Facile oxidative addition of water at iridium: reactivity of trans-[Ir(4-C5NF4)(H)(OH)(PiPr3)2] towards CO2 and NH3

A reaction of trans-[Ir(4-C(5)NF(4))(η(2)-C(2)H(4))(PiPr(3))(2)] (1) with an excess of water in THF at room temperature affords the hydrido hydroxo complex trans-[Ir(4-C(5)NF(4))(H)(OH)(PiPr(3))(2)] (2). Treatment of 2 with CO furnishes trans-[Ir(4-C(5)NF(4))(H)(OH)(CO)(PiPr(3))(2)] (3). Reductive elimination of water from 3 leads to the formation of the iridium(I) carbonyl complex trans-[Ir(4-C(5)NF(4))(CO)(PiPr(3))(2)] (4). The insertion of CO(2) into the Ir-O bond of 2 forms the hydrido hydrogencarbonato complex trans-[Ir(4-C(5)NF(4))(H)(κ(2)-(O,O)-O(2)COH)(PiPr(3))(2)] (5). Treatment of 2 with NH(3) in C(6)D(6) yields trans-[Ir(4-C(5)NF(4))(H)(OH)(NH(3))(PiPr(3))(2)] (6). Storage of the reaction mixture at room temperature reveals the formation of the N-H activation product [Ir(4-C(5)NF(4))(H)(μ-NH(2))(NH(3))(PiPr(3))](2) (7).     

Electrochemical cleavage of N=N bonds at a Mo2(mu-SMe)3 site relevant to the biological reduction of dinitrogen at a bimetallic sulfur centre

The reduction of diazene complexes [Mo(2)Cp(2)(mu-SMe)(3)(mu-eta(2)-H-N=N-R)](+) (R=Ph (3 a); Me (3 b)) and of the hydrazido(2-) derivative [Mo(2)Cp(2)(mu-SMe)(3)[mu-eta(1)-N=N(Me)H]](+) (1 b) has been studied by cyclic voltammetry, controlled-potential electrolysis, and coulometry in THF. The electrochemical reduction of 3 a in the presence of acid leads to cleavage of the N=N bond and produces aniline and either the amido complex [Mo(2)Cp(2)(mu-SMe)(3)(mu-NH(2))] 4 or the ammine complex [Mo(2)Cp(2)(mu-SMe)(3)(NH(3))(X)] 5, depending on the initial concentration of acid (HX=HTsO or CF(3)CO(2)H). The N=N bond of the methyldiazene analogue 3 b is not cleaved under the same conditions. The ability of 3 a but not 3 b to undergo reductive cleavage of the N=N bond is attributed to electronic control of the strength of the Mo-N(R) bond by the R group. The electrochemical reduction of the methylhydrazido(2-) compound 1 b in the presence of HX also results in cleavage of the N=N bond, with formation of methylamine, 4 (or 5) and the methyldiazenido complex [Mo(2)Cp(2)(mu-SMe)(3)(mu-eta(1)-N=N-Me)]. Formation of the last of these complexes indicates that two mechanisms (N=N bond cleavage and possibly H(2) production) are operative. A pathway for the reduction of N(2) at a dinuclear site of FeMoco is proposed on the basis of these results.     

Molecular and electronic structures of iron(II)/(III) complexes containing N,S-coordinated,closed-shell o-aminothiophenolato(1-) and o-iminothiophenolato(2-) ligands

The coordination chemistry of the ligands o-aminothiophenol, H(abt), 4,6-di-tert-butyl-2-aminothiophenol, H[L(AP)], and 1,2-ethanediamine-N,N'-bis(2-benzenethiol), H(4)('N(2)S(2')), with FeCl(2) under strictly anaerobic and increasingly aerobic conditions has been systematically investigated. Using strictly anaerobic conditions, the neutral, air-sensitive, yellow complexes (mu-S,S)[Fe(II)(abt)(2)](2) (1), (mu-S,S)[Fe(II)(L(AP))(2)](2).8CH(3)OH (2), and (mu-S,S)[Fe(II)('H(2)N(2)S(2'))](2).CH(3)CN (3) containing high spin ferrous ions have been isolated where (abt)(1-), (L(AP))(1-), and ('H(2)N(2)S(2'))(2-) represent the respective N,S-coordinated, aromatic o-aminothiophenolate derivative of these ligands. When the described reaction was carried out in the presence of trace amounts of O(2) and [PPh(4)]Br, light-green crystals of [PPh(4)][Fe(II)(abt)(2)(itbs)].[PPh(4)]Br (4) were isolated. The anion [Fe(II)(abt)(2)(itbs)](-) contains a high spin ferrous ion, two N,S-coordinated o-aminophenolate(1-) ligands, and an S-bound, monoanionic o-iminothionebenzosemiquinonate(1-) pi radical, (itbs)(-). Complex 4 possesses an S(t) = 3/2 ground state. In the absence of [PPh(4)]Br and presence of a base NEt(3) and a little O(2), the ferric dimer (mu-NH,NH)[Fe(III)(L(AP))(L(IP))](2) (5a) and its isomer (mu-S,S)[Fe(III)(L(AP))(L(IP))](2) (5b) formed. (L(IP))(2-) represents the aromatic o-iminothiophenolate(2-) dianion of H[L(AP)]. The structures of compounds 2, 4, and 5a have been determined by X-ray crystallography at 100(2) K. Zero-field M?ssbauer spectroscopy of 1, 2, 3, and 4 unambiguously shows the presence of high spin ferrous ions: The isomer shift at 80 K is in the narrow range 0.85-0.92 mm s(-1), and a large quadrupole splitting, |DeltaE(Q)|, in the range 3.24-4.10 mm s(-1), is observed. In contrast, 5a and 5b comprise both intermediate spin ferric ions (S(Fe) = 3/2) which couple antiferromagnetically in the dinuclear molecules yielding an S(t) = 0 ground state.     

