[Bis(2,6-diiso-propyl-phen-yl) phosphato-κO]pentakis-(methanol-κO)manganese bis-(2,6-diiso-propyl-phen-yl) phosphate methanol tris-olvate

The title compound, [Mn(C24H34O4P)(CH3OH)5](C24H34O4P)·3CH3OH, was formed in the reaction between a hydrate of a manganese(II) salt [either Mn(NO3)2(H2O)6 or MnCl2(H2O)4] with a methanol solvate of lithium bis-(2,6-diiso-propyl-phen-yl) phosphate, {Li[OOP(O-2,6- i Pr2C6H3)2]·(CH4O)3}·CH4O, in methanol. The structure has monoclinic (Cc) symmetry at 150 K. The complex consists of an [Mn{OOP(O-2,6- i Pr2C6H3)2}(CH3OH)5]+ cation, an [OOP(O-2,6- i Pr2C6H3)2]- anion and three non-coordinating methanol mol-ecules. The anion demonstrates disorder of an isopropyl group [occupancy ratio is 0.57 (4):0.43 (4)]. The di-aryl-phosphate ligand in the cation exhibits a κ1 O terminal coordination mode. The Mn atom is in a nearly unperturbed octa-hedral environment. The [Mn{OOP(O-2,6- i Pr2C6H3)2}(CH3OH)5]+ cation exhibits one intra-molecular O-H⋯O bond, and is coordinated via two inter-molecular O-H⋯O hydrogen bonds to the [OOP(O-2,6- i Pr2C6H3)2]- anion. The cations, anions and non-coordinating methanol mol-ecules are linked into infinite chains along the c-axis direction via 0-H⋯O hydrogen bonding. The complex is of inter-est as a possible inhibitor for the thermal decomposition of polydi-methyl-siloxane. The crystal studied was refined as an inversion twin with a domain ratio of 0.47 (3):0.53 (3).

Synthesis, magnetic behaviour, and X-ray structures of dinuclear copper complexes with multiple bridges. Efficient and selective catalysts for polymerization of 2,6-dimethylphenol

The use of a potentially tridentate mono-anionic bridging ligand, 1,3-bis(3,5-dimethylpyrazol-1-yl)-propan-2-ol (bdmpp-H), in assembling new dimeric copper complexes with interesting magnetic properties has been investigated. The reaction of copper hydroxide or copper acetate with phenyl phosphinic acid or diphenyl phosphinic acid in the presence of bdmpp-H produces the dinuclear complexes [Cu(bdmpp)(ppi)]2 (1) and [Cu(bdmpp)(dppi-H)]2(dppi)2 (2) (ppi-H = phenylphosphinic acid: dppi-H = diphenylphosphinic acid), respectively. The products have been characterized with the help of analytical, thermal, and spectroscopic (IR, UV-vis, and EPR) techniques. Single crystal X-ray diffraction studies of 1 and 2 reveal that the two bdmpp ligands hold together the dimeric copper unit in each complex through mu-O alkoxide and the pyrazolyl nitrogen ligating centers. Two phenyl phosphinate ligands additionally bridge the dicopper core in 1 to result in octahedral coordination geometry around each metal ion. The diphenyl phosphinic acid acts as a terminal ligand in 2, and thus completes a square pyramidal geometry around each copper ion. Both complexes show a very short Cu...Cu separation (3.001 and 3.065 angstroms for 1 and 2, respectively). The investigation of the magnetic properties reveals the efficiency of the double alkoxide bridge between the two paramagnetic copper ions to mediate strong antiferromagnetic interactions [J/k(B) = -620(5) K (-431(4) cm(-1)) and -685(5) K (-476(4) cm(-1)) for 1 and 2, respectively]. Compounds 1 and 2, along with a few other copper phosphate complexes, were tested as catalysts for the oxidative polymerization of 2,6-dimethylphenol; 1 and 2 were found to be efficient catalysts with an increased selectivity for the formation of the polyphenylene ether. However a related mononuclear octahedral copper complex [Cu(imz)4(dtbp)2] (dtbp-H = di-tert-butylphosphate) was found to be more efficient.

