Diorganodiselenides and zinc(II) organoselenolates containing (imino)aryl groups of type 2-(RN=CH)C6H4

Several new diorganodiselenides containing (imino)aryl groups, [2-(RN[double bond, length as m-dash]CH)C(6)H(4)](2)Se(2) [R = Me(2)NCH(2)CH(2) (4), O(CH(2)CH(2))(2)NCH(2)CH(2) (5), PhCH(2) (6), 2',6'-(i)Pr(2)C(6)H(3) (7)] were obtained by reacting [2-{(O)CH}C(6)H(4)](2)Se(2) (3) with RNH(2). Treatment of the diselenides 6 and 7 with stoichiometric amounts of K-selectride or Na resulted in isolation of the selenolates K[SeC(6)H(4)(CH[double bond, length as m-dash]NCH(2)Ph)-2] (9) and Na[SeC(6)H(4)(CH[double bond, length as m-dash]NC(6)H(3)(i)Pr(2)-2',6')-2] (10), respectively. The reaction of potassium selenolates with anhydrous ZnCl(2) (2:1 molar ratio) gave Zn[SeC(6)H(4)(CH=NCH(2)Ph)-2](2) (11) and Zn[SeC(6)H(4)(CH[double bond, length as m-dash]NC(6)H(3)(i)Pr(2)-2',6')-2](2) (12). When the dark green solution obtained from diselenide 7 and an excess of Na (after removal of the unreacted metal) was reacted with anhydrous ZnCl(2) a carbon-carbon coupling reaction occurred and the 9,10-(2',6'-(i)Pr(2)C(6)H(3)NH)(2)C(14)H(10) (8) species was obtained. The compounds were investigated in solution by multinuclear NMR ((1)H, (13)C, (77)Se, including 2D and variable temperature experiments) and by mass spectrometry. The molecular structures of 6, 8, 11 and 12 were established by single-crystal X-ray diffraction. All compounds are monomeric in the solid state. In the diselenide 6 the (imino)aryl group acts as a (C,N)-ligand resulting in a distorted T-shaped coordination geometry of type (C,N)SeX (X = Se). For the zinc complexes 11 and 12 the (Se,N) chelate pattern of the selenolato ligands results in tetrahedral Zn(Se,N)(2) cores.     

Solid state structure and solution behaviour of organoselenium(II) compounds containing 2-{E(CH2CH2)2NCH2}C6H4 groups (E = O, NMe)

Cleavage of the Se-Se bond in [2-{O(CH(2)CH(2))(2)NCH(2)}C(6)H(4)](2)Se(2) (1) and [2-{MeN(CH(2)CH(2))(2)NCH(2)}C(6)H(4)](2)Se(2) (2) by treatment with SO(2)Cl(2), bromine or iodine (1 : 1 molar ratio) yielded [2-{O(CH(2)CH(2))(2)NCH(2)}C(6)H(4)]SeX [X = Cl (3), Br (4), I (5)] and [2-{MeN(CH(2)CH(2))(2)NCH(2)}C(6)H(4)]SeI (6). The compounds were characterized in solution by NMR spectroscopy (1H, 13C, 15N, 77Se, 2D experiments). The solid-state molecular structures of 1-3, 4.HBr, 5 and 6 were established by single crystal X-ray diffraction. In all cases T-shaped coordination geometries, i.e. (C,N)SeSe (1, 2), (C,N)SeX (3, 5, 6; X = halogen) or CSeBr(2) (4.HBr), were found. Supramolecular associations in crystals based on hydrogen contacts are discussed.     

EPR study on the ligand-exchange reaction between bis(diethyldiselenocarbamato)copper(II) and bis(octyldithiocarbonato)copper(II)

EPR study on the ligand-exchange reaction between bis(diethyldiselenocarbamato)copper(II), Cu(Et2dsc)2, and bis(octyldithiocarbonato)copper(II), Cu(octxant)2, in CH2Cl2, CHCl3, CCl4, C6H6 and C6H5.CH3 is reported for the first time. Mixing of equimolar amounts of the parents (chromophores CuSe4 and CuS4, respectively) in C6H6, C6H5.CH3 and CH2Cl2 makes EPR signals of both parents superimposed by the spectrum of a mixed-chelate Cu(xant)(dsc) complex (chromophore CuS2Se2). A new additional EPR spectrum appears in CHCl3 or CCl4 due to a five-coordinate mixed-ligand complex with the chromophore Cu(S3Se)S as follows by comparing the g-values of parents and mixed-ligand complexes. The appearance of this complex could be explained having in mind donor-acceptor properties of complexes, solvents and the resultant reaction of Cu(octxant)2 with the ester of diselenocarbamic acid yielded in Cu(Et2dsc)2 destruction by CCl4 or CHCl3.     