Octahedral Ru(II) amido complexes TpRu(L)(L')(NHR) (Tp = hydridotris(pyrazolyl)borate; L = L' = P(OMe)3 or PMe3 or L = CO and L' = PPh3; R = H,Ph, or tBu): synthesis,characterization, and reactions with weakly acidic C-H bonds

The octahedral Ru(II) amine complexes [TpRu(L)(L')(NH(2)R)][OTf] (L = L' = PMe(3), P(OMe)(3) or L = CO and L' = PPh(3); R = H or (t)Bu) have been synthesized and characterized. Deprotonation of the amine complexes [TpRu(L)(L')(NH(3))][OTf] or [TpRu(PMe(3))(2)(NH(2)(t)Bu)][OTf] yields the Ru(II) amido complexes TpRu(L)(L')(NH(2)) and TpRu(PMe(3))(2)(NH(t)Bu). Reactions of the parent amido complexes or TpRu(PMe(3))(2)(NH(t)Bu) with phenylacetylene at room temperature result in immediate deprotonation to form ruthenium-amine/phenylacetylide ion pairs, and heating a benzene solution of the [TpRu(PMe(3))(2)(NH(2)(t)Bu)][PhC(2)] ion pair results in the formation of the Ru(II) phenylacetylide complex TpRu(PMe(3))(2)(C[triple bond]CPh) in >90% yield. The observation that [TpRu(PMe(3))(2)(NH(2)(t)Bu)][PhC(2)] converts to the Ru(II) acetylide with good yield while heating the ion pairs [TpRu(L)(L')(NH(3))][PhC(2)] yields multiple products is attributed to reluctant dissociation of ammonia compared with the (t)butylamine ligand (i.e., different rates for acetylide/amine exchange). These results are consistent with ligand exchange reactions of Ru(II) amine complexes [TpRu(PMe(3))(2)(NH(2)R)][OTf] (R = H or (t)Bu) with acetonitrile. The previously reported phenyl amido complexes TpRuL(2)(NHPh) [L = PMe(3) or P(OMe)(3)] react with 10 equiv of phenylacetylene at elevated temperature to produce Ru(II) acetylide complexes TpRuL(2)(C[triple bond]CPh) in quantitative yields. Kinetic studies indicate that the reaction of TpRu(PMe(3))(2)(NHPh) with phenylacetylene occurs via a pathway that involves TpRu(PMe(3))(2)(OTf) or [TpRu(PMe(3))(2)(NH(2)Ph)][OTf] as catalyst. Reactions of 1,4-cyclohexadiene with the Ru(II) amido complexes TpRu(L)(L')(NH(2)) (L = L' = PMe(3) or L = CO and L' = PPh(3)) or TpRu(PMe(3))(2)(NH(t)Bu) at elevated temperatures result in the formation of benzene and Ru hydride complexes. TpRu(PMe(3))(2)(H), [Tp(PMe(3))(2)Ru[double bond]C[double bond]C(H)Ph][OTf], [Tp(PMe(3))(2)Ru=C(CH(2)Ph)[N(H)Ph]][OTf], and [TpRu(PMe(3))(3)][OTf] have been independently prepared and characterized. Results from solid-state X-ray diffraction studies of the complexes [TpRu(CO)(PPh(3))(NH(3))][OTf], [TpRu(PMe(3))(2)(NH(3))][OTf], and TpRu(CO)(PPh(3))(C[triple bond]CPh) are reported.     

Synthesis of the (N2)3- radical from Y2+ and its protonolysis reactivity to form (N2H2)2- via the Y[N(SiMe3)2]3/KC8 reduction system

Examination of the Y[N(SiMe(3))(2)](3)/KC(8) reduction system that allowed isolation of the (N(2))(3-) radical has led to the first evidence of Y(2+) in solution. The deep-blue solutions obtained from Y[N(SiMe(3))(2)](3) and KC(8) in THF at -35 °C under argon have EPR spectra containing a doublet at g(iso) = 1.976 with a 110 G hyperfine coupling constant. The solutions react with N(2) to generate (N(2))(2-) and (N(2))(3-) complexes {[(Me(3)Si)(2)N](2)(THF)Y}(2)(μ-η(2):η(2)-N(2)) (1) and {[(Me(3)Si)(2)N](2)(THF)Y}(2)(μ-η(2):η(2)-N(2))[K(THF)(6)] (2), respectively, and demonstrate that the Y[N(SiMe(3))(2)](3)/KC(8) reaction can proceed through an Y(2+) intermediate. The reactivity of (N(2))(3-) radical with proton sources was probed for the first time for comparison with the (N(2))(2-) and (N(2))(4-) chemistry. Complex 2 reacts with [Et(3)NH][BPh(4)] to form {[(Me(3)Si)(2)N](2)(THF)Y}(2)(μ-N(2)H(2)), the first lanthanide (N(2)H(2))(2-) complex derived from dinitrogen, as well as 1 as a byproduct, consistent with radical disproportionation reactivity.     

