Synthesis and structural characterization of the luminescent tetranuclear complex [NBu4]2[(C6F5)6(μ-OH)3Pt3HgCl] with Pt-Hg bonds unsupported by covalent bridging ligands

The tetranuclear cluster [NBu4]2[(C6F5)6(-OH)3Pt3HgCl] is obtained by reacting the mononuclear platinum complex [NBu4]2[Pt(C6F5)3Cl] with Hg(NO3)2 followed by appropriate work-up. The X-ray study reveals that the compound possesses three donor-acceptor PtHg bonds unsupported by any covalent bridges. The crystallographic parameters are: monoclinic, P21/n with a=11.9770(10), b=26.092(3), c=24.991(2) Å, =92.900(10)°, Dcalc=2.009 Mg m-3 for Z=4 and R=0.076 utilizing 13 657 data with Fo22(Fo2). The UV-vis spectrum of the solid sample has been studied revealing that the compound is strongly luminescent. © 2000 Elsevier Science S.A

Building C(sp(3)) Molecular Complexity on 2,2 '-Bipyridine and 1,10-Phenanthroline in Rhenium Tricarbonyl Complexes

The reactions of [Re(N-N)(CO)(3)(PMe3)]OTf (N-N=2,2 '-bipyridine, bipy; 1,10-phenanthroline, phen) compounds with tBuLi and with LiHBEt3 have been explored. Addition to the N-N chelate took place with different site-selectivity depending on both chelate and nucleophile. Thus, with tBuLi, an unprecedented addition to C5 of bipy, a regiochemistry not accessible for free bipy, was obtained, whereas coordinated phen underwent tBuLi addition to C2 and C4. Remarkably, when LiHBEt3 reacted with [Re(bipy)(CO)(3)(PMe3)]OTf, hydride addition to the 4 and 6 positions of bipy triggered an intermolecular cyclodimerization of two dearomatized pyridyl rings. In contrast, hydride addition to the phen analog resulted in partial reduction of one pyridine ring. The resulting neutral Re-I products showed a varied reactivity with HOTf and with MeOTf to yield cationic complexes. These strategies rendered access to Re-I complexes containing bipy- and phen-derived chelates with several C(sp(3)) centers

Slow magnetic relaxations in a ladder-type Dy(III) complex and its dinuclear analogue

The complex {[Dy2(PDOA)3(H2O)6]·2H2O}n (1) (H2PDOA = 1, 2-phenylenedioxydiacetic acid) was prepared from aqueous solution. Its crystal structure, built up of {-Dy-O-C-O-}n chains interlinked by PDOA ligands yielding a ladder-like arrangement, was determined at 173 K. 1 exhibits slow magnetic relaxation under a small magnetic field BDC = 0.2 T with two (LF and HF) relaxation channels. The LF relaxation time at BDC = 0.2 T and T = 1.85 K is as slow as t(LF) = 46 ms whereas the HF channel is t(HF) = 1.4 ms. The mole fraction of the LF species is xLF = 0.76 at 1.85 K and it escapes progressively on heating. In the dinuclear analogue [Dy2(PDOA)3(H2O)6]·3.5H2O (2) one PDOA ligand forms a bis(chelate) bridge between the two Dy(iii) atoms yielding a local structure analogous to that in 1; however its AC susceptibility data show slightly different quantitative characteristics of the single-molecule magnetic behaviour

Field induced slow magnetic relaxation in a zig-zag chain-like Dy(iii) complex with the ligando-phenylenedioxydiacetato

The new complex [Dy(PDOA)(NO3)(H2O)(2)](n)center dot nH(2)O (1) (H(2)PDOA iso-phenylenedioxydiacetic acid) was isolated from the reaction of dysprosium(iii) nitrate and H(2)PDOA in a 1 : 1 molar ratio. Its crystal structure is formed of neutral zig-zag chains in which the nona-coordinated Dy(iii) atoms (O(9)donor set) are linked by PDOA ligands with a chelating-bridging coordination mode. DC and AC magnetic studies revealed that1behaves as a field-induced SMM with three relaxation channels. The derived values, considering the Orbach relaxation process, of the barrier to spin reversal and the extrapolated relaxation time areU/k(B)= 59.5 K and tau(0)= 6.3 x 10(-10)s, respectively.Ab initiocalculations support the experimental results

Stability of AgIII towards Halides in Organosilver(III) Complexes

The involvement of silver in two-electron AgI/AgIII processes is currently emerging. However, the range of stability of the required and uncommon AgIII species is virtually unknown. Here, the stability of AgIII towards the whole set of halide ligands in the organosilver(III) complex frame [(CF3)3AgX]- (X=F, Cl, Br, I, At) is theoretically analyzed. The results obtained depend on a single factor: the nature of X. Even the softest and least electronegative halides (I and At) are found to form reasonably stable AgIII-X bonds. Our estimates were confirmed by experiment. The whole series of nonradiative halide complexes [PPh4][(CF3)3AgX] (X=F, Cl, Br, I) has been experimentally prepared and all its constituents have been isolated in pure form. The pseudohalides [PPh4][(CF3)3AgCN] and [PPh4][(CF3)3Ag(N3)] have also been isolated, the latter being the first silver(III) azido complex. Except for the iodo compound, all the crystal and molecular structures have been established by single-crystal X-ray diffraction methods. The decomposition paths of the [(CF3)3AgX]- entities at the unimolecular level have been examined in the gas phase by multistage mass spectrometry (MSn). The experimental detection of the two series of mixed complexes [CF3AgX]- and [FAgX]- arising from the corresponding parent species [(CF3)3AgX]- demonstrate that the Ag-X bond is particularly robust. Our experimental observations are rationalized with the aid of theoretical methods. Smooth variation with the electronegativity of X is also observed in the thermolyses of bulk samples. The thermal stability in the solid state gradually decreases from X=F (145 °C, dec.) to X=I (78 °C, dec.) The experimentally established compatibility of AgIII with the heaviest halides is of particular relevance to silver-mediated or silver-catalyzed processes