A microwave spectroscopic and quantum chemical study of propa-1,2-dienyl selenocyanate (H(2)==C==CHSeC[triple bond]N) and cyclopropyl selenocyanate (C(3)H(5)SeC[triple bond]N)

The microwave spectra of propa-1,2-dienyl selenocyanate, H(2)C==C==CHSeC[triple bond]N, and cyclopropyl selenocyanate, C(3)H(5)SeC[triple bond]N, are reported. The spectra of the ground and two vibrationally excited states of the (80)Se isotopologue and the spectrum of the ground state of the (78)Se isotopologue were assigned for one rotameric form of H(2)C==C[double bond, length as m-dash]CHSeC[triple bond]N. This conformer is characterized by a C-C-Se-C dihedral angle of 129(5) degrees from synperiplanar (0 degrees ) and is shown to be the global minimum of H(2)C[double bond, length as m-dash]C[double bond, length as m-dash]CHSeC[triple bond]N. The spectra of the ground and of three vibrationally excited states of the (80)Se isotopologue, as well as of the ground state of the (78)Se isotopologue of one rotamer of C(3)H(5)SeC[triple bond]N were assigned. This conformer has a H-C-Se-C dihedral angle of 80(4) degrees from synperiplanar and is at least 3 kJ mol(-1) more stable than any other form of the molecule. The microwave study has been augmented by quantum chemical calculations at the B3LYP/6-311+ +G(3df,3pd) and MP2/6-311+ +G(3df,3pd) levels of theory.     

Complexation of Zn(II), Cd(II) and Hg(II) with thiourea and selenourea: A 1H, 13C, 15N, 77Se and 113Cd solution and solid-state NMR study

Zinc(II), cadmium(II) and mercury(II) complexes of thiourea (TU) and selenourea (SeU) of general formula M(TU)₂Cl₂ or M(SeU)₂Cl₂ have been prepared. The complexes were characterized by elemental analysis and NMR (¹H, ¹³C, ¹⁵N, ⁷⁷Se and ¹¹³Cd) spectroscopy. A low-frequency shift of the C=S resonance of thiones in ¹³C NMR and high-frequency shifts of N–H resonances in ¹H and ¹⁵N NMR are consistent with sulfur or selenium coordination to the metal ions. The Se nucleus in Cd(SeU)₂Cl₂ in ⁷⁷Se NMR is deshielded by 87?ppm on coordination, relative to the free ligand. In comparison, the analogous Zn(II) and Hg(II) complexes show deshielding by 33 and 50?ppm, respectively, indicating that the orbital overlap of Se with Cd is better. Principal components of ⁷⁷Se and ¹¹³Cd shielding tensors were determined from solid-state NMR data.     

Synthesis and structure of mercurous ion and dinuclear lead(II) complexes of the 28-membered selenaaza macrocycle: dominance of the chelate ring size effect and conformational requirement over soft-soft interactions

The flexible and larger ring size macrocycle 4 (C(36)H(46)N(6)Se(2)) afforded stable complex 5 [Hg(2)(PF(6))(2)[C(36)H(46)N(6)Se(2)]] on treatment with 1 equiv of mercuric acetate followed by addition of NH(4)PF(6). The reaction of Pb(OCOCH(3))(2).4H(2)O with 4 followed by treatment with NH(4)PF(6) resulted in a dinuclear lead complex (6) [Pb(2)(PF(6))(2)(OCOCH(3))(2)[C(36)H(46)N(6)Se(2)]]. The crystal structures of complexes 5 and 6 are described: C(36)H(46)F(12)Hg(2)N(6)P(2)Se(2) a = 9.5106(5) A, b = 11.5222(6) A, c = 11.8161(6) A, alpha = 115.6110(10) degrees , beta = 96.5190(10) degrees , gamma = 106.2910(10) degrees , monoclinic, P, Z =1; C(44)H(57)F(12)N(8)O(4)P(2)Pb(2)Se(2) a = 9.4668(5) A, b = 11.9937(6) A, c = 25.2319(14) A, alpha = 102.4130(10) degrees , beta = 97.6130(10) degrees , gamma = 94.8540(10) degrees , monoclinic, P, Z = 2. The crystal structure of 5 revealed that Hg(2)(2+) is trapped inside the cavity of the macrocycle. The geometry around the mercurous ion is antiprismatic with Hg(2)(2+) coordinating to six nitrogen atoms forming four five-membered rings, and there is no interaction between the mercurous ion and the selenium donor atoms. The single crystal X-ray crystal structure of 6 indicates a distorted octahedral geometry around each lead atom in the cavity of the macrocycle due to presence of the sterochemically active lone pair on Pb(II). The octahedral geometry around each Pb(II) is satisfied by coordination to 3 nitrogen atoms, two oxygen atoms of the chelating acetate group, and bridging of one of the oxygen atoms of the nearby acetate.     

