Rh(Cp*)(imam)(NH=CMe(2))](ClO(4))(2) (9a.ClO(4)). 8.ClO(4) reacts with AgClO(4) (1:1) in MeCN to give [Rh(Cp*)(Me-imam)(NCMe)](ClO(4))2 (9b.ClO(4)), which in turn reacts with XyNC (Xy = C(6)H(3)Me(2)-2,6) or with MeNH(2) (1:1) to give [Rh(Cp*)(Me-imam)L](ClO(4))(2) [L = XyNC (9c.ClO(4)), MeNH(2) (9d.ClO(4))]. 6.TfO reacts with acetophenone to give [Rh(Cp*){C,N-C(6)H(4)C(Me)=N(Me)-2}(NH(2)Me)]TfO (10a.TfO), the first complex resulting from such a condensation and cyclometalation reaction. In turn, 10a.TfO reacts with isocyanides RNC (1:1) at room temperature to give [Rh(Cp*){C,N-C(6)H(4)C(Me)=NMe-2}(CNR)]TfO [R = tBu (10b.TfO), Xy (10c.TfO)], or 1:12 at 60 degrees C to give [Rh(Cp*){C,N-C(=NXy)C(6)H(4)C(Me)=N(Me)-2}(CNXy)]TfO (11.TfO). The crystal structures of 9a.ClO(4).acetone-d6, 9c.ClO(4), and 10a.TfO have been determined.     

Ni(P(Ph)2N(C6H4X)2)2]2+ complexes as electrocatalysts for H2 production: effect of substituents, acids, and water on catalytic rates

A series of mononuclear nickel(II) bis(diphosphine) complexes [Ni(P(Ph)(2)N(C6H4X)(2))(2)](BF(4))(2) (P(Ph)(2)N(C6H4X)(2) = 1,5-di(para-X-phenyl)-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane; X = OMe, Me, CH(2)P(O)(OEt)(2), Br, and CF(3)) have been synthesized and characterized. X-ray diffraction studies reveal that [Ni(P(Ph)(2)N(C6H4Me)(2))(2)](BF(4))(2) and [Ni(P(Ph)(2)N(C6H4OMe)(2))(2)](BF(4))(2) are tetracoordinate with distorted square planar geometries. The Ni(II/I) and Ni(I/0) redox couples of each complex are electrochemically reversible in acetonitrile with potentials that are increasingly cathodic as the electron-donating character of X is increased. Each of these complexes is an efficient electrocatalyst for hydrogen production at the potential of the Ni(II/I) couple. The catalytic rates generally increase as the electron-donating character of X is decreased, and this electronic effect results in the favorable but unusual situation of obtaining higher catalytic rates as overpotentials are decreased. Catalytic studies using acids with a range of pK(a) values reveal that turnover frequencies do not correlate with substrate acid pK(a) values but are highly dependent on the acid structure, with this effect being related to substrate size. Addition of water is shown to dramatically increase catalytic rates for all catalysts. With [Ni(P(Ph)(2)N(C6H4CH2P(O)(OEt)2)(2))(2)](BF(4))(2) using [(DMF)H](+)OTf(-) as the acid and with added water, a turnover frequency of 1850 s(-1) was obtained.     

Octanuclear and nonanuclear supramolecular copper(II) complexes with linear "tritopic" ligands: structural and magnetic studies

