Luminescent one- and two-dimensional extended structures and a loosely associated dimer based on platinum(II)-thallium(I) backbones

Neutralization reactions between (NBu4)2[ trans-Pt(C 6F5)2(CN)2] 1 and (NBu4)2[cis-Pt(C6F5)2(CN)2] 2 with TlPF 6 have been carried out, and the resulting structures of [trans,trans,trans-Tl2{Pt(C6F5)2(CN)2}.(CH3COCH3) ] n [4.(CH3COCH3)2] n and {Tl[Tl{cis-Pt(C6F5)2(CN)2}].(H2O)} n [5.(H2O)] n have been determined by X-ray crystallography. Remarkably, the change from trans to cis geometry on the platinum substrate causes a significant decrease in the Pt(II)...Tl(I) metallophilic interaction. Thus, the platinum center in the trans fragment easily connects with two Tl(I) ions forming a distorted pseudo-octahedron PtTl2, which generates a final two-dimensional layered structure by secondary additional intermolecular Tl(I)...N(CN) interactions. However, the [cis-Pt(C6F5)2(CN)2] (2-) fragment interacts strongly with just one Tl center leading to an extended helical [-Pt-Tl-Pt-Tl-] n(n-) chain. In this case, the second thallium center neutralizes the anionic chain mainly through Tl...N(CN) ( intra) and Tl...F(C 6F 5) (intra and inter)actions. The reaction of TlPF 6 with the monoanionic fragment (NBu4)[cis-Pt(C6F5)2(CN)(PPh2C[triple bond]CPh)] 3 yields the discrete associated dimer [Tl{cis-Pt(C6F5)2(CN)(PPh2C[triple bond]CPh)}] 2 [ 6] 2. Dimer [ 6] 2 could be described as two square pyramids with the thallium atoms in the apical positions, connected through Tl...N(cyano) interactions. The final heteropolynuclear Pt-Tl complexes, except 4 at room temperature, show bright emission in the solid state when irradiated with UV-vis radiation, in contrast to the precursors 1 and 3, which are not luminescent. This difference indicates that the emissions in 4- 6 are presumably related to the interaction between the metal centers. The Pt-Tl bonding interactions and, consequently, the emissive properties are lost in solution at room temperature, as shown by the conductivity and NMR measurements. However, variable-concentration luminescence measurements in glassy acetonitrile solutions indicate the formation of different aggregates with different degrees of Pt...Tl interactions for 4 and 5 and a dimeric structure similar to that observed in solid state for 6.     

Novel luminescent mixed-metal Pt-Tl-alkynyl-based complexes: the role of the alkynyl substituent in metallophilic and eta2(pi...Tl)-bonding interactions

A novel series of [PtTl(2)(C[triple chemical bond]CR)(4)](n) (n = 2, R = 4-CH(3)C(6)H(4) (Tol) 1, 1-naphthyl (Np) 2; n = infinity, R = 4-CF(3)C(6)H(4) (Tol(F)) 3) complexes has been synthesized by neutralization reactions between the previously reported [Pt(C[triple chemical bond]CR)(4)](2-) (R = Tol, Tol(F)) or novel (NBu(4))(2)[Pt(C[triple chemical bond]CNp)(4)] platinum precursors and Tl(I) (TlNO(3) or TlPF(6)). The crystal structures of [Pt(2)Tl(4)(C[triple chemical bond]CTol)(8)]4 acetone, 14 acetone, [Pt(2)Tl(4)(C[triple chemical bond]CNp)(8)]3 acetone1/3 H(2)O, 23 acetone 1/3 H(2)O and [[PtTl(2)(C[triple chemical bond]CTol(F))(4)](acetone)S](infinity) (S = acetone 3 a; dioxane 3 b) have been solved by X-ray diffraction studies. Interestingly, whereas in the tolyl (1) and naphthyl (2) derivatives, the thallium centers exhibit a bonding preference for the electron-rich alkyne entities to yield crystal lattices based on sandwich hexanuclear [Pt(2)Tl(4)(C[triple chemical bond]CR)(8)] clusters (with additional Tlacetone (1) or Tlnaphthyl (2) secondary interactions), in the C(6)H(4)CF(3) (Tol(F)) derivatives 3 a and 3 b the basic Pt(II) center forms two unsupported Pt-Tl bonds. As a consequence 3 a and 3 b form an extended columnar structure based on trimetallic slipped PtTl(2)(C[triple chemical bond]CTol(F))(4) units that are connected through secondary Tl(eta(2)-acetylenic) interactions. The luminescent properties of these complexes, which in solution (blue; CH(2)Cl(2) 1,2; acetone 3) are very different to those in solid state (orange), have been studied. Curiously, solid-state emission from 1 is dependent on the presence of acetone (green) and its crystallinity. On the other hand, while a powder sample of 3 is pale yellow and displays blue (457 nm) and orange (611 nm) emissions, the corresponding pellets (KBr, solid) of 3, or the fine powder obtained by grinding, are orange and only exhibit a very intense orange emission (590 nm).     

Copolymerisation of Pt-carbonyl clusters with Lewis acids: synthesis and crystal structure of the molecular [Cd2Cl4[Pt9(CO)18]2-]infinity 1-D polymer

Reaction of [NBu4]2[Pt9(CO)18] with the soft Lewis acid CdCl2 gives the [Pt9(CO)18(micro3-CdCl2)2]2- adduct, which self-assembles upon crystallization into a 1-D [[Pt9(CO)18(micro3-CdCl2)2]2-]infinity polymer via the formation of chloride bridges.     