Molecular and electronic structures of iron complexes containing N,S-coordinated,open-shell o-iminothionebenzosemiquinonate(1-) pi radicals

The reaction of the dinuclear species (mu-NH,NH)[Fe(III)(L(IP))(L(AP))](2) dissolved in CH(2)Cl(2) with dioxygen affords black microcrystals of diamagnetic (mu-S,S)[Fe(III)(L(IP))(L(ISQ))](2).n-hexane (6) upon the addition of n-hexane, where (L(IP))(2)(-) represents the dianion of 4,6-di-tert-butyl-2-aminothiophenol, (L(AP))(-) is the corresponding monoanion, and (L(ISQ))(-) is the corresponding o-iminothionebenzosemiquinonate(1-) pi radical monoanion; similarly, the dianion ('H(2)N(2)S(2)')(2)(-) is derived from 1,2-ethanediamine-N,N'-bis(2-benzenethiol), and ('N(2)S(2)(*)')(3)(-) is its monoradical trianion. The above reaction in a CH(2)Cl(2)/CH(3)OH (1:1) mixture yields the diamagnetic isomer (mu-NH,NH)[Fe(III)(L(IP))(L(ISQ))](2).5CH(3)OH (7), whereas air oxidation of (mu-S,S)[Fe(II)('H(2)N(2)S(2)')](2) in CH(3)CN yields diamagnetic (mu-S,S)[Fe(III)('N(2)S(2)(*)')](2) (8). Complexes 6 and 8 were shown to undergo addition reactions with phosphines, phosphites, or cyanide affording the following complexes: trans-[Fe(II)(L(ISQ))(2)(P(OPh)(3))] (9; S(t) = 0) and [N(n-Bu)(4)][Fe(II)(L(ISQ))(2)(CN)] (S(t) = 0). Oxidation of 6 in CH(2)Cl(2) with iodine, bromine, and chlorine respectively yields black microcrystals of [Fe(III)(L(ISQ))(2)X] (X = I, Br, or Cl) with S(t) = (1)/(2). The structures of complexes 6-9 have been determined by X-ray crystallography at 100 K. The oxidation level of the ligands and iron ions in all complexes has been unequivocally established, as indicated by crystallography; electron paramagnetic resonance, UV-vis, and M?ssbauer spectroscopies; and magnetic-susceptibility measurements. The N,S-coordinated o-iminothionebenzosemiquinonate(1-) pi radicals have been identified in all new complexes. The electronic structures of the new complexes have been determined, and it is shown that no evidence for iron oxidation states >III is found in this chemistry.     

General synthesis of (salen)ruthenium(III) complexes via N...N coupling of (salen)ruthenium(VI) nitrides

Reaction of [Ru (VI)(N)(L (1))(MeOH)] (+) (L (1) = N, N'-bis(salicylidene)- o-cyclohexylenediamine dianion) with excess pyridine in CH 3CN produces [Ru (III)(L (1))(py) 2] (+) and N 2. The proposed mechanism involves initial equilibrium formation of [Ru (VI)(N)(L (1))(py)] (+), which undergoes rapid N...N coupling to produce [(py)(L (1))Ru (III) N N-Ru (III)(L (1))(py)] (2+); this is followed by pyridine substituion to give the final product. This ligand-induced N...N coupling of Ru (VI)N is utilized in the preparation of a series of new ruthenium(III) salen complexes, [Ru (III)(L)(X) 2] (+/-) (L = salen ligand; X = H 2O, 1-MeIm, py, Me 2SO, PhNH 2, ( t )BuNH 2, Cl (-) or CN (-)). The structures of [Ru (III)(L (1))(NH 2Ph) 2](PF 6) ( 6), K[Ru (III)(L (1))(CN) 2] ( 9), [Ru (III)(L (2))(NCCH 3) 2][Au (I)(CN) 2] ( 11) (L (2) = N, N'-bis(salicylidene)- o-phenylenediamine dianion) and [N ( n )Bu 4][Ru (III)(L (3))Cl 2] ( 12) (L (3) = N, N'-bis(salicylidene)ethylenediamine dianion) have been determined by X-ray crystallography.     

