Alpha-amino acids with metallocenyl side chains

A straightforward method for the synthesis of enantiomerically pure bis(valine)metallocenes is presented. Derivatives of lithium cyclopentadienylvaline 1a, b were obtained by addition of the (R)- or (S)-Sch?llkopf reagents to 6,6-dimethylfulvene as single enantiomers and gave with FeCl2 or [RuCl2(dmso)4] the chiral metallocenes [Fe[C5H4-CMe2-[C4H2N2(OMe)2iPr]]2] (2a, b) and [Ru[C5H4-CMe2-[C4H2N2(OMe)2iPr]]2] (3a, b). Complex 2b was hydrolyzed to the ferrocenylene-bis(valine-methylester) [[Fe[C5H4-CMe2-CH(NH3+)COOMe]2]2+(Cl-)2] (7) without racemization. Complex 7 could be used as ligand and was treated with [[Cp*IrCl2]2] to afford [Fe[C5H4-CMe2-CH(COOMe)(NH2-IrCp*Cl2)]2] (10). The reactions of 1 with CoCl2, [Re(CO)5Br], [[(cod)RhCl2]2] (cod= 1,5-cyclooctadiene) or [Cp*MCl3] (M= Ti, Zr) gave the cyclopentadienyl complexes [[Co[C5H4-CMe2-[C4H2N2(OMe)2iPr]]2]+ I-] (11) and [Re[C5H4-CMe2-[C4H2N2(OMe)2iPr]](CO)3] (13), [(C8H12)Rh[C5H4-CMe2-[C4H2N2(OMe)2(iPr)]]] (14). [[Rh[C5H4-CMe2-[C4H2N2(OMe)2(iPr)]]I]2(mu-I)2] (15), [Cp*Cl2Ti-[C5H4-CMe2-[C4H2N2(OMe)2(iPr)]]] (16), and [Cp*Cl2Zr[C5H4-CMe2-[C4H2N2(OMe)2(iPr)]]] (17), with chiral valine derivatives as substituents on the cyclopentadienyl ring and with excellent diastereoselectivities. Also the Seebach reagent (Boc-BMI) or O'Donnell reagent could be added to 6,6-dimethylfulvene to give the lithium cyclopentadienides Li[C5H4-CMe2-[C3H2(tBu)(N-Boc)(NMe)O]] (18) and Li[C5H4-CMe2-CH(NCPh2)(COOEt)] (21), which formed the ferrocene derivatives [Fe[C5H4-CMe2-[C3H2(tBu)(N-Boc)(NMe)O]]2] (19) and [Fe[C5H4-CMe2-CH(NCPh2)(COOEt)]2] (22). The stable cobaltocinium cation in 11 and the complex 19 could be hydrolyzed to the metallocenes 12 and [Fe(C5H4-CMe2-CH(NH3+)(COO-)]2] (20) with two valines in the 1,1'-position. The structures of 2a, b, 11, 15, and 16 were determined by X-ray diffraction and confirm the diastereomeric purity of the compounds.     

Solution and solid-state preparation of 18-crown[6] complexes with M[HSO4]n salts (M = NH4+, K+, Sr2+ and n = 1, 2) and an investigation of solvation/desolvation processes and crystal polymorphism

18-Crown[6] ether has been used to prepare a new class of organic-inorganic complexes of general formula 18-crown[6]M[HSO(4)](n) (where M = NH(4) (+), K(+), Sr(2+) and n = 1, 2) by reacting directly in solution or in the solid state the crown ether 18-crown[6] with inorganic salts such as [NH(4)][HSO(4)], K[HSO(4)], and Sr[HSO(4)](2). The structures of 18-crown[6][NH(4)][HSO(4)]2 H(2)O (12 H(2)O), 18-crown[6][NH(4)][HSO(4)] (1), 18-crown[6]K[HSO(4)]2 H(2)O (22 H(2)O), 18-crown[6]K[HSO(4)] (2), and 18-crown[6]Sr[HSO(4)](2) (3) have been characterized by single-crystal X-ray diffraction. The reversible water loss in compounds 12 H(2)O and 22 H(2)O leads to formation of the corresponding anhydrous phases 18-crown[6][NH(4)][HSO(4)] (1), and 18-crown[6]K[HSO(4)] (2), which undergo, on further heating, enantiotropic solid-solid transitions very likely associated with the on-set of a solid state dynamical process. Similar high-temperature behavior is shown by 18-crown[6]Sr[HSO(4)](2) (3). The dehydration and phase-transition processes have been investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and variable temperature X-ray powder diffraction.     

