Fluorescent Orthopalladated Complexes of 4-Aryliden-5(4H)-oxazolones from the Kaede Protein: Synthesis and Characterization

The goal of the work reported here was to amplify the fluorescent properties of 4-aryliden-5(4H)-oxazolones by suppression of the hula-twist non-radiative deactivation pathway. This aim was achieved by simultaneous bonding of a Pd center to the N atom of the heterocycle and the ortho carbon of the arylidene ring. Two different 4-((Z)-arylidene)-2-((E)-styryl)-5(4H)-oxazolones, the structures of which are closely related to the chromophore of the Kaede protein and substituted at the 2- and 4-positions of the arylidene ring (1a OMe; 1b F), were used as starting materials. Oxazolones 1a and 1b were reacted with Pd(OAc)2 to give the corresponding dinuclear orthometalated palladium derivates 2a and 2b by regioselective C-H activation of the ortho-position of the arylidene ring. Reaction of 2a (2b) with LiCl promoted the metathesis of the bridging carboxylate by chloride ligands to afford dinuclear 3a (3b). Mononuclear complexes containing the orthopalladated oxazolone and a variety of ancillary ligands (acetylacetonate (4a, 4b), hydroxyquinolinate (5a), aminoquinoline (6a), bipyridine (7a), phenanthroline (8a)) were prepared from 3a or 3b through metathesis of anionic ligands or substitution of neutral weakly bonded ligands. All species were fully characterized and the X-ray determination of the molecular structure of 7a was carried out. This structure has strongly distorted ligands due to intramolecular interactions. Fluorescence measurements showed an increase in the quantum yield (QY) by up to one order of magnitude on comparing the free oxazolone (QY < 1%) with the palladated oxazolone (QY = 12% for 6a). This fact shows that the coordination of the oxazolone to the palladium efficiently suppresses the hula-twist deactivation pathway

Functionalization and Coordination Effects on the Structural Chemistry of Pendant Arm Derivatives of 1,4,7-trithia-10-aza-cyclododecane ([12]aneNS3)

The effect of different pendant arms on the structural chemistry of the 1,4,7-trithia-10-aza-cyclododecane ([12]aneNS3) macrocycle is discussed in relation to the coordination chemistry of all known functionalized derivatives of [12]aneNS3, which have been structurally characterized

Phenylmercury(II) derivatives of tetraorganodichalcogenoimidodiphosphorus acids. Crystal and molecular structure of PhHg{(OPR2)(SPPh2)N} (2) (R = Me, Ph)

The reactions between PhHgCl or PhHgAc and M[(XPR2)(YPR2')N] (M = Na, K; X, Y = O, S; R, R' = Me, Ph, OEt), in 1:1 molar ratio, have been investigated. PhHg[(XPR2)(YPR2')N] derivatives were isolated as microcrystalline powders and were characterised using IR and NMR (H-1, C-13 and P-31) spectroscopy and mass spectrometry. The molecular structure of PhHg[(OPR2)(SPPh2)N] [R = Me (1), Ph (2)] was investigated by X-ray diffraction. In the monomeric unit, PhHg[(OPR2)(SPPh2)N], the mercury atom forms the primary bonds with the carbon of the phenyl group and the sulfur atom of the phosphorus ligand [Hg(1)-S(1) 2.405(1) Angstrom for 1, 2.398(2) Angstrom for 2]. These primary bonds are significantly deviated from the expected linear arrangement [C(1)-Hg(1)-S(1) 166.4(2)degrees for 1, 165.0(2)degrees for 2]. Both compounds exhibit dimeric associations in the crystal through S,O-bridging organophosphorus ligands [Hg(1)-O(1) 2.556(4) Angstrom for 1, 2.588(4) Angstrom for 2], thus resulting in a distorted T-shaped arrangement of the CHgSO coordination core.. The formation of a 12-membered Hg2O2S2P4N2 ring with different conformation in 1 and 2, respectively, results in different additional chalcogen atoms being in the proximity of the metal atom. Weak transannular (HgO)-O-... [2.753(4) Angstrom] are also established in 1, leading to a tricyclic ladder structure with a planar central Hg2O2 ring