Synthesis and characterization of new biphenolate and binaphtholate rare-Earth-metal amido complexes: catalysts for asymmetric olefin hydroamination/cyclization

Monomeric diolate amido yttrium complexes [Y[diolate][N(SiHMe(2))(2)](thf)(2)] can be prepared in good yield by treating [Y[N(SiHMe(2))(2)](3)(thf)(2)] with either 3,3'-di-tert-butyl-5,5',6,6'-tetramethyl-1,1'-biphenyl-2,2'-diol (H(2)(Biphen)), 3,3'-bis(2,4,6-triisopropylphenyl)-2,2'-dihydroxy-1,1'-dinaphthyl (H(2)(Trip(2)BINO)) or 3,3'-bis(2,6-diisopropylphenyl)-2,2'-dihydroxy-1,1'-dinaphthyl (H(2)(Dip(2)BINO)) in racemic and enantiopure form. The racemic complex [Y(biphen)[N(SiHMe(2))(2)](thf)(2)] dimerizes upon heating to give the heterochiral complex (R,S)-[Y(biphen)[N(SiHMe(2))(2)](thf)](2). The corresponding dimeric heterochiral lanthanum complex was the sole product in the reaction of H(2)(Biphen) with [La[N(SiHMe(2))(2)](3)(thf)(2)]. Single-crystal X-ray diffraction of both dimeric complexes revealed that the two Ln(biphen)[N(SiHMe(2))(2)](thf) fragments are connected through bridging phenolate groups of the biphenolate ligands. The two different phenolate groups undergo an intramolecular exchange process in solution leading to their equivalence on the NMR timescale. All complexes were active catalysts for the hydroamination/cyclization of aminoalkynes and aminoalkenes at elevated temperature, with [Y((R)-dip(2)bino)[N(SiHMe(2))(2)](thf)(2)] being the most active one giving enantioselectivities of up to 57 % ee. Kinetic resolution of 2-aminohex-5-ene proceeded with this catalyst with 6.4:1 trans selectivity to give 2,5-dimethylpyrrolidine with a k(rel) of 2.6.     

Reactions of phthalazine, quinazoline, 4,7-phenanthroline and 2,3'-bipyridine with ruthenium carbonyl

The reactions of [Ru(3)(CO)(12)] with four aromatic diazines have been studied in THF at reflux temperature. With phthalazine (L(1)), the compound [Ru(3)(μ-κ(2)N(2)N(3)-L(1))(μ-CO)(3)(CO)(7)] (1), which contains an intact phthalazine ligand in an axial position bridging an Ru-Ru edge through both N atoms, is initially formed but it reacts with more phthalazine to give [Ru(3)(κN(2)-L(1))(μ-κ(2)N(2)N(3)-L(1))(μ-CO)(3)(CO)(6)] (2), in which a π-π stacking interaction between the aromatic rings of both ligands determines their position in cluster axial sites on the same face of the Ru(3) triangle. With quinazoline (HL(2)), the cyclometalated hydrido decacarbonyl derivative [Ru(3)(μ-H)(μ-κ(2)N(3)C(4)-L(2))(CO)(10)] (3) is initially produced but it partially decarbonylates under the reaction conditions to give [Ru(6)(μ-H)(2)(μ-κ(2)N(3)C(4)-L(2))(μ(3)-κ(3)-N(1)N(3)C(4)-L(2))(CO)(19)] (4), which results from the displacement of a CO ligand of 3 by the uncoordinated N(1) atom of another molecule of 3. With 4,7-phenanthroline (H(2)L(3)), the stepwise formation of the cyclometalated derivatives [Ru(3)(μ-H)(μ-κ(2)N(4)C(3)-HL(3))(CO)(10)] (5) and two isomers of [Ru(6)(μ-H)(2)(μ(4)-κ(4)N(4)C(3)N(7)C(8)-L(3))(CO)(20)] (6a, 6b) takes place. In compounds 6a and 6b, two Ru(3)(μ-H)(CO)(10) trinuclear units are symmetrically (C(2) in 6a or C(S) in 6b) bridged by a doubly-cyclometalated 4,7-phenanthroline ligand. With 2,3'-bipyridine (HL(4)), two products have been isolated, [Ru(3)(μ-H)(μ-κ(2)N(3')C(4')-L(4))(CO)(10)] (7) and [Ru(3)(μ-H)(μ-κ(3)N(2)N(3')C(2')-L(4))(CO)(9)] (8). While compound 7 contains an N(3')C(4')-cyclometalated 2,3'-bipyridine, in compound 8 an N(3')C(2')-cyclometalation is accompanied by the coordination of the N(2) atom of the remaining pyridine fragment. The structures of compounds 2, 3, 4, 6a and 8 have been determined by X-ray diffraction crystallography.     