Further study of the reaction of Fe2+ with CN-: synthesis and characterization of cis and trans [FeII,III(CN)4L2]n- complexes

The reaction of Fe2+ with CN-, which was first performed in 1704, has been used to synthesize a new series of basic [FeII,III(CN)4L2]n- complexes, where L is a monodentate ligand. trans-Na2[FeII(CN)4(DMSO)2] and cis-[NEt4]2[FeII(CN)4(pyridine)2] are synthesized by the direct reaction of FeCl2 with 4 equiv of CN- in DMSO or pyridine. Air oxidation of the latter compound gives cis-[NEt4][FeIII(CN)4(pyridine)2]. The non-cyanide ligands in these complexes undergo facile ligand exchange reactions with solvent. Reaction of cis-[NEt4]2[FeII(CN)4(pyridine)2] with CO at room temperature gives trans-[NEt4]2[FeII(CN)4(pyridine)(CO)].     

A family of oxo-chalcogenide molybdenum and tungsten complexes, (n-Bu4N)2[M2O2(mu-Q)2(1,3-dithiole-2-thione-4,5-dithiolate)2] (M = Mo, W; Q = S, Se): new synthetic entries, structure, and gas-phase behavior

A new series of complexes with the general formula (n-Bu4N)2[M2O2(micro-Q)2(dmit)2] (where M = Mo, W; Q = S, Se; dmit = 1,3-dithiole-2-thione-4,5-dithiolate) have been prepared. Fragmentation of the trinuclear cluster (n-Bu4N)2[Mo3(micro3-S)(micro-S2)3(dmit)3] in the presence of triphenylphosphine (PPh3) gives the dinuclear compound (n-Bu4N)2[Mo2O2(micro-S)2(dmit)2] [(n-Bu4N)2[2]], which is formed via oxidation in air from the intermediate (n-Bu4N)2[Mo3(micro3-S)(micro-S)3(dmit)3] [(n-Bu4N)2[1]] complex. Ligand substitution of the molybdenum sulfur bridged [Mo2O2(micro-S)2(dimethylformamide)6]2+ dimer with the sodium salt of the dmit dithiolate also affords the dianionic compound (n-Bu4N)2[2]. The whole series, (n-Bu4N)2[Mo2O2(micro-Se)2(dmit)2] [(n-Bu4N)2[3]], (n-Bu4N)2[W2O2(micro-S)2(dmit)2] [(n-Bu4N)2[4]], (n-Bu4N)2[W2O2(micro-Se)2(dmit)2] [(n-Bu4N)2[5]], and (n-Bu4N)2[Mo2O2(micro-S)2(dmid)2] [(n-Bu4N)2[6]; dmid = 1,3-dithiole-2-one-4,5-dithiolate], has been synthesized by the excision of the polymeric (Mo3Q7Br4)x phases with PPh3 or 1,2-bis(diphenylphosphanyl)ethane in acetonitrile followed by the dithiolene incorporation and further degradation in air. Direct evidence of the presence of the intermediates with the formula [M3Q4(dmit)3]2- (M = Mo, W; Q = S, Se) has been obtained by electrospray ionization mass spectrometry. The crystal structures of (n-Bu4N)2[1], (PPh4)2[Mo2O2(micro-S)2(dmit)2] [(PPh4)2[2]; PPh4 = tetraphenylphosphonium], (n-Bu4N)2[2], (n-Bu4N)2[4], (PPh4)2[W2O2(micro-Se)2(dmit)2] [(PPh4)2[5]], and (n-Bu4N)2[6] have been determined. A detailed study of the gas-phase behavior for compounds (n-Bu4N)2[2-6] shows an identical fragmentation pathway for the whole family that consists of a partial breaking of the two dithiolene ligands followed by the dissociation of the dinuclear cluster.     

Preparation of mononuclear tungsten tris(sulfido) and molybdenum sulfido-tetrasulfido complexes with hydridotris(pyrazolyl)borate coligand and conversion of the former into sulfido-bridged bimetallic complex having Pt(mu-S)2WS core

Treatment of [Et4N][(Me2Tp)W(CO)3] (Me2Tp = HB(3,5-dimethylpyrazol-1-yl)3) with S8 in DMF at room temperature afforded a tris(sulfido) complex [Et4N][(Me2Tp)WS3] (1a), while that of [Et4N][TpW(CO)3] (Tp = HB(pyrazol-1-yl)3) in MeCN resulted in the formation of [Et4N][TpWS3] (1b) along with [Et4N]2[[WO(S2)2]2(mu-S)] (6) as a byproduct. Under similar conditions, [Et4N][(Me2Tp)Mo(CO)3] gave a mixture of a sulfido-tetrasulfido complex [Et4N][(Me2Tp)MoS(S4)] (2a) and its monooxo analogue [Et4N][(Me2Tp)MoO(S4)], although a sulfido-tetrasulfido complex [Et4N][TpMoS(S4)] (2b) was exclusively obtained from [Et4N][TpMo(CO)3]. The reaction of 1a with [PtCl2(cod)] (cod = 1,5-cyclooctadiene) in MeCN at room temperature led to the formation of a sulfido-bridged mixed-metal complex [Et4N][(Me2Tp)WS(mu-S)2PtCl2] (10). The structures of new complexes have been determined in detail by the X-ray analyses for 1a.MeCN, 1b, 2a, 2b, 6, and 10.     