Pt]2Pb trinuclear systems: impact of the anionic platinum fragment on the lead environment and photoluminescence

A comparison of the solid structures of three novel trinuclear sandwich Pt 2Pb systems (NBu 4) 2[{Pt(C identical withCTol) 4} 2Pb(OH 2) 2] 1, [{Pt(bzq)(C identical withCPh) 2} 2Pb] 2, and (NBu 4)[{Pt(bzq)(C identical withCC 6H 4-CF 3-4) 2} 2Pb(O 2ClO 2)] 4 (NBu 4[ 3.(O 2ClO 2)]) with that of the previously reported (NBu 4) 2[{Pt(C 6F 5) 4} 2Pb] 5 showed that the local environment of Pb (II) is highly sensitive to the nature of the anionic platinate(II) precursors. The photoluminescence (PL) studies of all 1- 5 complexes revealed a dependence of PL on the structure type. Thus, complexes 1 and 5 exhibit metal centered emissions ( 1, 497 nm, 77 K; 5, 539 nm, varphi = 0.43, 298 K) related to the linear ( 5) or bent ( 1 Pt-Pb-Pt 149.9 degrees ) trinuclear entities. However, in complexes 2- 4, that have unprecedented Pb (II)...eta (1)(C identical withCR) bonding interactions and very short Pt...Pb and Pt...Pt distances, the emissive state in solid state (77 K) is attributed to a (3)MLM'CT [Pt(1)pi(C identical withCR)-->Pt(2)/Pb(sp)pi*(C identical withCR)] state mixed with some pipi* excimeric character in neutral complexes 2 (R = Ph) and 3 (R = C 6H 4-CF 3-4), and in the case of the adduct (NBu 4)[{Pt(bzq)(C identical withCC 6H 4-CF 3-4) 2} 2Pb(O 2ClO 2)] 4 modified also by Pb (II)...O (O 2ClO 2 (-)) contacts.     

Unsupported gold(I)-copper(I) interactions through eta1 Au-[Au(C6F5)2]- coordination to Cu+ Lewis acid sites

The reaction of the complex [Au2Ag2(C6F5)4)N[triple bond]CCH3)2]n (1) with 1 equiv of CuCl in the presence of 1 equiv of pyrimidine ligand leads to the formation of the heteronuclear Au(I)-Cu(I) organometallic polymer [Cu{Au(C6F5)2}(N[triple bond]CCH3)(mu2-C4H4N2)]n (2) through a transmetalation reaction. Complex 2 displays unprecedented unsupported Au(I)...Cu(I) interactions of [Au(C6F5)2]- units with the acid Cu(I) sites in a [Cu(N[triple bond]CCH3)(mu2-pyrimidine)]n+(n) polymeric chain. Complex 2 has a rich photophysics in solution and in the solid state.     

Syntheses; 77Se, 203Tl, and 205Tl NMR; and theoretical studies of the Tl2Se6(6-), Tl3Se6(5-), and Tl3Se7(5-) anions and the X-ray crystal structures of [2,2,2-crypt-Na]4[Tl4Se8].en and [2,2,2-crypt-Na]2[Tl2Se4](infinity)1.en

The 2,2,2-crypt salts of the Tl4Se8(4-) and [Tl2Se4(2-)]infinity1 anions have been obtained by extraction of the ternary alloy NaTl0.5Se in ethylenediamine (en) in the presence of 2,2,2-crypt and 18-crown-6 followed by vapor-phase diffusion of THF into the en extract. The [2,2,2-crypt-Na]4[Tl4Se8].en crystallizes in the monoclinic space group P2(1)/n, with Z = 2 and a = 14.768(3) angstroms, b = 16.635(3) angstroms, c = 21.254(4) angstroms, beta = 94.17(3) degrees at -123 degrees C, and the [2,2,2-crypt-Na]2[Tl2Se4]infinity1.en crystallizes in the monoclinic space group P2(1)/c, with Z = 4 and a = 14.246(2) angstroms, b = 14.360(3) angstroms, c = 26.673(8) angstroms, beta = 99.87(3) degrees at -123 degrees C. The TlIII anions, Tl2Se6(6-) and Tl3Se7(5-), and the mixed oxidation state TlI/TlIII anion, Tl3Se6(5-), have been obtained by extraction of NaTl0.5Se and NaTlSe in en, in the presence of 2,2,2-crypt and/or in liquid NH3, and have been characterized in solution by low-temperature 77Se, 203Tl, and 205Tl NMR spectroscopy. The 1J(203,205Tl-77Se) and 2J(203,205Tl-203,205Tl) couplings of the three anions have been used to arrive at their solution structures by detailed analyses and simulations of all spin multiplets that comprise the 205,203Tl NMR subspectra arising from natural abundance 205,203Tl and 77Se isotopomer distributions. The structure of Tl2Se6(6-) is based on a Tl2Se2 ring in which each thallium is bonded to two exo-selenium atoms so that these thalliums are four-coordinate and possess a formal oxidation state of +3. The Tl4Se8(4-) anion is formally derived from the Tl2Se6(6-) anion by coordination of each pair of terminal Se atoms to the TlIII atom of a TlSe+ cation. The structure of the [Tl2Se4(2-)]infinity1 anion is comprised of edge-sharing distorted TlSe4 tetrahedra that form infinite, one-dimensional [Tl2Se42-]infinity1 chains. The structures of Tl3Se6(5-) and Tl3Se7(5-) are derived from Tl4Se4-cubes in which one thallium atom has been removed and two and three exo-selenium atoms are bonded to thallium atoms, respectively, so that each is four-coordinate and possesses a formal oxidation state of +3 with the remaining three-coordinate thallium atom in the +1 oxidation state. Quantum mechanical calculations at the MP2 level of theory show that the Tl2Se6(6-), Tl3Se6(5-), Tl3Se7(5-), and Tl4Se8(4-) anions exhibit true minima and display geometries that are in agreement with their experimental structures. Natural bond orbital and electron localization function analyses were utilized in describing the bonding in the present and previously published Tl/Se anions, and showed that the Tl2Se6(6-), Tl3Se6(5-), Tl3Se7(5-), and Tl4Se8(4-) anions are electron-precise rings and cages.     