Probing the catalytic potential of chloro nitrosyl rhenium(I) complexes

The reduction of the mononitrosyl Re(II) salt [NMe(4)](2)[ReCl(5)(NO)] (1) with zinc in acetonitrile afforded the Re(i) dichloride complex [ReCl(2)(NO)(CH(3)CN)(3)] (2). Subsequent ligand substitution reactions with PCy(3), PiPr(3) and P(p-tolyl)(3) afforded the bisphosphine Re(i) complexes [ReCl(2)(NO)(PR(3))(2)(CH(3)CN)] (3, R = Cy a, iPr b, p-tolyl c) in good yields. The acetonitrile ligand in 3 is labile, permitting its replacement with H(2) (1 bar) to afford the dihydrogen Re(I) complexes [ReCl(2)(NO)(PR(3))(2)(η(2)-H(2))] (4, R = Cy a, iPr b). The catalytic activity of 2, 3 and 4 in hydrogen-related catalyses including dehydrocoupling of Me(2)NH·BH(3), dehydrogenative silylation of styrenes, and hydrosilylation of ketones and aryl aldehydes were investigated, with the main focus on phosphine and halide effects. In the dehydrocoupling of Me(2)NH·BH(3), the phosphine-free complex 2 exhibits the same activity as the bisphosphine-substituted systems. In the dehydrogenative silylation of styrenes, 3a and 4a bearing PCy(3) ligands exhibit high catalytic activities. Monochloro Re(I) hydrides [Re(Cl)(H)(NO)(PR(3))(2)(CH(3)CN)] (5, R = Cy a, iPr b) were proven to be formed in the initiation pathway. The phosphine-free complex 2 showed in dehydrogenative silylations even higher activity than the bisphosphine derivatives, which further emphasizes the importance of a facile phosphine dissociation in the catalytic process. In the hydrosilylation of ketones and aryl aldehydes, at least one rhenium-bound phosphine is required to ensure high catalytic activity.     

A novel series of materials composed of arrays of vanadium oxide container molecules, [V18O42(X)] (X = H2O,Cl-, Br-): synthesis and characterization of [M2(H2N(CH2)2NH2)5][(M(H2N(CH2)2NH2)2]2V18O42(X)]. 9H2O (M = Zn,Cd)

The synthesis and characterization of the novel systems [Zn(2)(H(2)N(CH(2))(2)NH(2))(5)][(Zn(H(2)N(CH(2))(2)NH(2))(2))(2)V(18)O(42)(H(2)O)].9H(2)O (1), [Cd(2)(H(2)N(CH(2))(2)NH(2))(5)][(Cd(H(2)N(CH(2))(2)NH(2))(2))(2)V(18)O(42)(Br)].9H(2)O (2), and [Zn(2)(H(2)N(CH(2))(2)NH(2))(5)][(Zn(H(2)N(CH(2))(2)NH(2))(2))(2)V(18)O(42)(Cl)].9H(2)O (3) have been described. These materials represent a new class of solids that have been prepared by combining conventional coordination compounds with spherical polyoxovanadate clusters. The isomorphous structures of these hybrid solids consist of two-dimensional arrays of container cluster molecules [V(18)O(42)(X)] (X = H(2)O, Br-, Cl-) interlinked by the transition metal complex moieties [M(H(2)N(CH(2))(2)NH(2))(2)] (M = Zn, Cd). These compounds contain an unprecedented complex cation, [M(2)(H(2)N(CH(2))(2)NH(2))(5)](4+). Crystal data for 1: C(9)H(46)N(9)O(26)V(9)Zn(2), monoclinic space group P2(1)/m (No. 11), a = 12.3723(7) A, b = 20.9837(11) A, c = 15.8379(8) A, beta = 97.3320(10) degrees, Z = 4.     

1H NMR, electron paramagnetic resonance, and density functional theory study of dinuclear pentaammineruthenium dicyanamidobenzene complexes

Paramagnetic (1)H NMR and electron paramagnetic resonance (EPR) spectroscopies and density functional theory (DFT) spin density calculations were selectively performed on the [{(NH(3))(5)Ru}(2)(μ-L)](3+,?4+,?5+) complexes, where L is 2,3,5,6-tetrachloro-, 2,5-dichloro-, 2,5-dimethyl-, and unsubstituted 1,4-dicyanamidobenzene dianion, to characterize the electronic structure of these complexes. EPR spectra of the [{(NH(3))(5)Ru}(2)(μ-L)](3+) complexes in N,N'-dimethylformamide at 4 K showed a ruthenium axial signal, and thus the complexes are [Ru(II),L(2-), Ru(III)] mixed-valence systems. DFT spin density calculations of [{(NH(3))(5)Ru}(2)(μ-L)](3+) where L = 1,4-dicyanamidobenzene dianion gave mostly bridging-ligand centered spin distribution for both vacuum and implicit solvent calculations, in poor agreement with EPR, but more realistic results were obtained when explicit electrostatic interactions between solute and solvent were included in modeling. For the [{(NH(3))(5)Ru}(2)(μ-L)](4+) complexes, EPR spectroscopy showed no signal down to 4 K. Nevertheless, solvent-dependent (1)H NMR data and analysis support a [Ru(III),L(2-), Ru(III)] state. Hyperfine coupling constants (A(c)/h) of trans- and cis-ammine and phenyl hydrogens were determined to be 17.2, 3.8, and -1.5 MHz respectively. EPR studies of the [{(NH(3))(5)Ru}(2)(μ-L)](5+) complexes showed a metal-radical axial signal and based on previously published (1)H NMR data, a [Ru(IV),L(2-), Ru(III)] state is favored over a [Ru(III),L(-), Ru(III)] state.     