Intramolecular C-C Coupling Reactions of Alkynyl, Vinylidene, and Alkenylphosphane Ligands in Rhodium(III) Complexes

Electrophilic attack with methyl trifluoromethanesulfonate or tetrafluoroboric acid, to new alkynyl rhodium complexes containing alkenylphosphanes, leads to butenynyl coupling products or to the unprecedented rhodaphosphacycle complexes Rh(¿5-C5Me5){¿4-(P, C, C, C)-iPr2PCH2C(=CH2)C(CH2R)C=C(R)}]BF4] (R = Ph (11a), p-tol (11b)). These complexes 11a, b can be explained as a result of the coupling of three organic fragments in the molecule, the alkynyl, the vinylidene, generated in situ by reaction with HBF4 (A), and the C-C double bond from the alkenylphosphane. DFT computational studies on the formation of complex 11a suggest the 2 + 2] intramolecular cycloaddition between the double bond of the allylphosphane and the Ca-Cß of the vinylidene A as the most plausible pathway for this reaction

Syntheses, crystal structures and magnetic properties of complexes based on [Ni(L-L)3]2+ complex cations with dimethylderivatives of 2, 2'-bipyridine and TCNQ

From the aqueous-methanolic systems Ni(NO3)2 – LiTCNQ – 5, 5'-dmbpy and Ni(NO3)2 – LiTCNQ – 4, 4'-dmbpy three novel complexes [Ni(5, 5'-dmbpy)3](TCNQ)2 (1), [Ni(4, 4'-dmbpy)3](TCNQ)2 (2) and [Ni(4, 4'-dmbpy)3]2(TCNQ-TCNQ)(TCNQ)2·0.60H2O (3), were isolated in single crystal form. The new compounds were identified using chemical analyses and IR spectroscopy. Single crystal studies of all samples corroborated their compositions and have shown that their ionic structures contain the complex cations [Ni(5, 5'-dmbpy)]2+ (1) or [Ni(4, 4'-dmbpy)]2+ (2 and 3). The anionic parts of the respective crystal structures 1–3 are formed by TCNQ·- anion-radicals and in 3 also by a s-dimerized dianion (TCNQ-TCNQ)2- with a C-C distance of 1.663(5) Å. The supramolecular structures are governed by weak hydrogen bonding interactions. The variable-temperature (2–300 K) magnetic studies of 1 and 3 confirmed the presence of magnetically active Ni(II) atoms with S = 1 and TCNQ·- anion-radicals with S = 1/2 while the (TCNQ-TCNQ)2- dianion is magnetically silent. The magnetic behavior was described by a complex magnetic model assuming strong antiferromagnetic interactions between some TCNQ·- anion-radicals

Diastereoselective synthesis of the indenylruthenium(II) complexes [Ru(η5-C9H7){κ3(P,C,C)- Ph2P(CH2CR=CH2)}(PPh3)][PF 6] (R = H, Me)

The stereoselective synthesis and reactivity of the mixed-phosphine complexes [Ru(η 5-C9H7){k 3(P,C,C)- Ph2P(CH2CR=CH2)}(PPh 3)][PF6] (R=H, Me) bearing the hybrid hemilabile ligand allyldiphenylphosphine were discussed. It was found that the reaction of R=H with sodium methoxide in methanol yielded the hybride derivative complexes. The olefin exchange occurred with regard to parallel first-order and second-order pathways. The ruthenium fragment acting as a Lewis acid with chiral recognition provides an appropriate means to envisage potential enantioselective transformations of prochiral olefins

Unusual bridging of the metal centers in a heterometallic titanium-platinum complex. X-ray structure of [Cp2Ti(mu2-eta1-C=CtBu)2Pt(C6F5)2]·CH2Cl2

The reaction between [Cp2Ti(CCtBu)2] (1) and [cis-Pt(C6F5)2(THF)2] gives the mixed complex [Cp2-Ti(2-1-CC tBu)2Pt(C6F5)2] (2), which has been shown by X-ray crystallography to contain a system of two asymmetric 2-1-alkynyl ligands bridging both metal centers. Complex 2 crystallizes as the dichloromethane solvate in the monoclinic crystal system, space group P21/n, with a = 133.725 (2) Å, b = 15.875 (2) Å, c = 16.424 (3) Å, = 99.58 (2)°, V = 3529 (1) Å3, and Z = 4. A model of 447 parameters was refined to 3586 diffraction data, giving residuals of R = 0.0390, Rw = 0.0558, and quality-of-fit = 1.367. The Pt-Ti distance is 2.831 (2) Å. © 1993 American Chemical Society