Palladium(II) and platinum(II) organometallic complexes with 4,7-dihydro-5-methyl-7-oxo[1,2,4]triazolo[1,5-a]pyrimidine. Antitumor activity of the platinum compounds

Palladium and platinum complexes with HmtpO (where HmtpO=4,7-dihydro-5-methyl-7-oxo[1,2,4]triazolo[1,5-a]pyrimidine, an analogue of the natural occurring nucleobase hypoxanthine) of the types [M(dmba)(PPh3)(HmtpO)]ClO4[dmba=N,C-chelating 2-(dimethylaminomethyl)phenyl; M=Pd or Pt], [Pd(N-N)(C6F5)(HmtpO)]ClO4[N-N=2,2'-bipyridine (bpy), 4,4'-dimethyl-2,2'-bipyridine (Me2bpy), or N, N, N', N'-tetramethylethylenediamine (tmeda)] and cis-[M(C6F5)2(HmtpO)2] (M=Pd or Pt) (head-to-head atropisomer in the solid state) have been obtained. Pd(II) and Pt(II) complexes with the anion of HmtpO of the types [Pd(tmeda)(C6F5)(mtpO)], [Pd(dmba)(micro-mtpO)] 2, and [NBu4]2[M(C6F5)2(micro-mtpO)]2(M=Pd or Pt) have been prepared starting from the corresponding hydroxometal complexes. Complexes containing simultaneously both the neutral HmtpO ligand and the anionic mtpO of the type [NBu4][M(C6F5)2(HmtpO)(mtpO)] (M=Pd or Pt) have been also obtained. In these mtpO-HmtpO metal complexes, for the first time, prototropic exchange is observed between the two heterocyclic ligands. The crystal structures of [Pd(dmba)(PPh 3)(HmtpO)]+, cis-[Pt(C6F5)2(HmtpO)2].acetone, [Pd(C6F5)(tmeda)(mtpO)].2H2O, [Pd(dmba)(micro-mtpO)]2, [NBu4]2[Pd(C6F5)2(micro-mtpO)]2.CH2Cl2.toluene, [NBu4]2[Pt(C6F5)2(micro-mtpO)](2).0.5(toluene), and [NBu4][Pt(C6F5)2(mtpO)(HmtpO)] have been established by X-ray diffraction. Values of IC50 were calculated for the new platinum complexes cis-[Pt(C6F5)2(HmtpO)2] and [Pt(dmba)(PPh3)(HmtpO)]ClO4 against a panel of human tumor cell lines representative of ovarian (A2780 and A2780 cisR), lung (NCI-H460), and breast cancers (T47D). At 48 h incubation time, both complexes were about 8-fold more active than cisplatin in T47D and show very low resistance factors against an A2780 cell line, which has acquired resistance to cisplatin. The DNA adduct formation of cis-[Pt(C6F5)2(HmtpO)2] and [Pt(dmba)(PPh3)(HmtpO)]ClO4 was followed by circular dichroism and electrophoretic mobility. Atomic force microscopy images of the modifications caused by these platinum complexes on plasmid DNA pB R322 were also obtained.     

Triazenide-bridged rhodium-palladium complexes: [I2Rh(mu-p-MeC6H4NNNC6H4Me-p)2Pd(eta(3)-C3H5)]-, a stable paramagnetic [RhPd]4+ species with a localised Rh(II) centre

Deprotonation of mixtures of the triazene complexes [RhCl(CO)2(p-MeC6H4NNNHC6H4Me-p)] and [PdCl(eta(3)-C3H5)(p-MeC6H4NNNHC6H4Me-p)] or [PdCl2(PPh3)(p-MeC6H4NNNHC6H4Me-p)] with NEt3 gives the structurally characterised heterobinuclear triazenide-bridged species [(OC)2Rh(mu-p-MeC6H4NNNC6H4Me-p)2PdLL'] {LL' = eta(3)-C3H5 1 or Cl(PPh3) 2} which, in the presence of Me3NO, react with [NBu(n)4]I, [NBu(n)4]Br, [PPN]Cl or [NBu(n)4]NCS to give [(OC)XRh(mu-p-MeC6H4NNNC6H4Me-p)2PdCl(PPh3)]- (X = I 3-, Br 4-, Cl 5- or NCS 6-) and [NBu(n)4][(OC)XRh(mu-p-MeC6H4NNNC6H4Me-p)2Pd(eta(3)-C3H5)], (X = I 7- or Br 8-). The allyl complexes 7- and 8- undergo one-electron oxidation to the corresponding unstable neutral complexes 7 and 8 but, in the presence of the appropriate halide, oxidative substitution results in the stable paramagnetic complexes [NBu(n)4][X2Rh(mu-p-MeC6H4NNNC6H4Me-p)2Pd(eta(3)-C3H5)], (X = I 9- or Br 10-). X-Ray structural (9-), DFT and EPR spectroscopic studies are consistent with the unpaired electron of 9- and 10- localised primarily on the Rh(II) centre of the [RhPd]4+ core, which is susceptible to oxygen coordination at low temperature to give Rh(III)-bound superoxide.     