Formation and reactivity of the cyclometallated N-heterocyclic carbene complexes [Ru(NHC)'(dppe)(CO)H

Thermolysis of [Ru(PPh(3))(dppe)(CO)HCl] (dppe = 1,2-bis(diphenylphosphino)ethane) with the N-heterocyclic carbenes I(i)Pr(2)Me(2) (1,3-diisopropyl-4,5-dimethyl-imidazol-2-ylidene), IEt(2)Me(2) (1,3-diethyl-4,5-dimethyl-imidazol-2-ylidene) or ICy (1,3-dicyclohexylimidazol-2-ylidene) gave the cyclometallated carbene complexes [Ru(NHC)'(dppe)(CO)H] (NHC = I(i)Pr(2)Me(2), 4; IEt(2)Me(2), 5; ICy, 6). Dissolution of 4 in CH(2)Cl(2) or CHCl(3) gave the trans-Cl-Ru-P complex [Ru(I(i)Pr(2)Me(2))'(dppe)(CO)Cl] (7), which converted over hours at room temperature to the trans-Cl-Ru-CO isomer 7'. Chloride abstraction from 7 by NaBPh(4) under an atmosphere of H(2) produced the cationic mono-hydride complex [Ru(I(i)Pr(2)Me(2))(dppe)(CO)H][BPh(4)] (9), which could also be formed by protonating 4 with 1 eq HBF(4)·OEt(2). Treatment of 4 with excess HBF(4)·OEt(2) followed by extraction into MeCN produced the dicationic acetonitrile complex [Ru(I(i)Pr(2)Me(2))(dppe)(CO)(NCMe)(2)][BF(4)](2) (10). The structures of 6, 7, 7' and 10 have been determined by X-ray crystallography.     

Lithiation of tris(alkyl- and arylamido)orthophosphates EP[N(H)R]3 (E = O,S, Se): imido substituent effects and P=E bond cleavage

In the solid state, OP[N(H)Me](3) (1a) and OP[N(H)(t)Bu](3) (1b) have hydrogen-bonded structures that exhibit three-dimensional and one-dimensional arrays, respectively. The lithiation of 1b with 1 equiv of (n)BuLi generates the trimeric monolithiated complex (THF)[LiOP(N(t)Bu)[N(H)(t)Bu](2)](3) (4), whereas reaction with an excess of (n)BuLi produces the dimeric dilithium complex [(THF)(2)Li(2)OP(N(t)Bu)(2)[N(H)(t)Bu]](2) (5). Complex 4 contains a Li(2)O(2) ring in an open-ladder structure, whereas 5 embraces a central Li(2)O(2) ring in a closed-ladder arrangement. Investigations of the lithiation of tris(alkyl or arylamido)thiophosphates, SP[N(H)R](3) (2a, R = (i)Pr; 2b, R = (t)Bu; 2c, R = p-tol) with (n)BuLi reveal interesting imido substituent effects. For the alkyl derivatives, only mono- or dilithiation is observed. In the case of R = (t)Bu, lithiation is accompanied by P-S bond cleavage to give the dilithiated cyclodiphosph(V/V)azane [(THF)(2)Li(2)[((t)BuN)(2)P(micro-N(t)Bu)(2)P(N(t)Bu)(2)]] (9). Trilithiation occurs for the triaryl derivatives EP[N(H)Ar](3) (E = S, Ar = p-tolyl; E = Se, Ar = Ph), as demonstrated by the preparation of [(THF)(4)Li(3)[SP(Np-tol)(3)]](2) (10) and [(THF)(4)Li(3)[SeP(NPh)(3)]](2) (11), which are accompanied by the formation of small amounts of 10.[LiOH(THF)](2) and 11.Li(2)Se(2)(THF)(2), respectively.     

An unprecedented, reversible coordination mode rearrangement: eta3(B-H) vs.eta1(Sn) stanna-closo-dodecaborate coordination

The synthesis of the ruthenium stanna-closo-dodecaborate complex [Bu(3)MeN](2)[Ru(dppb)(MeCN)(2)(SnB(11)H(11))(2)] by an unprecedented, reversible eta(3)(B-H) to eta(1)(Sn) rearrangement of [Bu(3)MeN](2)[Ru(dppb)(SnB(11)H(11))(2)] is described and the product is characterized by multinuclear NMR spectroscopy and single-crystal X-ray diffraction.     

Effects of phosphine ligand chelation on the reactivity of monomeric parent amido ruthenium complexes: synthesis and reactivity of such a complex bearing monodentate ligands