Coordination Chemistry of 2,2'-Dipyridyl Diselenide: X-ray Crystal Structures of PySeSePy, [Zn(PySeSePy)Cl(2)], [(PySeSePy)Hg(C(6)F(5))(2)], [Mo(SePy)(2)(CO)(3)], [W(SePy)(2)(CO)(3)], and [Fe(SePy)(2)(CO)(2)] (PySeSePy = C(5)H(4)NSeSeC(5)H(4)N; SePy = [C(5)H(4)N(2-Se)-N,Se])

The coordination chemistry of 2,2'-dipyridyl diselenide (PySeSePy) (2) (C(10)H(8)N(2)Se(2)) has been investigated and its crystal structure has been determined (monoclinic, P2(1)/c, a = 10.129(2) ?, b = 5.7332(12) ?, c = 19.173(3) ?, beta = 101.493(8) degrees, Z = 4). In metal complexes the ligand was found to coordinate in three different modes, as also confirmed by X-ray structure determination. N,N'-coordination was found in the zinc complex [Zn(PySeSePy)Cl(2)] (3) (C(10)H(8)Cl(2)N(2)Se(2)Zn, triclinic, P&onemacr;, a = 7.9430(10) ?, b = 8.147(2) ?, c = 11.999(2) ?, alpha = 93.685(10) degrees, beta = 107.763(10) degrees, gamma = 115.440(10) degrees, Z = 2) and Se,Se'-coordination in the adduct of the ligand with bis(pentafluorophenyl)mercury(II) [PySeSePyHg(C(6)F(5))(2)] (5) (C(10)H(8)F(10)HgN(2)Se(2), monoclinic, P2(1)/n, a = 7.7325(10) ?, b = 5.9974(14) ?, c = 25.573, beta = 98.037(10) degrees, Z = 2), which however displays only weak interactions between selenium and mercury. The reaction of the ligand with norbornadiene carbonyl complexes of molybdenum and tungsten leads to reductive cleavage of the selenium-selenium bond with oxidation of the metal center and concomitant addition of the resulting selenolate to the metal carbonyl fragment. Thus the 7-coordinate complexes [Mo(SePy)(2)(CO)(3)] (6) (C(13)H(8)MoN(2)O(3)Se(2), monoclinic, P2(1)/n, a = 9.319(3) ?, b = 12.886(5) ?, c = 13.231(6) ?, beta = 109.23(3) degrees, Z = 4) and [W(SePy)(2)(CO)(3)] (7) (C(13)H(8)N(2)O(3)Se(2)W, monoclinic, P2(1)/n, a = 9.303(2) ?, b = 12.853(2) ?, c = 13.232(2) ?, beta = 109.270(10) degrees, Z = 4) were obtained. The same N,Se-coordination pattern emerges from the reaction of [Fe(2)(CO)(9)] with (2) leading to [Fe(SePy)(2)(CO)(2)] (8) (C(12)H(8)FeN(2)O(2)Se(2), monoclinic, P&onemacr;, a = 8.6691(14) ?, b = 12.443(2) ?, c = 14.085(2) ?, alpha = 105.811(10) degrees, beta = 107.533(8) degrees, gamma = 92.075(10) degrees, Z = 4).     

Ruthenium(II) ammine and hydrazine complexes with [N(Ph2PQ)2]- (Q = S, Se) ligands