203,205Tl NMR studies of crystallographically characterized thallium alkoxides. X-ray Structures of [TI(OCH2CMe3)]4 and [TI(OAr)]infinity, where OAr = OC6H3(Me)2-2,6 and OC6H3(CHMe2)2-2,6

[Tl(OCH2Me)]4 (1) was reacted with excess HOR to prepare a series of [Tl(OR)]n, where OR = OCHMe2 (2, n = 4), OCMe3 (3, n = 4), OCH2CMe3 (4, n = 4), OC6H3(Me)2-2,6 (5, n = infinity), and OC6H3(CHMe2)2-2,6 (6, n = infinity). Single-crystal X-ray diffraction experiments revealed that in the solid state the alkoxide-ligated compound 4 adopts a cubane structure, whereas the aryloxide derivatives, 5 and 6, formed polymeric chains. Compounds 1-6 were also characterized by 203,205Tl solution and 205Tl solid-state NMR spectroscopy. In solution it was determined that 1-4 retained the [Tl-O]4 cube structure, whereas the polymeric species 5 and 6 appeared to be fluxional. Variations in the solution and solid-state structures for the [Tl(OR)]4 cubes and polymeric [Tl(OAr)]infinity are influenced by the steric hindrance of the ligand. The acidity of the parent alcohol influences the degree of covalency at the Tl metal center, which is reflected in the 203,205Tl chemical shifts for 1-6.     

Binuclear Pt-Tl bonded complex with square pyramidal coordination around Pt: a combined multinuclear NMR, EXAFS, UV-Vis, and DFT/TDDFT study in dimethylsulfoxide solution

The structure and bonding of a new Pt-Tl bonded complex formed in dimethylsulfoxide (dmso), (CN)(4)Pt-Tl(dmso)(5)(+), have been studied by multinuclear NMR and UV-vis spectroscopies, and EXAFS measurements in combination with density functional theory (DFT) and time dependent density functional theory (TDDFT) calculations. This complex is formed following the equilibrium reaction Pt(CN)(4)(2-) + Tl(dmso)(6)(3+) ? (CN)(4)Pt-Tl(dmso)(5)(+) + dmso. The stability constant of the Pt-Tl bonded species, as determined using (13)C NMR spectroscopy, amounts to log K = 2.9 ± 0.2. The (NC)(4)Pt-Tl(dmso)(5)(+) species constitutes the first example of a Pt-Tl bonded cyanide complex in which the sixth coordination position around Pt (in trans with respect to the Tl atom) is not occupied. The spectral parameters confirm the formation of the metal-metal bond, but differ substantially from those measured earlier in aqueous solution for complexes (CN)(5)Pt-Tl(CN)(n)(H(2)O)(x)(n-) (n = 0-3). The (205) Tl NMR chemical shift, δ = 75 ppm, is at extraordinary high field, while spin-spin coupling constant, (1)J(Pt-Tl) = 93 kHz, is the largest measured to date for a Pt-Tl bond in the absence of supporting bridging ligands. The absorption spectrum is dominated by two strong absorption bands in the UV region that are assigned to MMCT (Pt → Tl) and LMCT (dmso → Tl) bands, respectively, on the basis of MO and TDDFT calculations. The solution of the complex has a bright yellow color as a result of a shoulder present on the low energy side of the band at 355 nm. The geometry of the (CN)(4)Pt-Tl core can be elucidated from NMR data, but the particular stoichiometry and structure involving the dmso ligands are established by using Tl and Pt L(III)-edge EXAFS measurements. The Pt-Tl bond distance is 2.67(1) ?, the Tl-O bond distance is 2.282(6) ?, and the Pt-C-N entity is linear with Pt-C and Pt···N distances amounting to 1.969(6) and 3.096(6) ?, respectively. Geometry optimizations on the (CN)(4)Pt-Tl(dmso)(5)(+) system by using DFT calculations (B3LYP model) provide bond distances in excellent agreement with the EXAFS data. The four cyanide ligands are located in a square around the Pt atom, while the Tl atom is coordinated in a distorted octahedral fashion with the metal being located 0.40 ? above the equatorial plane described by four oxygen atoms of dmso ligands. The four equatorial Tl-O bonds and the four cyano ligands around the Pt atom are arranged in an alternate geometry. The coordination environment around Pt may be considered as being square pyramidal, where the apical position is occupied by the Tl atom. The optimized geometry of (CN)(4)Pt-Tl(dmso)(5)(+) is asymmetrical (C(1) point group). This low symmetry might be responsible for the unusually large NMR linewidths observed due to intramolecular chemical exchange processes. The nature of the Pt-Tl bond has been studied by MO analysis. The metal-metal bond formation in (CN)(4)Pt-Tl(dmso)(5)(+) can be simply interpreted as the result of a Pt(5d(z(2)))(2) → Tl(6s)(0) donation. This bonding scheme may rationalize the smaller thermodynamic stability of this adduct compared to the related complexes with (CN)(5)Pt-Tl entity, where the linear C-Pt-Tl unit constitutes a very stable bonding system.     