The parent amido complex cis-(PMe(3))(4)Ru(H)(NH(2)) (2) has been prepared via the deprotonation of [cis-(PMe(3))(4)Ru(H)(NH(3))(+)][BPh(4)(-)]. The amido complex is a somewhat weaker base than the DMPE analogue trans-(DMPE)(2)Ru(H)(NH(2)) but is still basic enough to quantitatively deprotonate fluorene and reversibly deprotonate 1,3-cyclohexadiene and toluene. Complex 2 exhibits very labile phosphine ligands, two of which can be replaced by DMPE to yield the mixed complex cis-(PMe(3))(2)(DMPE)Ru(H)(NH(2)). Because of the ligand lability, 2 also undergoes hydrogenolysis and rapid exchange with labeled NH(3). The amide complex reacts with alkyl halides to yield E2 and S(N)2 products, along with ruthenium hydrido halide complexes including the ruthenium fluoride cis-(PMe(3))(4)Ru(H)(F). Ruthenium hydrido ammonia halide ion pair intermediates [cis-(PMe(3))(4)Ru(H)(NH(3))(+)][X(-)] are observed in some deprotonation and E2 reactions, and measurement of the equilibrium constants for NH(3) displacement from these complexes suggests that they benefit from significant hydrogen bonding between X(-) and NH(3) groups. Cumulenes also react with complex 2 to afford the products of insertion into an NH bond. The rates of neither these NH insertion reactions nor the reversible deprotonation reactions show any dependence on the concentration of PMe(3) present, suggesting that these reactions take place directly at the NH(2) group and do not involve precoordination of substrate to the metal center.     

Iridium derivatives of fluorinated aromatics by C-H activation: isolation of classical and non-classical hydrides

A reaction of trans-[Ir(H)(5)(PiPr(3))(2)] (1) with 2,3,5,6-tetrafluoropyridine, pentafluorobenzene or 1,3-difluorobenzene in the presence of neohexene affords the square-pyramidal C-H activation products cis-trans-[Ir(4-C(5)NF(4))(H)(2)(PiPr(3))(2)] (2), cis-trans-[Ir(C(6)F(5))(H)(2)(PiPr(3))(2)] (4) and cis-trans-[Ir(2-C(6)H(3)F(2))(H)(2)(PiPr(3))(2)] (6). Irradiation of complex 1 with 2,3,5,6-tetrafluoropyridine or pentafluorobenzene gave the hydrides cis-trans-[Ir(4-C(5)NF(4))(H)(2)(H(2))(PiPr(3))(2)] (3) or cis-trans-[Ir(C(6)F(5))(H)(2)(H(2))(PiPr(3))(2)] (5). The presence of non-classical bound H(2) moieties has been demonstrated by the measurement of T(1) times at different temperatures. For 3 the H-H distance in the H(2) ligand can be estimated to be 0.82 A. The dihydride compounds 2, 4 and 6 react with CO to yield the complexes cis-trans-[Ir(Ar)(H)(2)(CO)(PiPr(3))(2)] (7: Ar = 4-C(5)NF(4), 8: Ar = C(6)F(5), 9: Ar = 2-C(6)H(3)F(2)). A reaction of 2 or 3 with an excess of ethylene leads to the formation of ethane and the Ir(i) ethylene complex trans-[Ir(4-C(5)NF(4))(eta(2)-C(2)H(4))(PiPr(3))(2)] (10). Treatment of 10 with CO furnishes the Ir(i) complex trans-[Ir(4-C(5)NF(4))(CO)(PiPr(3))(2)] (11).     

Preparation and properties of the aqua ions [W(4)S(4)(H(2)O)(12)](n+) (n = 5, 6) and crystal structure of (Me(2)NH(2))(6)[W(4)S(4)(NCS)(12)].0.5H(2)O

The [3 + 1] reaction of [W(3)S(4)(H(2)O)(9)](4+) with [W(CO)(6)] in 2 M HCl under hydrothermal conditions (130 degrees C) gives the [W(4)S(4)(H(2)O)(12)](6+) cuboidal cluster, reduction potential 35 mV vs NHE (6+/5+ couple). The reduced form is obtained by controlled potential electrolysis. X-ray crystal structure was determined for (Me(2)NH(2))(6)[W(4)S(4)(NCS)(12)].0.5H(2)O. The W-W and W-S bond lengths are 2.840 and 2.379 A, respectively.     

Unusual pathways for metal-assisted C[bond]C and C[bond]P coupling reactions using allenylidenerhodium complexes as precursors