Reactions of coordinatively unsaturated Ru[N(Ph2PQ)2]2(PPh3) (Q = S (1), Se (2)) with pyridine (py), SO2, and NH3 afford the corresponding 18e adducts Ru[N(Ph2PQ)2]2(PPh3)(L) (Q = S, L = NH3 (5); Q = Se, L = py (3), SO2 (4), NH3 (6)). The molecular structures of complexes 2 and 6 are determined. The geometry around Ru in 2 is pseudo square pyramidal with PPh3 occupying the apical position, while that in 6 is pseudooctahedral with PPh3 and NH3 mutually cis. The Ru-P distances in 2 and 6 are 2.2025(11) and 2.2778(11) A, respectively. The Ru-N bond length in 6 is 2.185(3) A. Treatment of 1 or 2 with substituted hydrazines L or NH2OH yields the respective adducts Ru[N(Ph2PQ)2]2(PPh3)(L) (Q = S, L = NH2NH2 (12), t-BuNHNH2 (14), l-aminopiperidine (C5H10NNH2) (15); Q = Se, L = PhCONHNH2 (7), PhNHNH2 (8), NH2OH (9), t-BuNHNH2 (10), C5H10NNH2 (11), NH2NH2 (13)), which are isolated as mixtures of their trans and cis isomers. The structures of cis-14 and cis-15 are characterized by X-ray crystallography. In both molecular structures, the ruthenium adopts a pseudooctahedral arrangement with PPh3 and hydrazine mutually cis. The Ru-N bond lengths in cis-14.CH2Cl2 and cis-15 are 2.152(3) and 2.101(3) A, respectively. The Ru-N-N bond angles in cis-14.CH2Cl2 and cis-15 are 120.5(4) and 129.0(2) degrees, respectively. Treatment of 1 with hydrazine monohydrate leads to the isolation of yellow 5 and red trans-Ru[N(Ph2PS)2]2(NH3)(H2O) (16), which are characterized by mass spectrometry, 1H NMR spectroscopy, and elemental analyses. The geometry around ruthenium in 16 is pseudooctahedral with the NH3 and H2O ligands mutually trans. The Ru-O and Ru-N bond distances are 2.118(4) and 2.142(6) A, respectively. Oxidation reactions of the above ruthenium hydrazine complexes are also studied.     

Synthesis, structure, and thermal properties of soluble hydrazinium germanium(IV) and tin(IV) selenide salts

The crystal structures of two hydrazinium-based germanium(IV) and tin(IV) selenide salts are determined. (N(2)H(5))(4)Ge(2)Se(6) (1) [I4(1)cd, a = 12.708(1) Angstroms, c = 21.955(2) Angstroms, Z = 8] and (N(2)H(4))(3)(N(2)H(5))(4)Sn(2)Se(6) (2) [P, a = 6.6475(6) Angstroms, b = 9.5474(9) Angstroms, c = 9.8830(10) Angstroms, alpha = 94.110(2) degrees, beta = 99.429(2) degrees, gamma = 104.141(2) degrees, Z = 1] each consist of anionic dimers of edge-sharing metal selenide tetrahedra, M(2)Se(6)(4-) (M = Ge or Sn), separated by hydrazinium cations and, for 2, additional neutral hydrazine molecules. Substantial hydrogen bonding exists among the hydrazine/hydrazinium molecules as well as between the hydrazinium cations and the selenide anions. Whereas the previously reported tin(IV) sulfide system, (N(2)H(5))(4)Sn(2)S(6), decomposes cleanly to microcrystalline SnS(2) when heated to 200 degrees C in an inert atmosphere, higher temperatures (>300 degrees C) are required to dissociate selenium from 1 and 2 for the analogous preparations of single-phase metal selenides. The metal chalcogenide salts are highly soluble in hydrazine, as well as in a variety of amines and DMSO, highlighting the potential usefulness of these compounds as precursors for the solution deposition of the corresponding metal chalcogenide films.     

Synthesis and structural characterization of a new series of vanadoselenites, [Se(x)V(4-x)O(12-x)](4-x)- (x=1,2)

Two new vanadoselenites, [SeV(3)O(11)](3)(-) and [Se(2)V(2)O(10)](2)(-), were synthesized by reacting SeO(2) with VO(3)(-). Single-crystal X-ray structural analyses of [(n-C(4)H(9))(4)N](3)[SeV(3)O(11)].0.5H(2)O [orthorhombic, space group P2(1)2(1)2, a = 22.328(5) A, b = 44.099(9) A, c = 12.287(3) A, Z = 8] and [[(C(6)H(5))(3)P](2)N](2)[Se(2)V(2)O(10)] [monoclinic, space group P2(1)/n, a = 12.2931(3) A, b = 13.5101(3) A, c = 20.9793(5) A, beta = 106.307(1) degrees, Z = 2] revealed that both anions are composed of Se(x)()V(4)(-)(x)()O(4) rings. The (51)V, (77)Se, and (17)O NMR spectra established that both [SeV(3)O(11)](3)(-) and [Se(2)V(2)O(10)](2)(-) anions maintain this ring structure in solution.     