Nitrile-amidine coupling at Pt(IV) and Pt(II) centers. An easy entry to imidoylamidine complexes

Treatment of trans-[PtCl4(RCN)2] (R = Me, Et, Ph, NEt2) with 2 equiv of the amidine PhC(=NH)NHPh in a suspension of MeCN (R = Me), CHCl3 (R = Et, Ph), or in CHCl3 solution (R = NEt2) results in the formation of the imidoylamidine complexes trans-[PtCl4{NH=C(R)N=C(Ph)NHPh}2] (1-4) isolated in good yields (66-84%). The reaction of soluble complexes 3 and 4 with 2 equiv of Ph3P=CHCO2Me in CH2Cl2 (40 degrees C, 5 h) leads to dehydrochlorination resulting in a chelate ring closure to furnish the platinum(IV) chelates [PtCl2{NH=C(R)NC(Ph)=NPh}2] (R = Ph, 5; R = NEt2, 6), accordingly, and the phosphonium salt [Ph3PCH2CO2Me]Cl. Treatment of 5 with 3 equiv of Ph3P=CHCO2Me at 50 degrees C for 5 d resulted in only a 30% conversion to the corresponding Pt(II) complex [Pt{NH=C(NEt2)NC(Ph)=NPh}2] (15). The reduction can be achieved within several minutes, when Ph2PCH2CH2PPh2 in CDCl3 is used. When the platinum(II) complex trans-[PtCl2(RCN)2] is reacted with 2 equiv of the amidine, the imidoylamidinato complexes [PtCl(RCN){NH=C(R)NC(Ph)=NHPh}] (8-11) and [PhC(=NH)NHPh] x HCl (7) are formed. The reaction of trans-[PtCl2(RCN)2] with 4 equiv of the amidine under a prolonged reaction time or treatment of [PtCl(RCN){NH=C(R)NC(Ph)=NHPh}] (8-11) with 2 more equiv of the amidine yields the complex bearing two chelate rings [Pt{NH=C(R)NC(Ph)=NHPh}2] (12-15). The treatment of cis-[PtCl2(RCN)2] (R = Me, Et) with the amidine gives ca. 50-60% yield of [PtCl2{NH=C(R)NHC(Ph)=NHPh}] (16 and 17). All of the platinum compounds were characterized by elemental analyses; FAB mass spectrometry; IR spectroscopy; 1H, 13C{1H}, and 195Pt NMR spectroscopies, and four of them (4, 6, 8, and 15) were also characterized by X-ray crystallography. The coupling of the Pt-bound nitriles and the amidine is metal-mediated insofar as RCN and PhC(=NH)NHPh do not react in the absence of the metal centers in conditions more drastic than those of the observed reactions. The nitrile-amidine coupling reported in this work constitutes a route to the synthesis of imidoylamidine complexes, some of them exhibiting luminescent properties.     

Copper(I) coordination polymers [{Cu(mu-X)}2{RP(mu-NtBu)}2]n (R = OC6H4OMe-o; X = Cl, Br, and I) and their reversible conversion into mononuclear complexes [CuX{(RP(mu-NtBu)2}2]: synthesis and structural characterization

The reactions of cyclodiphosphazane cis-[tBuNP(OC6H4OMe-o)]2 (1) with 2 equiv of CuX in acetonitrile afforded one-dimensional Cu(I) coordination polymers [Cu2X2{tBuNP(OC6H4OMe-o)}2]n (2, X = Cl; 3, X = Br; 4, X = I). The crystal structures of 2 and 4 reveal a zigzag arrangement of [P(mu-N)(2)P] and [Cu(mu-X)(2)Cu] units in an alternating manner to form one-dimensional Cu(I) coordination polymers. The reaction between 1 and CuX in a 2:1 ratio afforded mononuclear tricoordinated copper(I) complexes of the type [CuX{(tBuNP(OC6H4OMe-o))2}2] (5, X = Cl; 6, X = Br; 7, X = I). The single-crystal structures were established for the mononuclear copper(I) complexes 5 and 6. When the reactant ratios are 1:1, the formation of a mixture of polymeric and mononuclear products was observed. The Cu(I) polymers (2-4) were converted into the mononuclear complexes (5-7) by reacting with 3 equiv of 1 in dimethyl sulfoxide. Similarly, the mononuclear complexes (5-7) were converted into the corresponding polymeric complexes (2-4) by reacting with 3 equiv of copper(I) halide under mild reaction conditions.     

Thallium(I) sandwich, multidecker, and ether complexes stabilized by weakly-coordinating anions: a spectroscopic, structural, and theoretical investigation

The reaction of thallium ethoxide with [H(OEt2)2][H2N{B(C6F5)3}2] in diethyl ether afforded [Tl(OEt2)3][H2N{B(C6F5)3}2] (2a), [Tl(OEt2)4][H2N{B(C6F5)3}2] (2b), or [Tl(OEt2)2][H2N{B(C6F5)3}2].CH2Cl2 (2c), depending on the reaction conditions. The dication in the hydrolysis product [Tl4(mu3-OH)2][H2N{B(C6F5)3}2]2.4CH2Cl2 consists of two bridging and two terminal Tl+ ions bound to triply bridging hydroxides. Heating Et2O complexes in toluene afforded [Tl(eta6-toluene)n][H2N{B(C6F5)3}2] (4, n = 2, 3), while C6Me6 addition gave the first thallium-C6Me6 adduct, [Tl(eta6-C6Me6)2][H2N{B(C6F5)3}2].1.5CH2Cl2 (5a), a bent sandwich complex with very short Tl...centroid distances. These arene complexes show no close contacts between cations and anions. Displacement of toluene ligands by ferrocene gave [Tl2(FeCp2)3][H2N{B(C6F5)3}2]2.5CH2Cl2 (6) which contains the multidecker cations [Tl(FeCp2)]+ and [Tl(FeCp2)2]+ in a 1:1 ratio. By contrast, decamethylferrocene leads to electron transfer; the isolable thallium-ferrocene complexes may therefore be viewed as precursor complexes for this redox step. With 18-crown-6 the complexes [Tl(18-crown-6)2][H2N{B(C6F5)3}2] (11a) and [Tl(18-crown-6)][H2N{B(C6F5)3}2].2CH2Cl2 (11b) were isolated. The structure of the latter shows an eight-coordinate thallium ion, where the coordination to the six oxygen donors in equatorial positions is completed by axial contacts to two F atoms of the counter anions. The bonding between thallium(I) and arenes was explored by density-functional theory (DFT) calculations. The optimized geometry of [Tl(tol)3]+ converged to a structure very similar to that obtained experimentally. Calculations on [Tl(C6Me6)2]+ (5b) to establish whether a linear or bent geometry is the most stable revealed a very flat potential-energy surface for distortions of the Ctr(3)-Tl-Ctr(4) angle. Overall, there is very little energetic preference for one particular geometry over another above about 140 degrees , in good agreement with the crystallographic geometry. The calculated Tl-arene interaction energies increase from 73.7 kJ mol-1 for toluene to 121.7 kJ mol-1 for C6Me6.     