A Stabilized β-Oxaphosphoniumbetaine: An Elusive Zwitterion

A beta-oxaphosphoniumbetaine stabilized by two tert-butyl groups at the phosphonium part of the betaine and two trifluoromethyl groups at the carbon adjoined to the oxa part of the betaine was isolated and structurally characterized. Additional stabilization results from the solvation of the betaine by a parent phosphonium salt, as in 4, or by protonation with methanol, as in 10. According to X-ray analysis, the betaine exhibits a sterically strained "gauche" conformeric form, with torsion angles in the P-C-C-O moiety of 32.2 degrees for 4 and 28.1 degrees for 10. The P...O separations of 3.121 A for 4 and 3.086 A for 10 are just under the sum of the O and P van der Waals radii (3.32 A). The fast H/D exchange of alpha hydrogen atoms to the phosphonium center was observed in the solution of 10 in deuterium oxide and MeOH-d4. The beta-oxaphosphoniumbetaine has long been suspected as an intermediate in the Wittig reaction, but this is the first time a stabilized derivative has been isolated.

Non-Interpenetrating Transition Metal Diorganophosphate 2-Dimensional Rectangular Grids from Their 1-Dimensional Wires: Structural Transformations under Mild Conditions

The manganese, cobalt, and cadmium complexes [M(dtbp)2]n (M = Mn (1) and Co 2) and [Cd(dtbp)2(H2O)]n (3) (dtbp = di-tert-butyl phosphate), which exist as one-dimensional molecular wires, transform to non-interpenetrating rectangular grids [M(dtbp)2(bpy)2.2H2O]n (M = Mn (4), Co (5), and Cd (6)) by the addition of 4,4-bipyridine (bpy) at room temperature. Products 4-6 have also been prepared by a room-temperature reaction or by solvothermal synthesis in methanol through a direct reaction between the metal acetate, di-tert-butyl phosphate, and 4,4'-bipyridine (bpy) in a 1:2:2 molar ratio. Single-crystal X-ray structure determination of 4-6 shows that these compounds are composed of octahedral transition metal ions woven into a two-dimensional grid structure with the help of bpy spacer ligands. The axial coordination sites at the metal are occupied by bulky unidentate dtbp ligands, which prevent any interpenetration of the individual grids. The change of reaction conditions from solvothermal to hydrothermal, for the attempted synthesis of a magnesium grid structure, however leads to the isolation of an organic phosphate [(H2bpy)(H2PO4)2] (7) and an inorganic phosphate [Mg(HPO4)(OH2)3] (8). Compound 7 can also be prepared quantitatively from a direct reaction between bpy and H3PO4. The new organic phosphate 7 is a unique example of a phosphate material with alternating layers of [H2bpy]2+ cations and [H2PO4]- anions that are held together by hydrogen bonds. Solid-state thermal decomposition of 4-6 produced the respective metaphosphate materials [M(PO3)2] (M = Mn (9), Co (10), and Cd (11)). All new metal-organic phosphates have been characterized by elemental analysis, thermal analysis (TGA, DTA, DSC), and IR and NMR spectroscopy. The metaphosphate ceramic materials were characterized by IR spectral and powder X-ray diffraction studies.

Cobalt and Manganese Nets via Their Wires: Facile Transformation in Metal−Diorganophosphates

The manganese and cobalt complexes [M(dtbp)2]n (M=Mn, Co; dtbp=di-tert-butyl phosphate), which exist as one-dimensional molecular wires, transform to [M(dtbp)2(bpy)2.2H2O]n by the addition of 4,4-bipyridine (bpy) at room temperature; the latter compounds form noninterpenetrating rectangular grid structures.

Monomeric, Tetrameric, and Polymeric Copper Di-tert-butyl Phosphate Complexes Containing Pyridine Ancillary Ligands,