A New Family of Chalcogen Bearing Macrocycles: Synthesis and Characterization of N 4 O 2 E 2 (E = Se,Te) Type Compounds

A new series of 24- and 28-membered macrocyclic systems associated with "hard" (N and O) and "soft" (Se or Te) donor atoms have been developed via template free (2 + 2) condensation reactions of bis(aminoalkyl)selenides/tellurides, {NH 2 (CH 2 ) n } 2 E (E = Se, Te; n = 2,3) with 2,6-diacetyl-4-methylphenol. A macroacycle, Se{(CH 2 ) 2 N=C(CH 3 )C 6 H 2 (OH)(CH 3 )C=O(CH 3 )} 2 , has also been obtained. These compounds have been characterized by ESMS, IR, and 1 H, 13 C, and 77 Se NMR spectroscopy.     

Preparation and x-ray structures of alkali-metal derivatives of the ambidentate anions [tBuN(E)P(mu-NtBu)2P(E)NtBu]2- (E = S, Se) and [tBuN(Se)P(mu-NtBu)2PN(H)tBu)]-

The ambidentate dianions [(t)BuN(E)P(mu-N(t)Bu)(2)P(E)N(t)Bu](2)(-) (5a, E = S; 5b, E = Se) are obtained as their disodium and dipotassium salts by the reaction of cis-[(t)Bu(H)N(E)P(mu-N(t)Bu)(2)P(E)N(H)(t)Bu] (6a, E = S; 6b, E = Se), with 2 equiv of MN(SiMe(3))(2) (M = Na, K) in THF at 23 degrees C. The corresponding dilithium derivative is prepared by reacting 6a with 2 equiv of (t)BuLi in THF at reflux. The X-ray structures of five complexes of the type [(THF)(x)()M](2)[(t)BuN(E)P(mu-N(t)Bu)(2)P(E)N(t)Bu] (9, M = Li, E = S, x = 2; 11a/11b, M = Na, E = S/Se, x = 2; 12a, M = K, E = S, x = 1; 12b, M = K, E = Se, x = 1.5) have been determined. In the dilithiated derivative 9 the dianion 5a adopts a bis (N,S)-chelated bonding mode involving four-membered LiNPS rings whereas 11a,b and 12a,b display a preference for the formation of six-membered MNPNPN and MEPNPE rings, i.e., (N,N' and E,E')-chelation. The bis-solvated disodium complexes 11a,b and the dilithium complex 9 are monomeric, but the dipotassium complexes 12a,b form dimers with a central K(2)E(2) ring and associate further through weak K.E contacts to give an infinite polymeric network of 20-membered K(6)E(6)P(4)N(4) rings. The monoanions [(t)Bu(H)N(E)P(mu-N(t)Bu)(2)P(E)N(t)Bu)](-) (E = S, Se) were obtained as their lithium derivatives 8a and 8b by the reaction of 1 equiv of (n)BuLi with 6a and 6b, respectively. An X-ray structure of the TMEDA-solvated complex 8a and the (31)P NMR spectrum of 8b indicate a N,E coordination mode. The reaction of 6b with excess (t)BuLi in THF at reflux results in partial deselenation to give the monolithiated P(III)/P(V) complex [(THF)(2)Li[(t)BuN(Se)P(mu-N(t)Bu)(2)PN(H)(t)Bu]] 10, which adopts a (N,Se) bonding mode.     

Redox chemistry of tellurium bis(tert-butylamido)cyclodiphosph(V)azane disulfide and diselenide systems: a spectroscopic and structural study