The structures and magnetic properties of self-assembled copper(II) clusters and grids with the "tritopic" ligands 2poap (a), Cl2poap (b), m2poap (c), Cl2pomp (d), and 2pomp (e) are described [ligands derived by reaction of 4-R-2,6-pyridinedicarboxylic hydrazide (R = H, Cl, MeO) with 2-pyridinemethylimidate (a-c, respectively) or 2-acetylpyridine (d, R = Cl; e, R = H)]. Cl2poap and Cl2pomp self-assemble with Cu(NO(3))(2) to form octanuclear "pinwheel" cluster complexes [Cu(8)(Cl2poap-2H)(4)(NO(3))(8)].20H(2)O (1) and [Cu(8)(Cl2pomp-2H)(4)(NO(3))(8)].15H(2)O (2), built on a square [2 x 2] grid with four pendant copper arms, using "mild" reaction conditions. Similar reactions of Cl2pomp and 2pomp with Cu(ClO(4))(2) produce pinwheel clusters [Cu(8)(Cl2pomp-2H)(4)(H(2)O)(8)](ClO(4))(8).7H(2)O (3) and [Cu(8)(2pomp-2H)(4)(H(2)O)(8)](ClO(4))(8) (4), respectively. Heating a solution of 1 in MeOH/H(2)O produces a [3 x 3] nonanuclear square grid complex, [Cu(9)(Cl2poap-H)(3)(Cl2poap-2H)(3)](NO(3))(9).18H(2)O (5), which is also produced by direct reaction of the ligand and metal salt under similar conditions. Reaction of m2poap with Cu(NO(3))(2) produces only the [3 x 3] grid [Cu(9)(m2poap-H)(2)(m2poap-2H)(4)](NO(3))(8).17H(2)O (6) under similar conditions. Mixing the tritopic ligand 2poap with pyridine-2,6-dicarboxylic acid (picd) in the presence of Cu(NO(3))(2) produces a remarkable mixed ligand, nonanuclear grid complex [Cu(9)(2poap-H)(4)(picd-H)(3)(picd-2H)](NO(3))(9).9H(2)O (7), in which aromatic pi-stacking interactions are important in stabilizing the structure. Complexes 1-3 and 5-7 involve single oxygen atom (alkoxide) bridging connections between adjacent copper centers, while complex 4 has an unprecedented mixed micro-(N-N) and micro-O metal ion connectivity. Compound 1 (C(76)H(92)N(44)Cu(8)O(50)Cl(4)) crystallizes in the tetragonal system, space group I, with a = 21.645(1) A, c = 12.950(1) A, and Z = 2. Compound 2 (C(84)H(88)N(36)O(44)Cl(4)Cu(8)) crystallizes in the tetragonal system, space group I, with a = 21.2562(8) A, c = 12.7583(9) A, and Z = 2. Compound 4 (C(84)H(120)N(28)O(66)Cl(8)Cu(8)) crystallizes in the tetragonal system, space group I4(1)/a, with a = 20.7790(4) A, c = 32.561(1) A, and Z = 4. Compound 7(C(104)H(104)N(46)O(56)Cu(9)) crystallizes in the triclinic system, space group P, with a = 15.473(1) A, b = 19.869(2) A, c = 23.083(2) A, alpha = 88.890(2) degrees, beta = 81.511(2) degrees, gamma = 68.607(1) degrees, and Z = 2. All complexes exhibit dominant intramolecular ferromagnetic exchange coupling, resulting from an orthogonal bridging arrangement within each polynuclear structure.     

Molecular nitrides containing group 4 and 5 metals: single and double azatitanocubanes