Homoleptic cobalt and copper phenolate A2[M(OAr)4] compounds: the effect of phenoxide fluorination

Two series of homoleptic phenolate complexes with fluorinated aryloxide ligands A2[M(OAr)4] with M=Co2+ or Cu2+, OAr-=(OC6F5)- (OArF) or [3,5-OC6H3(CF3)2]- (OAr'), A+=K (18-crown-6)+, Tl+, Ph4P+, Et3HN+, or Me4N+ have been synthesized. Two related complexes with nonfluorinated phenoxide ligands have been synthesized and studied in comparison to the fluorinated aryloxides demonstrating the dramatic structural changes effected by modification of OPh to OAr(F). The compounds [K(18-crown-6)]2[Cu(OArF)4], 1a; [K(18-crown-6)]2[Cu(OAr')4], 1b; [Tl2Cu(OArF)4], 2a; [Tl2Cu(OAr')4], 2b; (Ph4P)2[Cu(OArF)4], 3; (nBu4N)2[Cu(OArF)4], 4; (HEt3N)2[Cu(OArF)4], 5; [K(18-crown-6)]2[Cu2(mu2-OC6H5)2(OC6H5)4], 6; [K(18-crown-6)]2[Co(OArF)4], 7a; [(18-crown-6)]2[Co(OAr')4], 7b; [Tl2Co(OArF)4], 8a; [Tl2Co(OAr')4], 8b; (Me4N)2[Co(OArF)4], 9; [Cp2Co]2[Co(OAr')4], 10; and [(18-crown-6)])[Co2(mu2-OC6H5)2(OC6H5)4], 11, have been characterized with UV-vis and multinuclear NMR spectroscopy and solution magnetic moment studies. Cyclic voltammetry was used to study 1a, 1b, 7a, and 7b. X-ray crystallography was used to characterize 1b, 3, 4, 5, 6, 7a, 7b, 10, and 11. The related [MX4]2- compound (Ph4P)2[Co(OArF)2Cl2], 12, has also been synthesized and characterized spectroscopically, as well as with conductivity and single-crystal X-ray diffraction. Use of fluorinated aryloxides permits synthesis and isolation of the mononuclear, homoleptic phenolate anions in good yield without oligomerized side products. The reaction conditions that result in homoleptic 1a and 7a with OArF upon changing the ligand to OPh result in mu2-OPh bridging phenoxides and the dimeric complexes 6 and 11. The [M(OArF)4]2- and [M(OAr')4]2- anions in 1a, 1b, 3, 4, 5, 7a, 7b, 9, and 10 demonstrate that stable, isolable homoleptic phenolate anions do not need to be coordinatively or sterically saturated and can be achieved by increasing the electronegativity of the ligand.     

Hybrid molecular material exhibiting single-molecule magnet behavior and molecular conductivity

Two unique materials based on Mn4 single-molecule magnet (SMM) clusters (ST=9) and integer or non-integer average valent platinum maleonitriledithiolate (mnt2-) complexes, [{MnII2MnIII2(hmp)6(MeCN)2}{Pt(mnt)2}2][Pt(mnt)2]2.2MeCN (1) and [{MnII2MnIII2(hmp)6(MeCN)2}{Pt(mnt)2}4][Pt(mnt)2]2 (2), were synthesized by the material diffusion method and electrochemical oxidation, respectively (hmp-=2-hydroxymethylpyridinate). 1 and 2 are comprised of four and six [Pt(mnt)2]n- units, respectively, in addition to a common MnII2MnIII2 double-cuboidal unit, [MnII2MnIII2(hmp)6(MeCN)2]4+ (hereinafter [Mn4]4+). Among the [Pt(mnt)2]n- units, two units in 1 and four units in 2 are coordinated with the [Mn4]4+ unit, forming a 1D chain of {-[Mn4]-[Pt(mnt)2]2-} for 1 and a discrete subunit of {[Pt(mnt)2]2-[Mn4]-[Pt(mnt)2]2} for 2. The other two [Pt(mnt)2]n- units, occupying void space of the packing, form a stacking column with the coordinating [Pt(mnt)2]n- units, finally constructing hybrid frames of aggregates consisting of [Mn4]4+ units and [Pt(mnt)2]n- units. Electronic conductivity measurements revealed that 1 is an insulator and 2 is a semiconductor with sigma=0.22 S.cm(-1) at room temperature and an activation energy of 136 meV. Detailed magnetic measurements proved that the [Mn4]4+ units in 1 and 2 behave as SMMs with an ST=9 ground state at low temperatures. There is no significant interaction between [Mn4]4+ units and [Pt(mnt)2]n- units, but interactions between localized spins of [Pt(mnt)2]n- were detected even in 2 at low temperatures where the conductivity is electronically insulated. 2 is the first example of a hybridized material exhibiting SMM behavior and electronic conductivity.     