The redox chemistry of tellurium-chalcogenide systems is examined via reactions of tellurium(IV) tetrachloride with Li[(t)()BuN(E)P(mu-N(t)Bu)(2)P(E)N(H)(t)Bu] (3a, E = S; 3b, E = Se). Reaction of TeCl(4) with 2 equiv of 3a in THF generates the tellurium(IV) species TeCl(3)[HcddS(2)][H(2)cddS(2)] 4a [cddS(2) = (t)BuN(S)P(mu-N(t)Bu)(2)P(S)N(t)Bu] at short reaction times, while reduction to the tellurium(II) complex TeCl(2)[H(2)cddS(2)](2) 5a is observed at longer reaction times. The analogous reaction of TeCl(4) and 3b yields only the tellurium(II) complex TeCl(2)[H(2)cddSe(2)](2) 5b. The use of 4 equiv of 3a or 3b produces Te[HcddE(2)](2) (6a (E = S) or 6b (E = Se)). NMR and EPR studies of the 5:1 reaction of 3a and TeCl(4) in THF or C(6)D(6) indicate that the formation of the Te(II) complex 6a via decomposition of a Te(IV) precursor occurs via a radical process to generate H(2)cddS(2). Abstraction of hydrogen from THF solvent is proposed to account for the formation of 2a. These results are discussed in the context of known tellurium-sulfur and tellurium-nitrogen redox systems. The X-ray crystal structures of 4a.[C(7)H(8)](0.5), 5a, 5b, 6a.[C(6)H(14)](0.5), and 6b.[C(6)H(14)](0.5) have been determined. The cyclodiphosph(V)azane dichalcogenide ligand chelates the tellurium center in an E,N (E = S, Se) manner in 4a.[C(7)H(8)](0.5), 6a.[C(6)H(14)](0.5), and 6b.[C(6)H(14)](0.5) with long Te-N bond distances in each case. Further, a neutral H(2)cddS(2) ligand weakly coordinates the tellurium center in 4a small middle dot[C(7)H(8)](0.5) via a single chalcogen atom. A similar monodentate interaction of two neutral ligands with a TeCl(2) unit is observed in the case of 5a and 5b, giving a trans square planar arrangement at tellurium.     

Synthesis and structures of beta-diketiminatotin(II) halides, an amide and of Sn(=E)[{N(R)C(Ph)}2CH](NR2) (E = S or Se, R = SiMe3)

Treatment of [Li(L1)]2 (1) or K(L2) (2) with SnX2 in Et2O yielded the heteroleptic beta-diketiminatotin(II) halides Sn(L1)Cl (3a), Sn(L1)Br (3b) or Sn(L2)Cl (4), even when an excess of the alkali metal beta-diketiminate was used [L1={N(R)C(Ph)}2CH, L2={N(R)C(Ph)CHC(But)N(R)}, R = SiMe3]. From and half an equivalent each of SnCl2.2H2O and SnCl2, or one equivalent of SnCl2.2H2O, the product was Sn(L3)Cl (5) or Sn(L4)Cl (6), in which one or both of the N-R bonds of L1 had been hydrolytically cleaved; the compound Sn(L5)Cl (7) was similarly obtained from and an equivalent portion of SnCl2.2H2O [L3={N(R)C(Ph)CHC(But)N(H)}, L4={N(H)C(Ph)CHC(But)N(H)} and L5={N(H)C(Ph)}2CH]. The halide exchange between 3a and 3b, studied by two-dimensional (119)Sn{1H}-NMR spectroscopy, is attributed to implicate a (mu-Cl)(mu-Br)-dimeric intermediate or transition state. The 13C{1H}-NMR spectra of or showed two distinct resonances for each group, which coalesced on heating, corresponding to DeltaG(338 K)= 69.4 (3a) or 72.8 (3b) kJ mol(-1). The chloride ligand of was readily displaced by treatment with NaNR2, CF3SO3H or CH2(COPh)2, yielding Sn(L1)X [X = NR2 (8), O3SCF3 (9) or {OC(Ph)}2CH (10)]. Oxidative addition of sulfur or selenium to gave the tin(IV) terminal chalcogenides Sn(E)(L1)(NR2)[E = S (11) or Se (12)]. The X-ray structures of the cocrystal of 3a/3b and of the crystalline compounds 5, 6, 8, 11 and are presented, as well as multinuclear NMR spectra of each of the new compounds.     

Synthesis and structure of tetranuclear orthometallated Pd(II) complexes derived from bis-iminophosphoranes

The reaction of Pd(OAc)2 with bis-iminophosphoranes Ph3P=NCH2CH2CH2N=PPh3 (1a), [C6H4(C(O)N=PPh3)2-1,3] (1b) and [C6H4(C(O)N=PPh3)2-1,2] (1c), gives the orthopalladated tetranuclear complexes [{Pd(mu-Cl){C6H4(PPh2=NCH2-kappa-C,N)-2}}2CH2]2 (2a) [{Pd(mu-OAc){C6H4(PPh2=NC(O)-kappa-C,N)-2}}2C6H4-1',3']2 (2b) and [{Pd(mu-OAc){C6H4(PPh2=NC(O)-kappa-C,N)-2}}2C6H4-1',2']2 (2c). The reaction takes place in CH2Cl2 for 1a, but must be performed in glacial acetic acid for 1b and 1c. The process implies in all cases the activation of a C-H bond on a Ph ring of the phosphonium group, with concomitant formation of endo complexes. This is the expected behaviour for 1a, but for 1b and 1c reverses the exo orientation observed in other ketostabilized iminophosphoranes. The influence of the solvent in the orientation of the reaction is discussed. The dinuclear acetylacetonate complexes [{Pd(acac-O,O'){C6H4(PPh2=NCH2-kappa-C,N)-2}}2CH2] (3a), [{Pd(acac-O,O'){C6H4(PPh2=NC(O)-kappa-C,N)-2}}2C6H4-1',3'] (3b) and [{Pd(acac-O,O'){C6H4(PPh2=NC(O)-kappa-C,N)-2}}2C6H4-1',2'] (3c) have been obtained from the halide-bridging tetranuclear derivatives. The X-ray crystal structure of [3c.4CHCl3] is also reported.     