Influence of solvent and weak C-H...O contacts in the self-assembled [Pt2M4{CC(3-OMe)C6H4}8] (M = Cu, Ag) clusters and their role in the luminescence behavior

New alkynyl complexes [Pt2M4{CC(3-OMe)C6H4}8] (M = Ag 1, Cu 2) have been synthesized and their structures and properties compared to those of related [Pt2M4(CCPh)8] compounds. For the Pt-Ag derivatives, the X-ray structures of the discrete yellow solvate monomer, [Pt2Ag4{CC(3-OMe)C6H4}8].2THF ([1.2THF]), and the dark garnet unsolvated polymeric form, [Pt2Ag4{CC(3-OMe)C6H4}8](infinity) ([1](infinity)), are presented. The yellow form ([1.2THF]) exhibits a distorted octahedral geometry of the metal centers with the platinum atoms mutually trans and the four silver atoms in the equatorial plane. Pairs of Ag atoms are weakly bridged by THF molecules [mu-Ag2...O(THF)]. The garnet form ([1](infinity)) has an unprecedented infinite stacked chain of octahedral clusters linked by short Pt...Pt bonds (3.1458(8) A). In both forms, different types of weak C-H...O (OMe) hydrogen bonds are observed. For comparative purposes, we have also provided the crystal structures of the yellow monomer form, [Pt2Ag4-(CCPh)8].CHCl3, and the red dimer form, [Pt2Ag4(CCPh)8]2 (Pt-Pt 3.221(2) A). These clusters display intense photoluminescence in both solution and the solid state, at room temperature and 77 K. The emission observed for the yellow form [1.2THF] in the solid state is assigned to a 3MLM'CT [Pt(d)/pi(CCR) --> Pt(p(z))/Ag(sp)/pi(CCR)] state modified by Pt...Ag, Ag...Ag, and Ag...(THF) contacts. However, in the garnet form [1](infinity) and in 2, the emissions are related to the axial Pt-Pt bonds and are assigned as phosphorescence from a metal-metal-to-ligand charge-transfer (3MMLCT) excited state ([1](infinity)), or an admixture of a metal-metal (Pt-Pt) centered 3(dsigmap(z)sigma) and 3MMLCT excited state (2). For 1, a remarkable quenching and a shift to higher energies in the emission is observed on changing from CH2Cl2 to THF, and for both 1 and 2, the emission spectra at 77 K varies with the concentration, showing their tendency to stack even in glass.     

Highly reduced, polyoxo(alkoxo)vanadium(III/IV) clusters

A family of high nuclearity oxo(alkoxo)vanadium clusters in unprecedentedly low oxidation states is reported, synthesised from simple vanadium diketonate precursors in alcohols under solvothermal conditions. Crystal structures of [V18(O)12(OH)2(H2O)4(EtO)22(O2CPh)6(acac)2] (1), [V16Na2(O)18(EtO)16(EtOH)2(O2CPh)6(HO2CPh)2]infinity (2), [V13(O)13(EtO)15(EtOH)(RCO2)3] in which R=adamantyl (3) or Ph3C (4), and [V11(O)12(EtO)13(EtOH)(Ph3CCO2)2(MePO3)] (5) are reported, revealing these to be {VIII 16VIV 2} (1), {VIII 9VIV 3VV} (3 and 4) and {VIII 3VIV 8} (5) clusters, while 2 consists of isolated {VIII 8VIV 8} clusters bridged into polymeric chains by {Na2(OEt)2} fragments. Solvothermal conditions are essential to the formation of these species, and the level of oxidation of the isolated clusters is in part controlled by the crystallisation time, with the lowest mean-oxidation-state species being isolated by direct crystallisation on controlled cooling of the reaction solutions.     

Mn12O12(OMe)2(O2CPh)16(H2O)2]2- single-molecule magnets and other manganese compounds from a reductive aggregation procedure