Mechanistic studies on the reactions of PhS(-) or [MoS(4)](2)(-) with [M(4)(SPh)(10)](2)(-) (M = Fe or Co)

Kinetic studies, using stopped-flow spectrophotometry, on the reactions of [M(4)(SPh)(10)](2)(-) (M = Fe or Co) with PhS(-) to form [M(SPh)(4)](2)(-) are described, as are the reactions between [M(4)(SPh)(10)](2)(-) and [MoS(4)](2)(-) to form [S(2)MoS(2)Fe(SPh)(2)](2)(-) or [S(2)MoS(2)CoS(2)MoS(2)](2)(-). The kinetics of the reactions with PhS(-) are consistent with an initial associative substitution mechanism involving attack of PhS(-) at one of the tetrahedral M sites of [M(4)(SPh)(10)](2)(-) to form [M(4)(SPh)(11)](3)(-). Subsequent or concomitant cleavage of a micro-SPh ligand, at the same M, initiates a cascade of rapid reactions which result ultimately in the complete rupture of the cluster and formation of [M(SPh)(4)](2)(-). The kinetics of the reaction between [M(4)(SPh)(10)](2)(-) and [MoS(4)](2)(-) indicate an initial dissociative substitution mechanism at low concentrations of [MoS(4)](2)(-), in which rate-limiting dissociation of a terminal thiolate from [M(4)(SPh)(10)](2)(-) produces [M(4)(SPh)(9)](-) and the coordinatively unsaturated M site is rapidly attacked by a sulfido group of [MoS(4)](2)(-). It is proposed that subsequent chelation of the MoS(4) ligand results in cleavage of an M-micro-SPh bond, initiating a cascade of reactions which lead to the ultimate break-up of the cluster and formation of the products, [S(2)MoS(2)Fe(SPh)(2)](2)(-) or [S(2)MoS(2)CoS(2)MoS(2)](2)(-). With [Co(4)(SPh)(10)](2)(-), at higher concentrations of [MoS(4)](2)(-), a further substitution pathway is evident which exhibits a second order dependence on the concentration of [MoS(4)](2)(-). The mechanistic picture of cluster disruption which emerges from these studies rationalizes the "all or nothing" reactivity of [M(4)(SPh)(10)](2)(-).     

Cation and anion diversity in [M(dithiooxalate)2]2- salts: structure robustness in crystal synthesis

A series of crystalline salts based on the [M(dto)2]2- (dto = 1,2-dithiooxalate, M = Ni, Pt, Cu) dianion with hydrogen-bond donor cations have been synthesised following a molecular tectonics approach. The chelating M(dto)[dot dot dot]HN supramolecular synthon has been exploited in a systematic study of its robustness. The effects of competition between hydrogen-bond acceptors, of the shape and functionality of the cations and of varying the metal in the anion are discussed. The preparation and structural characterisation of the new crystalline phases [4,4'-H(2)bipy][Pt(dto)2] (2), [HNC5H4CO2H-4]2[Pt(dto)2] (5), [HNC5H4CO2H-3]2[Pt(dto)2] (6), [HNC5H4CH2CO2H-4]2[Ni(dto)2] (7), [HNC(5)H(4)CH(2)CO(2)H-3]2[Ni(dto)2] (8), [HNC5H4CONH2-4]2[Ni(dto)2] (9), [HNC5H4CHNOH-4]2[Ni(dto)2] (10), [HNC5H4CHNOH-3]2[Ni(dto)2] (11), [4,4'-H2bipip][Ni(dto)2] (12), [H2NC5H9CO2H-4]2[Pt(dto)2] (12), [H2NC5H9CO2H-4]2[Cu(dto)2] (14), [H2NC5H9CO2H-3]2[Ni(dto)2][H2O]2 (15), [H2NC5H9CO2H-3]2[Pt(dto)2][H2O]2 (16), [H2NC5H9CO2H-3]2[Cu(dto)2][H2O]2 (17), [H(Me)NC5H9CO2H-4]2[Ni(dto)2][H2O]2 (18) is reported. The charge-assisted NH[dot dot dot]dto synthon is formed in each of compounds 1-20, and is apparently much more robust than the conventional synthons used (such as the carboxylic acid dimer), which have a much lower rate of occurrence. The NH[dot dot dot]dto synthon may be generalised to 3- and 4-pyridinium species and 3- and 4-piperidinium derivatives. In the latter cases branching of the hydrogen-bond networks through the NH2 groups arises. The robustness of the NH...dto synthon allows structures of the form [NH cation]2[M(dto)2] to be regarded as being formed by the packing of neutral supermolecules. Cases of isomorphism (as in 16-18) and latent polymorphism (e.g. in 4 and 6) are noted.     