Structural diversity of cadmium(II) complexes of tetraorganodichalcogenoimidodiphosphinato ligands: Monomeric Cd (SPMe2)(2)N (2), dinuclear Cd{(OPMe2)(SPPh2)N}(2) (2) and Cd-2{(OPPh2)(2)N}(4)(H2O) , and trinuclear K Cd-2{(OPPh2)(2)N}(5)

`Cadmium complexes of the type Cd[(XPR2)(YPR'2)N](2) (X, Y = O, S; R, R' = Me, Ph) were obtained by reacting CdCl2 and K[(XPR2)(YPR'2)N] in a 1:2 molar ratio. The compounds were characterized by IR, multinuclear NMR (H-1, C-13, P-31) spectroscopy and mass spectrometry. The molecular structures of Cd[(SPMe2)(2)N](2) (1), Cd[(OPMe2)(SPPh2)N](2) (4), Cd-2{(OPPh2)(2)N}(4)(H2O)](7 center dot H2O) and K[Cd-2{(OPPh2)(2)N)(5)] (8) were established by single-crystal X-ray diffraction. Colourless crystals of 8 were isolated, along with those of 7-H2O, during recrystallization of crude Cd[(OPPh2)(2)N](2) (7). A monomeric structure with a tetrahedral CdS4 core is found for 1, whereas 4 contains discrete dimers formed through two O,O', S-bimetallictriconnective ligand units resulting in distorted trigonal bipyramidal CdO3S2 Cores. In the dinuclear compound 7 center dot H2O the Cd atoms are also bridged by two O, O', O'-bimetallic triconnective ligands, but the coordination of the metal centres is completed by a bridging water molecule to give distorted octahedral CdO6 cores. in the trimetallic unit of 8 the K atom is accommodated in the cavity described by the oxygen atoms of three ligand units which bridge the Cd atoms. The remaining two ligands are each one chelating a Cd atom, thus resulting in distorted square pyramidal CdO5 cores

Organoselenium(II) halides containing the pincer 2,6-(Me2NCH2)2C6H3 ligand – an experimental and theoretical investigation

New organoselenium(II) halides of the type [RSe]+X− [R = 2,6-(Me2NCH2)2C6H3; X = Cl (2), Br (3), I (4)] were prepared by cleavage of the Se–Se bond in R2Se2 (1) with SO2Cl2 followed by halogen exchange when organoselenium chloride was treated with NaBr or KI. The reaction between 2 and R’2MCln resulted in new ionic [RSe]+[R’2MCln+1]− [R’ = 2-(Me2NCH2)C6H4, n = 1, M = Sb (5), Bi (6); R’ = Ph, M = Sb, n = 1 (7) or n = 3 (8)] species. All new compounds were investigated in solution by multinuclear NMR spectroscopy (1H, 13C, 77Se, 2D experiments) and mass spectrometry. The ionic nature of 2 and the antimonates species was confirmed by conductivity studies. The molecular structures of [{2,6-(Me2NCH2)2C6H3}Se]+Cl−·nH2O (2·H2O and 2·2H2O) and [{2,6-(Me2NCH2)2C6H3}Se]+[Ph2SbCl4]− (8), respectively, were established by single-crystal X-ray diffraction, pointing out that the ionic nature of these compounds is also preserved in the solid state, with both nitrogen atoms strongly trans coordinated to the selenium atom of the cation. Theoretical calculations carried out at the DFT level were exploited to investigate the nature of the bonding in compounds 2–4 and the free cation [RSe]+ (2a). A topological analysis based on the theory of Atoms-In-Molecules (AIM) and Electron Localization Function (ELF) jointly to a Natural Bond Orbital (NBO) approach was used to shed light on the effect of the nature of the halogen species X on the bonding within the 3c-4e N–Se–Nmoiety

Organoselenium(II) and selenium(IV) compounds containing 2-(Me2NCH2)C6H4 moieties: solution behavior and solid state structure