Studies on the properties of organoselenium(IV) fluorides and azides

The reaction of organoselenides and -diselenides (R2Se and (RSe)2) with XeF2 furnished the corresponding organoselenium(IV) difluorides R2SeF2 (R=Me (1), Et (2), iPr (3), Ph (4), Mes (=2,4,6-(Me)3C6H2) (5), Tipp (=2,4,6-(iPr)3C6H2) (6), 2-Me 2NCH2C6H4 (7)), and trifluorides RSeF3 (R=Me (8), iPr (9), Ph (10), Mes (11), Tipp (12), Mes* (=2,4,6-(tBu) 3C6H2) (13), 2-Me2NCH2C6H4 (14)), respectively. In addition to characterization by multinuclear NMR spectroscopy, the first molecular structure of an organoselenium(IV) difluoride as well as the molecular structures of subsequent decomposition products have been determined. The substitution of fluorine atoms with Me3SiN3 leads to the corresponding organoselenium(IV) diazides R2Se(N3)2 (R=Me (15), Et (16), iPr (17), Ph (18), Mes (19), 2-Me 2NCH2C6H4 (20)) and triazides RSe(N3)3 (R=Me (21), iPr (22), Ph (23), Mes (24), Tipp (25), Mes* (26), 2-Me2NCH2C6H4 (27)), respectively. The organoselenium azides are extremely temperature-sensitive materials and can only be handled at low temperatures.     

Syntheses and X-ray structures of potassium derivatives and a paramagnetic nickel(II) complex of a cyclodiphosph(III/V)azane monoselenide

The cyclodiphosph(III/V)azane monoselenide [(t)Bu(H)N(Se)P(micro-N(t)Bu)(2)PN(H)(t)Bu] (6, H(2)cdppSe where cdpp = cyclodiphosphazane) is obtained in quantitative yield from the comproportionation reaction of equimolar amounts of H(2)cdpp (7) and H(2)cdppSe(2) (3) in toluene at 85 degrees C. The X-ray structures of 3 and 6 reveal that both the monoselenide and the diselenide adopt a cis,endo,exo arrangement of the (t)BuNH groups. Metalation of 6 with 1 equiv of KO(t)Bu or 2 equiv of KCH(2)Ph in THF produces [(THF)K[HcdppSe]](2) (8) or [[(THF)(2)K](2)[cdppSe]](2) (9), respectively. The initial deprotonation involves the (t)BuNH group attached to the P(V) center in 6. In the dimeric structure of 8, both of the monoanionic ligands are bis-N,Se-chelated to the two K(+) cations to give a distorted K(2)N(2)Se(2) octahedron. In the centrosymmetric dimer 9, the dianionic ligands adopt two different coordination modes to the bis-solvated K(+) ions, viz., tridentate N,N',N" coordination and N,Se-chelation involving both exo- and endocyclic nitrogen atoms. The dimer is linked through K-Se interactions. The reaction of 2 equiv of 8 with NiCl(2)(PMe(3))(2) in THF produces [Ni(HcdppSe)(2)], which has a distorted tetrahedral structure and exhibits anomalous (1)H, (13)C, and (31)P NMR chemical shifts owing to the proximity of the paramagnetic Ni(II) center.     