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.     

Helical complexes containing diamide-bridged benzene-o-dithiolato/catecholato ligands

The benzene-o-dithiol/catechol ligands H4-2 and H4-3 react with [TiO(acac)2] to give the dinuclear, double-stranded anionic complexes [Ti2(L)2(mu-OCH3)2](2-) ([22](2-), L=2(4-); [23](2-), L=3(4-)). NMR spectroscopic investigations reveal that the complex anion [Ti2(2)2(mu-OCH3)(2)](2-) is formed as a mixture of three of four possible isomers/pairs of enantiomers, whereas only one isomer of the complex anion [Ti2(3)2(mu-OCH3)(2)](2-) is obtained. The crystal structure analysis of (PNP)2[Ti2(3)2(mu-OCH3)2] shows a parallel orientation of the ligand strands, whereas the structure determination for (AsPh4)2[Ti2(2)2(mu-OCH3)2] does not yield conclusive results about the orientation of the ligand strands due the presence of different isomers in solution, the possible co-crystallisation of different isomers and severe disorder in the crystal. NMR spectroscopy shows that ligand H4-3 reacts at elevated temperature with [TiO(acac)2] to give the triple-stranded helicate (PNP)4[Ti2(3)3] ((PNP)4[24]) as a mixture of two isomers, one with a parallel orientation of the ligand strands and one with an antiparallel orientation. Exclusively the triple-stranded helicates [Ti2(L)(3)](4-) ([25](4-), L=1(4-); [26](2-), L=4(4-)) are formed in the reaction of ligands H4-1 and H4-4 with [TiO(acac)2]. The molecular structures of Na(PNP)3[Ti2(1)3]CH(3)OHH(2)OEt(2)O (Na(PNP)3[25]CH(3)OHH(2)OEt(2)O) and Na(1.5)(PNP)(6.5)[Ti2(4)3]2.3 DMF (Na(1.5)(PNP)(6.5)[26]2.3 DMF) reveal a parallel orientation of the ligand strands in both complexes, which is retained in solution. The sodium cations present in the crystal structures lead to two different kinds of aggregation in the solid state. Na-[25]-Na-[25]-Na polymeric chains are formed from compound Na(PNP)3[25], with the sodium cations coordinated by the carbonyl groups of two ligand strands from two different [Ti2(1)3](4-) ions in addition to solvent molecules. In contrast to this, two [Ti2(4)3](4-) ions are connected by a sodium cation that is coordinated by the three meta oxygen atoms of the catecholato groups of each complex tetraanion to form a central {NaO6} octahedron in the anionic pentanuclear complex {[26]-Na-[26]}(7-).     

Mononuclear (Pd, Pt), heterodinuclear (PdAg, PtAg), and tetranuclear (Pd2Ag2, Pt2Ag2) 1,1-ethylenedithiolato complexes

lp;&-5q;1 The reactions of [Tl2[S2C=C[C(O)Me]2]]n with [MCl2L2] (1:1) or with [MCl2(NCPh)2] and PPh3 (1:1:2) give complexes [M[eta2-S2C=C[C(O)Me]2]L2] [M = Pt, L2 = 1,5-cyclooctadiene (cod) (1); L2 = bpy, M = Pd (2a), Pt (2b), L = PPh3, M = Pd (3a), Pt (3b)] whereas with MCl2 and QCl (2:1:2) anionic derivatives Q2[M[eta2-S2C=C[C(O)Me]2]2] [M = Pd, Q = NMe4 (4a), Ph3P=N=PPh3 (PPN) (4a'), M = Pt, Q = NMe4 (4b)] are produced. Complexes 1 and 3 react with AgClO4 (1:1) to give tetranuclear complexes [[ML2]2Ag2[mu2,eta2-(S,S')-[S2C=C[C(O)Me]2]2]](ClO4)2 [L = PPh3, M = Pd (5a), Pt (5b), L2 = cod, M = Pt (5b')], while the reactions of 3 with AgClO4 and PPh3 (1:1:2) give dinuclear [[M(PPh3)2][Ag(PPh3)2][mu2,eta2-(S,S')-S2C=C[C(O)Me]2]]]ClO4 [M = Pd (6a), Pt (6b)]. The crystal structures of 3a, 3b, 4a, and two crystal forms of 5b have been determined. The two crystal forms of 5b display two [Pt(PPh3)2][mu2,eta2-(S,S')-[S2C=C[C(O)Me]2]2] moieties bridging two Ag(I) centers.     