A new synthetic procedure has been developed in Mn cluster chemistry involving reductive aggregation of permanganate (MnO4-) ions in MeOH in the presence of benzoic acid, and the first products from its use are described. The reductive aggregation of NBu(n)4MnO4 in MeOH/benzoic acid gave the new 4Mn(IV), 8Mn(III) anion [Mn12O12(OMe)2(O2CPh)16(H2O)2]2-, which was isolated as a mixture of two crystal forms (NBu(n)4)2[Mn12O12(OMe)2(O2CPh)16(H2O)2].2H2O.4CH2Cl2 (1a) and (NBu(n)4)2[Mn12O12(OMe)2(O2CPh)16(H2O)2].2H2O.CH2Cl2 (1b). The anion of 1 contains a central [Mn(IV)4(mu3-O)2(mu-O)2(mu-OMe)2]6+ unit surrounded by a nonplanar ring of eight Mn(III) atoms that are connected to the central Mn4 unit by eight bridging mu3-O2- ions. This compound is very similar to the well-known [Mn12O12(O2CR)16(H2O)4] complexes (hereafter called "normal Mn12"), with the main difference being the structure of the central cores. Longer reaction times (approximately 2 weeks) led to isolation of polymeric [Mn(OMe)(O2CPh)2]n2, which contains a linear chain of repeating [Mn(III)(mu-O2CPh)2(mu-OMe)Mn(III)] units. The chains are parallel to each other and interact weakly through pi-stacking between the benzoate rings. When KMnO4 was used instead of NBu(n)4MnO4, two types of compounds were obtained, [Mn12O12(O2CPh)16(H2O)4] (3), a normal Mn12 complex, and [Mn4O2(O2CPh)8(MeOH)4].2MeOH (4.2MeOH), a new member of the Mn4 butterfly family. The cyclic voltammogram of 1 exhibits three irreversible processes, two reductions and one oxidation. One-electron reduction of 1 by treatment with 1 equiv of I- in CH2Cl2 gave (NBu(n)4[Mn12O12(O2CPh)16(H2O)3].6CH2Cl2 (5.6CH2Cl2), a normal Mn12 complex in a one-electron reduced state. The variable-temperature magnetic properties of 1, 2, and 5 were studied by both direct current (dc) and alternating current (ac) magnetic susceptibility measurements. Variable-temperature dc magnetic susceptibility studies revealed that (i) complex 1 possesses an S = 6 ground state, (ii) complex 2 contains antiferromagnetically coupled chains, and (iii) complex 5 is a typical [Mn12]- cluster with an S = 19/2 ground state. Variable-temperature ac susceptibility measurements suggested that 5 and both isomeric forms of 1 (1a,b) are single-molecule magnets (SMMs). This was confirmed by the observation of hysteresis loops in magnetization vs dc field scans. In addition, 1a,b, like normal Mn12 clusters, display both faster and slower relaxing magnetization dynamics that are assigned to the presence of Jahn-Teller isomerism.     

One-dimensional phosphinite platinum chains based on hydrogen bonding interactions and phosphinite tetranuclear platinum(II)-thallium(I) complexes

The mononuclear pentafluorophenyl platinum complex containing the chelated diphenylphosphinous acid/diphenylphosphinite system [Pt(C(6)F(5)){(PPh(2)O)(2)H}(PPh(2)OH)] 1 has been prepared and characterised. 1 and the related alkynyl complex [Pt(C[triple bond, length as m-dash]CBu(t)){(PPh(2)O)(2)H}(PPh(2)OH)] 2 form infinite one-dimensional chains in the solid state based on intermolecular O-H[dot dot dot]O hydrogen bonding interactions. Deprotonation reactions of [PtL{(PPh(2)O)(2)H}(PPh(2)OH)] (L = C(6)F(5), C[triple bond, length as m-dash]CBu(t), C[triple bond, length as m-dash]CPh 3) with [Tl(acac)] yields tetranuclear Pt(2)Tl(2) complexes [PtL{(PPh(2)O)(2)H}(PPh(2)O)Tl](2) (L = C(6)F(5) 4, C[triple bond, length as m-dash]CBu(t), C[triple bond, length as m-dash]CPh ). The structure of the tert-butylalkynyl derivative , established by X-ray diffraction, shows two anionic discrete units [Pt(C[triple bond, length as m-dash]CBu(t)){(PPh(2)O)(2)H}(PPh(2)O)](-) joined by two Tl(i) centres via Tl-O and Pt-Tl bonds. Despite the existence of Pt-Tl interactions, they do not show luminescence.     

Redistribution and fluxionality in heteropolyoxoperoxo complexes: [PO4[M2O2(mu-O2)2(O2)2]2]3- with M = Mo and/or W

When peroxotetramolybdophosphate, [(n-C4H9)4N]3[PO4[Mo2O2(mu-O2)2(O2)2]2], denoted (NBu4)3PMo4, and its tungsten(VI) analogue, (NBu4)3PW4, are mixed in acetonitrile at room temperature, redistribution occurs with the formation of three mixed-addenda species [PO4[Mo4-xWxO20]]3- (x = 1-3). The temperature dependence of the phosphorus-31 NMR spectra of a 1 1 mixture and of the pure salts, (NBu4)3PMo4 or (NBu4)3PW4, shows that [MO(O2)2] species are in chemical exchange, as are the [MOp] units of certain heteropolyacids (e.g. H3[PMo12O40] x aq and H3[PW12O40] x aq). However, there is no chemical exchange between free phosphate and [MO(O2)2] species in these systems; but there is fluxional behaviour involving PMo2W2, PMo4 and PW4. This is attributed to the rapid equilibrium between isomers (PMo2W2) and to equilibrium between anionic structures with tridentate (mu-eta2:eta1-O22-) and bidentate (eta2-O22-) modes of coordination for the two peroxo groups of the [M2O2(mu-O2)2(O2)2] moieties.     