Cluster oxalate complexes [M3(mu3-Q)(mu2-Q2)3(C2O4)3]2- and [Mo3(mu3-Q)(mu2-Q)3(C2O4)3(H2O)3]2- (M = Mo, W; Q = S, Se): mechanochemical synthesis and crystal structure

Mechanochemical reaction of cluster coordination polymers 1infinity[M3Q7Br4] (M = Mo, W; Q = S, Se) with solid K2C2O4 leads to cluster core excision with the formation of anionic complexes [M3Q7(C2O4)3]2-. Extraction of the reaction mixture with water followed by crystallization gives crystalline K2[M3Q7(C2O4)3].0.5KBr.nH2O (M = Mo, Q = S, n = 3 (1); M = Mo, Q = Se, n = 4 (2); M = W, Q = S, n = 5 (3)). Cs2[Mo3S7(C2O4)3].0.5CsCl.3.5H2O (4) and (Et4N)1.5H0.5K{[Mo3S7(C2O4)3]Br}.2H2O (5) were also prepared. Close Q...Br contacts result in the formation of ionic triples {[M3Q7(C2O4)3](2)Br}5- in 1-4 and the 1:1 adduct {[Mo3S7(C2O4)3]Br}3- in 5. Treatment of 1 or 2 with PPh(3) leads to chalcogen abstraction with the formation of [Mo3(mu3-Q)(mu2-Q)3(C2O4)3(H2O)3]2-, isolated as (Ph4P)2[Mo3(mu3-S)(mu2-S)3(C2O4)3(H2O)3].11H2O (6) and (Ph4P2[Mo3(mu3-Se)(mu2-Se)3(C2O4)3(H2O)3].8.5H2O.0.5C2H5OH (7). All compounds were characterized by X-ray structure analysis. IR, Raman, electronic, and 77Se NMR spectra are also reported. Thermal decomposition of 1-3 was studied by thermogravimetry.     

Synthesis, NMR characterisation and X-ray structures of mixed chalcogenido PNP ligands containing tellurium: crystal structures of SeiPr2PNP(H)iPr2 and [NaN(EPiPr2)2]infinity (E = Se, Te)

Reaction of HN(PiPr2)2 with one equivalent of selenium in hexane at room temperature yields the monoselenide as the P-H tautomer Se=PiPr2-N=P(H)iPr2 (2b). Deprotonation of 2b with n butyllithium in the presence of TMEDA at -78 degrees C followed by addition of tellurium produces the air-sensitive, mixed chalcogenido complex [(TMEDA)Li(SePiPr2)(TePiPr2)N] (8Li) in >97% purity after recrystallisation. Similarly, deprotonation of Te=PiPr2-N=P(H)iPr2 (2c), followed by addition of sulfur, gives the sulfur analogue [(TMEDA)Li(SPiPr2)(TePiPr2)N] (7Li) in >99% purity. The symmetrical complexes [(TMEDA)Li(SePiPr2)2N] (4Li) and [(TMEDA)Li(TePiPr2)2N] (5Li) are produced by similar methods. Compounds 2b, 4Li, 5Li, 7Li and 8Li were characterised in solution by multinuclear (1H, 31P, 77Se and 125Te) NMR spectroscopy and their solid-state structures were determined by X-ray crystallography. The X-ray crystal structures of the polymeric chains [NaN(EPiPr2)2]infinity (4Na, E = Se and 5Na, E = Te) are also reported.     

Functionalities of one-dimensional dynamic ultramicropores in nickel(II) coordination polymers

Ni(II) coordination polymers with a 4,4'-azobis(pyridine) (azpy) ligand, {[Ni2(NCX)4(azpy)4].G}n (X = S, G (guest molecule) = MeOH (1.MeOH); X = S, G = EtOH (1.EtOH); X = S, G = H2O (1.H2O); X = S, G = no guest (1); X = Se, G = MeOH (2.MeOH); X = Se, G = H2O (2.H2O); X = Se, G = no guest (2)), have been synthesized and structurally characterized with their porosity. These compounds have one-dimensional periodic ultramicropores that contain the small guest molecules, H2O, MeOH, or EtOH, whose hydroxy groups interact with the S or Se atoms of isothiocyanate or isoselenocyanate, respectively, via -S(Se)...HO- hydrogen bonds. Although the molecular dimensions of the MeOH guest are considerably larger than the window size of the ultramicropore, 1.MeOH and 2.MeOH easily release their guest molecules without decomposition of the framework to form 1 and 2 without any guest molecules. This shows that 1 and 2 have dynamic ultramicropores constructed from the interpenetrating framework. The guest desorption experiments using 1.MeOH and 1.EtOH reveal that the difference in the desorption behavior is due to van der Waals interactions that depend on the molecular shape of the guest molecule in the ultramicropores and/or an entrance blocking effect that depends on the minimum dimensions of the guest molecule for the pore windows. A marked difference in the N2 and CH4 adsorption isotherms was observed and is associated with the strength of the host-guest interaction.