Hydrogen-bonded networks through second-sphere coordination

The reaction of 4, 7-phenanthroline (1) with aqueous transitionmetal complexes [Mn(H2O)6][NO3]2, [Co(H2O)6][NO3]2, [Ni(H2O)6[NO3]2, [Mn(H2O)6][ClO4]2, and [Co(H2O)6][ClO4]2 does not produce coordination complexes between these metal cations and the N-donor ligand as expected. Instead, supramolecular hydrogenbonded networks are formed between the nitrogen donor atoms of 4, 7-phenanthroline and the OH groups of coordinated water molecules: M-O-H...N interactions. This motif of second-sphere coordination for 1 can be exploited as a tool for crystal engineering. As a demonstration of the generality of this new interaction as a supramolecular building block, five X-ray crystal structures are reported that utilise this hydrogen bonding scheme; [Co(H2O)4(NO3)2].(1)2 (2a), [Co(MeCN)2(H2O)4][ClO4]2.(1)2 (2b), [Ni(H2O)4(NO3)2].(1)2 (3a), [Mn(H2O)4(NO3)2].(1)2 (4a), and [Mn(H2O)6][ClO4]2.(1)(4).4H2O (4b). Each network involves complete saturation of the hydrogen-bond donor sets between the aqua complex and 1 using primarily M-O-H...N(1) and M-O-H...O(anion), interactions. Thermogravimteric analysis shows these materials to have stabililities similar to coordination polymers involving metal-ligand bonds; this demonstrates that second-sphere hydrogen bonding has potential for the construction of polymeric metal-containing materials.     

Syntheses and reactivity studies of solvated dirhenium acetonitrile complexes

Fully and partially solvated triply-bonded [Re2]4+ complexes have been synthesized and their X-ray structures are described. A fully solvated dirhenium salt with BArf [tetrakis(3,5-bis(trifluoromethyl)phenyl)borate] as the counter anion [Re2(CH3CN)10][BArf]4 () has been characterized. The solubility of the complex in CH2Cl2 and THF in addition to CH3CN offers the possibility of improved reactivity. The structure of [Re2(micro-O)(CH3CN)10][BF4]4 () that possesses a linear [Re(III)-O-Re(III)]4+ unit is reported. Protonation reactions of cis-Re2Cl2(dppm)2(O2CCH3)2 and trans-Re2Cl4(dppm)2 with HBF4.Et2O in acetonitrile afforded cis and trans [Re2(dppm)2(CH3CN)6][BF4]4 ( and ), respectively. Prolonging the reaction time, however, does not lead to fully solvated complex [Re2(CH3CN)10][BF4]4. The neutral nitrogen donor ligands pynp (2-(2-pyridyl)-1,8-naphthyridine) and tznp (2-(2-thiazolyl)-1,8-naphthyridine) react readily with [Re2(CH3CN)10][BF4]4 to provide trans-[Re2(pynp)2(CH3CN)4][BF4]4 and trans-[Re2(tznp)2(CH3CN)4][BF4]4. The X-ray structures trans-[Re2(pynp)2(CH3CN)4][BF4]4 () and trans-[Re2(tznp)2(CH3CN)4][BF4]3[PF6] () have been determined.     

Transition Metal Complexes of Cyanoisocyanoarenes as Building Blocks for One-, Two-, and Three-Dimensional Molecular Solids

The complexes trans-[MI(2)(CNC(6)H(4)-CN-4)(2)], (M = Pd and Pt), trans-[FeI(2)L(4)] (L = CNC(6)H(4)-CN-4 and CNC(6)H(2)-Me(2)-2,6-CN-4), and [Mn(CNC(6)H(4)-CN-4)(6)][SO(3)CF(3)] were prepared. The compounds are thermally stable up to 230 degrees C or higher. The molecular structure of trans-[FeI(2)(CNC(6)H(4)-CN-4)(4)] was determined by X-ray crystallography: monoclinic, space group P2(1)/n, a = 11.570(2) ?, b = 10.1052(8) ?, c = 28.138(7) ?, beta = 92.034(9) degrees, Z = 4, 3464 unique reflections, R = 0.074, R(w) = 0.089. The complexes contain the peripheral cyano groups in linear, planar, and octahedral dispositions, respectively. Solids were obtained by combining solutions of [PdI(2)(CNC(6)H(4)-CN-4)(2)] and [Cu(hfacac)(2)], [FeI(2)(CNC(6)H(4)-CN-4)(4)] and AgSO(3)CF(3), [FeI(2)(CNC(6)H(2)-Me(2)-2,6-CN-4)(4)] and [Rh(2)(O(2)CCF(3))(4)], and [Mn(CNC(6)H(4)-CN-4)(6)][SO(3)CF(3)] and [Rh(2)(O(2)CCF(3))(4)]. [PdI(2)(CNC(6)H(4)-CN-4)(2)] and [Cu(hfacac)(2)] in a ratio of 1:2 form a crystalline, one-dimensional solid: monoclinic, space group P2(1)/c, a = 8.317(2) ?, b = 13.541(1) ?, c = 22.568(5) ?, beta = 100.45(1) degrees, Z = 2, 3279 unique reflections, R = 0.037, R(w) = 0.047.     