Treatment of [[Ti(eta(5)-C(5)Me(5))(micro-NH)](3)(micro(3)-N)] (1) with the imido complexes [Ti(NAr)Cl(2)(py)(3)] (Ar=2,4,6-C(6)H(2)Me(3)) and [Ti(NtBu)Cl(2)(py)(3)] in toluene affords the single azatitanocubanes [[Cl(2)(ArN)Ti]( micro(3)-NH)(3)[Ti(3)(eta(5)-C(5)Me(5))(3)(micro(3)-N)]].(C(7)H(8)) (2.C(7)H(8)) and [[Cl(2)Ti](micro(3)-N)(2)(micro(3)-NH)[Ti(3)(eta(5)-C(5)Me(5))(3)(micro(3)-N)]] (3), respectively. Similar reactions of complex 1 with the niobium and tantalum imido derivatives [[M(NtBu)(NHtBu)Cl(2)(NH(2)tBu)](2)] (M=Nb, Ta) in toluene give the single azaheterometallocubanes [[Cl(2)(tBuN)M](micro(3)-N)(micro(3)-NH)(2)[Ti(3)(eta(5)-C(5)Me(5))(3)(micro(3)-N)]] (M=Nb (4), Ta (5)), both complexes react with 2,4,6-trimethylaniline to yield the analogous species [[Cl(2)(ArN)M](micro(3)-N)(micro(3)-NH)(2)[Ti(3)(eta(5)-C(5)Me(5))(3)(micro(3)-N)]].(C(7)H(8)) (Ar=2,4,6-C(6)H(2)Me(3), M=Nb (6.C(7)H(8)), Ta (7.C(7)H(8))). Also the azaheterodicubanes [M[micro(3)-N)(2)(micro(3)-NH)](2)[Ti(3)(eta(5)-C(5)Me(5))(3)(micro(3)-N)](2)].2C(7)H(8) [M=Ti (8.2C(7)H(8)), Zr (9.2C(7)H(8))], and [M[(micro(3)-N)(5)(micro(3)-NH)][Ti(3)(eta(5)-C(5)Me(5))(3)(micro(3)-N)](2)].2 C(7)H(8) (Nb (10.2C(7)H(8)), Ta (11.2C(7)H(8))) were prepared from 1 and the homoleptic dimethylamido complex [M(NMe(2))(x)] (x=4, M=Ti, Zr; x=5, M=Nb, Ta) in toluene at 150 degrees C. X-ray crystal structure determinations were performed for 6 and 10, which revealed a cube- and double-cube-type core, respectively. For complexes 2 and 4-7 we observed and studied by DNMR a rotation or trigonal-twist of the organometallic ligands [[Ti(eta(5)-C(5)Me(5))(micro-NH)](3)(micro(3)-N)] (1) and [(micro(3)-N)(micro(3)-NH)(2)[Ti(3)(eta(5)-C(5)Me(5))(3)(micro(3)-N)]](1-). Density functional theory calculations were carried out on model complexes of 2, 3, and 8 to establish and understand their structures.     

Dinuclear zinc(II) complexes of tetraiminodiphenol macrocycles and their interactions with carboxylate anions and amino acids. Photoluminescence, equilibria, and structure

The reaction equilibria [H(4)L](2+) + Zn(OAc)(2) right harpoon over left harpoon [Zn(H(2)L)](2+) + 2HOAc (K(1)) and [Zn(H(2)L)](2+) + Zn(OAc)(2) right harpoon over left harpoon [Zn(2)L](2+) + 2HOAc (K(2)), involving zinc acetate and the perchlorate salts of the tetraiminodiphenol macrocycles [H(4)L(1)(-)(3)](ClO(4))(2), the lateral (CH(2))(n)() chains of which vary between n = 2 and n = 4, have been studied by spectrophotometric and spectrofluorimetric titrations in acetonitrile. The photoluminescence behavior of the complexes [Zn(2)L(1)](ClO(4))(2), [Zn(2)L(2)(H(2)O)(2)](ClO(4))(2), [Zn(2)L(2)(mu-O(2)CR)](ClO(4)) (R = CH(3), C(6)H(5), p-CH(3)C(6)H(4), p-OCH(3)C(6)H(4), p-ClC(6)H(4), p-NO(2)C(6)H(4)), and [Zn(2)L(3)(mu-OAc)](ClO(4)) have been investigated. The X-ray crystal structures of the complexes [Zn(2)L(2)(H(2)O)(2)](ClO(4))(2), [Zn(2)L(3)(mu-OAc)](ClO(4)), and [Zn(2)L(2)(mu-OBz)(OBz)(H(3)O)](ClO(4)) have been determined. The complex [Zn(2)L(2)(mu-OBz)(OBz)(H(3)O)](ClO(4)) in which the coordinated water molecule is present as the hydronium ion (H(3)O(+)) on deprotonation gives rise to the neutral dibenzoate-bridged compound [Zn(2)L(2)(mu-OBz)(2)].H(2)O. The equilibrium constants (K) for the reaction [Zn(2)L(2)(H(2)O)(2)](2+) + A(-) right harpoon over left harpoon [Zn(2)L(2)A](+) + 2H(2)O (K), where A(-) = acetate, benzoate, or the carboxylate moiety of the amino acids glycine, l-alanine, l-histidine, l-valine, and l-proline, have been determined spectrofluorimetrically in aqueous solution (pH 6-7) at room temperature. The binding constants (K) evaluated for these systems vary in the range (1-8) x 10(5).