The rhodium allenylidenes trans-[RhCl[[double bond]C[double bond]C[double bond]C(Ph)R](PiPr(3))(2)] [R = Ph (1), p-Tol (2)] react with NaC(5)H(5) to give the half-sandwich type complexes [(eta(5)-C(5)H(5))Rh[[double bond]C[double bond]C[double bond]C(Ph)R](PiPr(3))] (3, 4). The reaction of 1 with the Grignard reagent CH(2)[double bond]CHMgBr affords the eta(3)-pentatrienyl compound [Rh(eta(3)-CH(2)CHC[double bond]C[double bond]CPh(2))(PiPr(3))(2)] (6), which in the presence of CO rearranges to the eta(1)-pentatrienyl derivative trans-[Rh[eta(1)-C(CH[double bond]CH(2))[double bond]C[double bond]CPh(2)](CO)(PiPr(3))(2)] (7). Treatment of 7 with acetic acid generates the vinylallene CH(2)[double bond]CH[bond]CH[double bond]=C=CPh(2) (8). Compounds 1 and 2 react with HCl to give the five-coordinate allenylrhodium(III) complexes [RhCl(2)[CH[double bond]C[double bond]C(Ph)R](PiPr(3))(2)] (10, 11). An unusual [C(3) + C(2) + P] coupling process takes place upon treatment of 1 with terminal alkynes HC[triple bond]CR', leading to the formation of the eta(3)-allylic compounds [RhCl[eta(3)-anti-CH(PiPr(3))C(R')C[double bond]C[double bond]CPh(2)](PiPr(3))] [R' = Ph (12), p-Tol (13), SiMe(3) (14)]. From 12 and RMgBr the corresponding phenyl and vinyl rhodium(I) derivatives 15 and 16 have been obtained. The previously unknown unsaturated ylide iPr(3)PCHC(Ph)[double bond]C[double bond]C[double bond]CPh(2) (17) was generated from 12 and CO. A [C(3) + P] coupling process occurs on treatment of the rhodium allenylidenes 1, 2, and trans-[RhCl[[double bond]C[double bond]C[double bond]C(p-Anis)(2)](PiPr(3))(2)] (20) with either Cl(2) or PhICl(2), affording the ylide-rhodium(III) complexes [RhCl(3)[C(PiPr(3))C[double bond]C(R)R'](PiPr(3))] (21-23). The butatrienerhodium(I) compounds trans-[RhCl[eta(2)-H(2)C[double bond]C[double bond]C[double bond]C(R)R'](PiPr(3))(2)] (28-31) were prepared from 1, 20, and trans-[RhCl[[double bond]C[double bond]C[double bond]C(Ph)R](PiPr(3))(2)] [R = CF(3) (26), tBu (27)] and diazomethane; with the exception of 30 (R = CF(3), R' = Ph), they thermally rearrange to the isomers trans-[RhCl[eta(2)-H(2)C[double bond]C[double bond]C[double bond]C(R)R'](PiPr(3))(2)] (32, 33, and syn/anti-34). The new 1,1-disubstituted butatriene H(2)C[double bond]C[double bond]C[double bond]C(tBu)Ph (35) was generated either from 31 or 34 and CO. The iodo derivatives trans-[RhI(eta(2)-H(2)C[double bond]C[double bond]C[double bond]CR(2))(PiPr(3))(2)] [R = Ph (38), p-Anis (39)] were obtained by an unusual route from 1 or 20 and CH(3)I in the presence of KI. While the hydrogenation of 1 and 26 leads to the allenerhodium(I) complexes trans-[RhCl[eta(2)-H(2)C[double bond]C[double bond]C(Ph)R](PiPr(3))(2)] (40, 41), the thermolysis of 1 and 20 produces the rhodium(I) hexapentaenes trans-[RhCl(eta(2)-R(2)C[double bond]C[double bond]C[double bond]C[double bond]C[double bond]CR(2))(PiPr(3))(2)] (44, 45) via C-C coupling. The molecular structures of 3, 7, 12, 21, and 28 have been determined by X-ray crystallography.     

A phosphorus supported multisite coordinating tris hydrazone P(S)[N(Me)N=CH-C6H4-o-OH]3 as an efficient ligand for the assembly of trinuclear metal complexes: synthesis, structure, and magnetism

A phosphorus supported multisite coordinating ligand P(S)[N(Me)N=CH-C(6)H(4)-o-OH](3) (2) was prepared by the condensation of the phosphorus tris hydrazide P(S)[N(Me)NH(2)](3) (1) with o-hydroxybenzaldehyde. The reaction of 2 with M(OAc)(2).xH(2)O (M = Mn, Co, Ni, x = 4; M = Zn, x = 2) afforded neutral trinuclear complexes [P(S)[N(Me)N=CH-C(6)H(4)-o-O](3)](2)M(3) [M = Mn (3), Co (4), Ni (5), and Zn (6)]. The X-ray crystal structures of compounds 2-6 have been determined. The structures of 3-6 reveal that the trinculear metal assemblies are nearly linear. The two terminal metal ions in a given assembly have an N(3)O(3) ligand environment in a distorted octahedral geometry while the central metal ion has an O(6) ligand environment also in a slightly distorted octahedral geometry. In all the complexes, ligand 2 coordinates to the metal ions through three imino nitrogens and three phenolate oxygens; the latter act as bridging ligands to connect the terminal and central metal ions. The compounds 2-6 also show intermolecular C-H...S=P contacts in the solid-state which lead to the formation of polymeric supramolecular architectures. The observed magnetic data for the (s = 5/2)3 L(2)(Mn(II))(3) derivative, 3, show an antiferromagnetic nearest- and next-nearest-neighbor exchange (J = -4.0 K and J' = -0.15 K; using the spin Hamiltonian H(HDvV) = -2J(S(1)S(2) + S(2)S(3)) - 2J'S(1)S(3)). In contrast, the (s = 1)(3) L(2)(Ni(II))(3) derivative, 5, displays ferromagnetic nearest-neighbor and antiferromagnetic next-nearest-neighbor exchange interactions (J = 4.43 K and J' = -0.28 K; H = H(HDvV)+ S(1)DS(1) + S(2)DS(2)+ S(3)DS(3)). The magnetic behavior of the L(2)(Co(II))(3) derivative, 4, reveals only antiferromagnetic exchange analogous to 3 (J = -4.5, J' = -1.4; same Hamiltonian as for 3).