Synthesis and characterization of the silver maleonitrilediselenolates and silver maleonitriledithiolates [K([2.2.2]-cryptand)]4[Ag4(Se2C2(CN)2)4], [Na([2.2.2]-cryptand)]4[Ag4(S2C2(CN)2)4].0.33MeCN, [NBu4]4[Ag4(S2C2(CN)2)4], [K([2.2.2]-cryptand)]3[Ag(Se2C2(CN)2)2].2MeCN, and [Na([2.2.2]-cryptand)]3[Ag(S2C2(CN)2)2

Reaction of AgBF(4), KNH(2), K(2)Se, Se, and [2.2.2]-cryptand in acetonitrile yields [K([2.2.2]-cryptand)](4)[Ag(4)(Se(2)C(2)(CN)(2))(4)] (1). In the unit cell of 1 there are four [K([2.2.2]-cryptand)](+) units and a tetrahedral Ag(4) anionic core coordinated in mu(1)-Se, mu(2)-Se fashion by each of four mns ligands (mns = maleonitrilediselenolate, [Se(2)C(2)(CN)(2)](2)(-)). Reaction of AgNO(3), Na(2)(mnt) (mnt = maleonitriledithiolate, [S(2)C(2)(CN)(2)](2)(-)), and [2.2.2]-cryptand in acetonitrile yields [Na([2.2.2]-cryptand)](4)[Ag(4)(mnt)(4)].0.33MeCN (2). The Ag(4) anion of 2 is analogous to that in 1. Reaction of AgNO(3), Na(2)(mnt), and [NBu(4)]Br in acetonitrile yields [NBu(4)](4)[Ag(4)(mnt)(4)] (3). The anion of 3 also comprises an Ag(4) core coordinated by four mnt ligands, but the Ag(4) core is diamond-shaped rather than tetrahedral. Reaction of [K([2.2.2]-cryptand)](3)[Ag(mns)(Se(6))] with KNH(2) and [2.2.2]-cryptand in acetonitrile yields [K([2.2.2]-cryptand)](3)[Ag(mns)(2)].2MeCN (4). The anion of 4 comprises an Ag center coordinated by two mns ligands in a tetrahedral arrangement. Reaction of AgNO(3), 2 equiv of Na(2)(mnt), and [2.2.2]-cryptand in acetonitrile yields [Na([2.2.2]-cryptand)](3)[Ag(mnt)(2)] (5). The anion of 5 is analogous to that of 4. Electronic absorption and infrared spectra of each complex show behavior characteristic of metal-maleonitriledichalcogenates. Crystal data (153 K): 1, P2/n, Z = 2, a = 18.362(2) A, b = 16.500(1) A, c = 19.673(2) A, beta = 94.67(1) degrees, V = 5941(1) A(3); 2, P4, Z = 4, a= 27.039(4) A, c = 15.358(3) A, V = 11229(3) A(3); 3, P2(1)/c, Z = 6, a = 15.689(3) A, b = 51.924(11) A, c = 17.393(4) A, beta = 93.51(1) degrees, V = 14142(5) A(3); 4, P2(1)/c, Z = 4, a = 13.997(1) A, b = 21.866(2) A, c = 28.281(2) A, beta = 97.72(1) degrees, V = 8578(1) A(3); 5, P2/n, Z = 2, a = 11.547(2) A, b = 11.766(2) A, c = 27.774(6) A, beta = 91.85(3) degrees, V = 3772(1) A(3).     

Mononitrosyl tris(thiolate) iron complex [Fe(NO)(SPh)3]- and dinitrosyl iron complex [(EtS)2Fe(NO)2]-: formation pathway of dinitrosyl iron complexes (DNICs) from nitrosylation of biomimetic rubredoxin [Fe(SR)4]2-/1- (R = Ph, Et)

Nitrosylation of the biomimetic reduced- and oxidized-form rubredoxin [Fe(SR)4]2-/1- (R = Ph, Et) in a 1:1 stoichiometry led to the formation of the extremely air- and light-sensitive mononitrosyl tris(thiolate) iron complexes (MNICs) [Fe(NO)(SR)3]- along with byproducts [SR]- or (RS)2. Transformation of [Fe(NO)(SR)3]- into dinitrosyl iron complexes (DNICs) [(RS)2Fe(NO)2]- and Roussin's red ester [Fe2(mu-SR)2(NO)4] occurs rapidly under addition of 1 equiv of NO(g) and [NO]+, respectively. Obviously, the mononitrosyl tris(thiolate) complex [Fe(NO)(SR)3]- acts as an intermediate when the biomimetic oxidized- and reduced-form rubredoxin [Fe(SR)4]2-/1- exposed to NO(g) were modified to form dinitrosyl iron complexes [(RS)2Fe(NO)2]-. Presumably, NO binding to the electron-deficient [Fe(III)(SR)4]- and [Fe(III)(NO)(SR)3]- complexes triggers reductive elimination of dialkyl/diphenyl disulfide, while binding of NO radical to the reduced-form [Fe(II)(SR)4]2- induces the thiolate-ligand elimination. Protonation of [Fe(NO)(SEt)3]- yielding [Fe(NO)(SPh)3]- by adding 3 equiv of thiophenol and transformation of [Fe(NO)(SPh)3]- to [Fe(NO)(SEt)3]- in the presence of 3 equiv of [SEt]-, respectively, demonstrated that complexes [Fe(NO)(SPh)3]- and [Fe(NO)(SEt)3]- are chemically interconvertible. Mononitrosyl tris(thiolate) iron complex [Fe(NO)(SPh)3]- and dinitrosyl iron complex [(EtS)2Fe(NO)2]- were isolated and characterized by X-ray diffraction. The mean NO bond distances of 1.181(7) A (or 1.191(7) A) in complex [(EtS)2Fe(NO)2]- are nearly at the upper end of the 1.178(3)-1.160(6) A for the anionic {Fe(NO)2}9 DNICs, while the mean FeN(O) distances of 1.674(6) A (or 1.679(6) A) exactly fall in the range of 1.695(3)-1.661(4) A for the anionic {Fe(NO)2}9 DNICs.