The cleavage of the Se-Se bond in [2-(Me2NCH2)C6H4]2Se2 (1) was achieved by treatment with SO2Cl2 (1:1 molar ratio) or elemental halogens to yield [2-(Me2NCH-)C6H4]SeX [X = Cl (2), Br (3), I (4)]. Oxidation of 1 with SO2Cl2 (1:3 molar ratio) gave [2-(Me2NCH2)C6H4]SeCl3 (5). [2-(Me2NCH2)C6H4]SeS(S)CNR2 [R = Me (6), Et (7)] were prepared by reacting [2-(Me2NCH2)C6H4]SeBr with Na[S2CNR2] . nH2O (R = Me, n = 2; R = Et, n = 3). The reaction of 3 with K[(SPMe2)(SPPh2)N] resulted in isolation of [2-(Me2NCH2)C6H4]Se-S-PMe2=N-PPh2=S (8). The compounds were characterized by solution NMR spectroscopy (1H, 13C, 31P, 77Se, 2D experiments). The solid-state molecular structures of 2, 4-8 were established by single crystal X-ray diffraction. All compounds are monomeric, with the N atom of the pendant CH2NMe2 arm involved in a three-center-four-electron N •••Se-X (X = halogen, S) bond. This results in a T-shaped coordination geometry for the Se(II) atom in 2, 4, 6-8. In 5, the Se(IV) atom achieves a square pyramidal coordination in the mononuclear unit. Loosely connected dimers are formed through intermolecular Se•••Cl interactions (3.40 angstrom); the overall coordination geometry being distorted octahedral. In all compounds hydrogen bonds involving halide or sulfur atoms generate supramolecular associations in crystals

Synthesis, spectroscopic characterization, and structural studies of new Cu(I) and Cu(II) complexes containing organophosphorus ligands, and crystal structures of (Ph3P)(2)Cu S2PMe2 , (Ph3P)(2)Cu (OPPh2)(2)N , Cu (OPPh2)(2)N (2), and Cu (OPPh2)(SPPh2)N (2)

The Cu(I) complexes, (Ph3P)(2)CuL (L = [S2PMe2](-), [OSPR2](-) (R = Me, Ph), [(XPR2)(YPR'(2))N](-) (X, Y, R, R' = O, O, Ph, Ph; O, S, Ph, Ph; O, S, OEt, Ph; S, S, Me, Me)) and Cu(II) complexes, CuL2 (L = [(XPR2)(YPR'(2))N](-) (X, Y, R, R' = O, O, Ph, Ph; O, S, Ph, Ph)), have been prepared. The Cu(I) derivatives were characterized by multinuclear NMR spectroscopy and in two cases by X-ray crystallography. (Ph3P)(2)Cu[S2PMe2] (1) crystallizes in the orthorhombic space group P2(1)2(1)2(1) (No. 19) with cell parameters a = 9.782(2), b = 17.808(4), c = 20.216(4) Angstrom, V = 3521(6) Angstrom (3) and Z = 4, and (Ph3P)(2)Cu[(OPPh2)(2)N] (4) in the triclinic space group P (1) over bar (No. 2) with cell parameters a = 9.8079(2), b = 12.9141(3), c = 22.5666(5) Angstrom, alpha = 75.714(2), beta = 79.465(2), gamma = 68.2770(8)degrees, V = 2559.9(1) Angstrom (3) and Z = 2. In both cases the phosphorusligands are bidentate, thus resulting in monomeric molecules that contain tetrahedral CuP2S2 and CuP2O2 cores. The molecular structures of two of the Cu(II) derivatives were also determined. Cu[(OPPh2)(2)N](2) (8) and Cu[(OPPh2)(SPPh2)N](2) (9) crystallize in the triclinic space groupP (1)over bar (No. 2) with cell parameters a = 8.887(2), b = 10.739(2), c = 12.477(3) Angstrom, alpha = 77.61(3), beta = 76.15(5), gamma = 79.46(3)degrees,V = 1118.3(4) Angstrom (3) and Z = 1 for 8, and a = 9.626(2), b = 14.151(3), c = 24.752(5) Angstrom, alpha = 88.23(3), beta = 79.93(3), gamma = 89.77(3)degrees, V = 3181(1) Angstrom (3) and Z = 3 for 9. The moleculeof Cu[(OPPh2)(2)N](2) (8) has a planar CuO4 core, while in Cu[(OPPh2)(SPPh2)N](2) (9) both planar and tetrahedral copper cores are observed in a ratio of 1:2