A convenient route to synthesize the fully conjugated bimetallic complex (Bu4N)2[tto[Ni(dmit)2]] (tto = tetrathiooxalate,C2S4(2-), and dmit = 1,3-dithiole-2-thione-4,5-dithiolate,C3S5(2-) and the crystal structure of a new crystal form

A novel route for the conversion of (Bu4N)2[Ni(dmit)2] to (Bu4N)2[tto[Ni(dmit)2]] is reported here. This provides a much more efficient way of synthesizing (Bu4N)2[tto[Ni(dmit)2]] than the literature method. During the process, the conversion of dmit2- to tto2- was realized for the first time. This new synthesis should facilitate further research on the conducting bimetallic complexes [C]x[tto[Ni(dmit)2]]. In addition, a new crystal form of (Bu4N)2[tto[Ni(dmit)2]]. In addition, a new crystal form of (Bu4N)2[tto[Ni(dmit)2]] was determined by X-ray crystallographic analysis.     

Self-assembly and redox modulation of the cavity size of an unusual rectangular iron thiolate aryldiisocyanide metallocyclophane

The decarbonylation reaction of ferric carbonyl dicationic [Cp(2)Fe(2)(μ-SEt)(2)(CO)(2)](BF(4))(2) [1(BF(4))(2)] carried out in refluxing acetonitrile affords a binuclear iron-sulfur core complex [Cp(2)Fe(2)(μ-SEt)(2)(CH(3)CN)(2)](BF(4))(2) [2(BF(4))(2)] containing two acetonitrile coordinated ligands. The treatment of 2(BF(4))(2) with 2 equiv of the 1,4-diisocyanobenzene (1,4-CNC(6)H(4)NC) results in the formation of the diisocyanide complex [Cp(2)Fe(2)(μ-SEt)(2)(1,4-CNC(6)H(4)NC)(2)](BF(4))(2) [3(BF(4))(2)]. The rectangular tetranuclear iron thiolate aryldiisocyanide metallocyclophane complex [Cp(4)Fe(4)(μ-SEt)(4)(μ-1,4-CNC(6)H(4)NC)(2)](BF(4))(4) [4(BF(4))(4)] has been synthesized by a self-assembly reaction between equimolar amounts of 2(BF(4))(2) and 1,4-diisocyanobenzene or by a stepwise route involving mixing of a 1:1 molar ratio of complexes 2(BF(4))(2) and 3(BF(4))(2). Chemical reduction of 4(BF(4))(4) by KC(8) was observed to produce the reduction product 4(BF(4))(2). The spectroscopic and electrochemical properties of the iron-sulfur core complexes 1(PF(6))(2), 3(BF(4))(2), 4(BF(4))(4), and 4(BF(4))(2) were determined. Finally, differences between the redox control cavities of rectangular tetranuclear iron thiolate aryldiisocyanide complexes are revealed by a comparison of the X-ray crystallographically determined structures of complexes 4(BF(4))(4) and 4(BF(4))(2).     

Synthesis, reactivity, and structure of strictly homologous 18 and 19 valence electron iron nitrosyl complexes

The 18 and 19 valence electron (VE) nitrosyl complexes [Fe(NO)('pyS4')]BF4 ([1]BF4) and [Fe(NO)('pyS4')] (2) have been synthesized from [Fe('pyS4')]x ('pyS4'(2-) = 2,6-bis(2-mercaptophenylthiomethyl)pyridine(2-)) and either NOBF4 or NO gas. Complex [1]BF4 was also obtained from [Fe(CO)('pyS4')] and NOBF4. The cation [1]+ is reversibly reduced to give 2. Oxidation of 2 by [Cp2Fe]PF6 afforded [Fe(NO)('pyS4')]PF6 ([1]PF6). The molecular structures of [1]PF6 and 2 were determined by X-ray crystallography. They demonstrate that addition of one electron to [1]+ causes a significant elongation of the Fe-donor atom bonds and a bending of the FeNO angle. Density functional calculations show that the unpaired electron in 2 occupies an orbital, which is antibonding with respect to all Fe-ligand interactions. As expected from qualitative Molecular Orbital (MO) theory, it has a large contribution from a pi* type NO orbital. The nu(NO) frequency decreases from 1893 cm(-1) in [1]BF4 to 1648 cm(-1) in 2 (in KBr). The antibonding character of the unpaired electron explains the ready reaction of 2 with excess NO to give [Fe(NO)2('pyS4')] (3), the facile NO/CO exchange of 2 to afford [Fe(CO)('pyS4')], and the easy oxidation of 2 to [1]+.     

Metal-induced coordination inversion and carbon-nitrogen bond rearrangement. Structurally characterized phenyl isocyanate inserted into aluminum methyl compounds and O- and N-bound aluminum compounds

[C(4)H(3)N(CH(2)NMe(2))-2]AlMe(2) (1) is prepared in 88% yield by the reaction of substituted pyrrole [C(4)H(4)N(CH(2)NMe(2))-2] with 1 equiv of AlMe(3) in methylene chloride. Reaction of compound 1 with 1 equiv of phenyl isocyanate in toluene generates a seven-membered cycloaluminum compound [C(4)H(3)N[CH(2)NPh(CONMe(2))]-2] AlMe(2) (2). The phenyl isocyanate was inserted into the aluminum and dimethylamino nitrogen bond and induced an unusual rearrangement which results in C-N bond breaking and formation. A control experiment shows that the reaction of substituted pyrrole [C(4)H(4)N(CH(2)NMe(2))-2] with 1 equiv of phenyl isocyanate in diethyl ether yields a pyrrolyl attached urea derivative [C(4)H(3)N(CH(2)NMe(2))-2-[C(=O)NHPh]-1] (3). The demethanation reaction of AlMe(3) with 1 equiv of 3 in methylene chloride at 0 degrees C afforded O-bounded and N-bounded aluminum dimethyl compounds [C(4)H(3)N(CH(2)NMe(2))-2-[C(=O)NPh]-1]AlMe(2) (4a) and [C(4)H(3)N(CH(2)NMe(2))-2-[CO(=NPh)]-1]AlMe(2) (4b) in a total 78% yield after recrystallization. Both 4a and 4b are observed in (1)H NMR spectra; however, the relative ratio of 4a and 4b depends on the solvent used. Two equivalents of AlMe(3) was reacted with 3 in methylene chloride to yield a dinuclear aluminum compound AlMe(3)[C(4)H(3)N(CH(2)NMe(2))-2-[C(=O)NPh]-1] AlMe(2) (5). Reaction of 5 with another equivalent of ligand 3 results in the re-formation of compounds 4a and 4b.     

Tetranuclear [Rh4(mu-PyS2)2(diolefin)4] complexes as building blocks for new inorganic architectures: synthesis of coordination polymers and heteropolynuclear complexes with electrophilic d8 and d10 metal fragments

The reaction of [Rh4(mu-PyS2)2(cod)4] (PyS2 = 2,6-pyridinedithiolate, cod = 1,5-cyclooctadiene) with CF3SO3Me gave the cationic complex [Rh(4)(mu-PyS(2)Me)(2)(cod)4][CF3SO3]2 (1) with two 6-(thiomethyl)pyridine-2-thiolate bridging ligands from the attack of Me+ at the terminal sulfur atoms of the starting material. Under identical conditions [Rh4(mu-PyS2)2(tfbb)4] (tfbb = tetrafluorobenzobarrelene) reacted with CF3SO3Me to give the mixed-ligand complex [Rh(4)(mu-PyS2)(mu-PyS2Me)(tfbb)4][CF3SO3] 2. The nucleophilicity of the bridging ligands in the complexes [Rh4(mu-PyS2)2(diolefin)4] was exploited to prepare heteropolynuclear species. Reactions with [Au(PPh3)(Me2CO)][ClO4] gave the hexanuclear complexes [(PPh3)2Au2Rh4(mu-PyS2)2(diolefin)4][ClO4]2 (diolefin = cod (3), tfbb (4)). The structure of 4, solved by X-ray diffraction methods, showed the coordination of the [Au(PPh3)]+ fragments to the peripheral sulfur atoms in [Rh4(mu-PyS2)2(diolefin)4] along with their interaction with the neighbor rhodium atoms. Neutral coordination polymers of formula [ClMRh4(mu-PyS2)2(diolefin)4]n (M = Cu (5, 6), Au (7)) result from the self-assembly of alternating [Rh4(mu-PyS2)2(diolefin)4] ([Rh4]) blocks and MCl linkers. The formation of the infinite polymetallic chains was found to be chiroselective for M = Cu; one particular chain contains exclusively homochiral [Rh4] complexes. Cationic heterometallic coordination polymers of formula [MRh4(mu-PyS2)2(diolefin)4]n[BF4]n (M = Ag (8, 9), Cu (10, 11)) and [Rh5(mu-PyS2)2(diolefin)5]n[BF4]n (12, 13) result from the reactions of [Rh4] with [Cu(CH2CN)4]BF4, AgBF4, and [Rh(diolefin)(Me2CO)2]BF4, respectively. The heterometallic coordination polymers exhibit a weak electric conductivity in the solid state in the range (1.2-2.8) x 10(-7) S cm(-1).