The reaction of di-tert-butyl phosphate (((t)BuO)(2)P(O)(OH), dtbp-H) with copper acetate in the presence of pyridine (py) and 2,4,6-trimethylpyridine (collidine) has been investigated. Copper acetate reacts with dtbp-H in a reaction medium containing pyridine, DMSO, THF, and CH(3)OH to yield a one-dimensional polymeric complex [Cu(dtbp)(2)(py)(2)(mu-OH(2))](n) (1) as blue hollow crystalline tubes. The copper atoms in 1 are octahedral and are surrounded by two terminal phosphate ligands, two pyridine molecules, and two bridging water molecules. The mu-OH(2) ligands that are present along the elongated Jahn-Teller axis are responsible for the formation of the one-dimensional polymeric structure. Recrystallization of 1 in a DMSO/THF/CH(3)OH mixture results in the reorganization of the polymer and its conversion to a more stable tetranuclear copper cluster [Cu(4)(mu(3)-OH)(2)(dtbp)(6)(py)(2)] (2) in about 60% yield. The molecular structure of 2 is made up of a tetranuclear core [Cu(4)(mu(3)-OH)(2)] which is surrounded by six bidentate bridging dtbp ligands. While two of the copper atoms are pentacoordinate with a tbp geometry, the other two copper atoms exhibit a pseudooctahedral geometry with five normal Cu-O bonds and an elongated Cu-O linkage. The pentacoordinate copper centers bear an axial pyridine ligand. The short Cu.Cu nonbonded distances in the tetranuclear core of 2 lead to magnetic ordering at low temperature with an antiferromagnetic coupling at approximately 20 K (J(P) = -44 cm(-1), J(c) = -66 cm(-1), g = 2.25, and rho = 0.8%). When the reaction between di-tert-butyl phosphate (dtbp-H) and copper acetate was carried out in the presence of collidine, large dark-blue crystals of monomeric copper complex [Cu(dtbp)(2)(collidine)(2)] (3) formed as the only product. A single-crystal X-ray diffraction study of 3 reveals a slightly distorted square-planar geometry around the copper atom. Thermogravimetric analysis of 1-3 revealed a facile decomposition of the coordinated ligands and dtbp to produce a copper phosphate material around 500 degrees C. An independent solid-state thermolysis of all the three complexes in bulk at 500-510 degrees C for 2 days produced copper pyrophosphate Cu(2)P(2)O(7) along with small quantities of Cu(PO(3))(2) as revealed by DR-UV spectroscopic and PXRD studies.

Reactivity studies, structural characterization, and thermolysis of cubic titanosiloxanes: precursors to titanosilicate materials which catalyze olefin epoxidation

The cubic titanosiloxane [RSiO(3)Ti(OPr(i))](4) (R = 2,6-Pr(2)(i)C(6)H(3)NSiMe(3)) (1) is found to be relatively inert in its attempted reactions with alcohols and other acidic hydrogen containing compounds. The reaction of 1 with silanol (Bu(t)O)(3)SiOH however proceeds over a period of approximately 3 months to result in the hydrolysis of (Bu(t)O)(3)SiOH and yield the transesterification product [RSiO(3)Ti(OBu(t))](4) (2) rather than the expected [RSiO(3)Ti(OSi(OBu(t))(3))](4). Products 1 and 2 have been characterized by elemental analysis, thermal analysis, and spectroscopic techniques (IR, EI-MS, and NMR). The solid-state structures of both 1 and 2 have been determined by single-crystal X-ray diffraction studies. Compounds 1 and 2 are isomorphous and crystallize in a cubic space group with a central cubic Ti(4)Si(4)O(12) core. Solid state thermolysis of 1 was carried at 450, 600, 800, 900, 1000, and 1200 degrees C in air, and the resulting titanosilicate materials 1a-f were characterized by spectroscopic (IR and DR UV), powder XRD, and electron microscopic methods. While, the presence of Ti-O-Si linkages appears to be dominant in the samples prepared at lower temperatures (450-800 degrees C), phase separation of anatase and rutile forms of TiO(2) occurs at temperatures above 900 degrees C as revealed by IR spectral and PXRD studies. The presence of octahedral titanium centers was observed by DR UV spectroscopy for the samples heated at higher temperatures. The use of new titanosilicate materials as catalysts for olefin epoxidation has been investigated. The titanosilicate materials produced at temperatures below 800 degrees C with a large number of Ti-O-Si linkages (or tetrahedral titanium centers) were found to be more active catalysts compared to the materials produced above 900 degrees C. The observed conversion in the epoxidation reactions was found to be somewhat low although the selectivity of the epoxide formation over the other possible oxidized products was found to be very good.

O–H Bond elongation in co-ordinated water through intramolecular PO⋯H–O bonding. ‘Snap-shots’ in phosphate ester hydrolysis

Molecular structure of [Cu(dtbp)2(phen)(OH2)] (dtbp-H = di-tert-butylphosphate, phen = 1,10-phenanthroline), determined at 293, 203 and 93 K, provides useful snap-shots of O-H bond activation of a metal-bound water, which is aided by an intramolecular P=O...H-O hydrogen bonding interaction.

Di-tert-butyl phosphate as synthon for metal phosphate materials via single-source coordination polymers [M(dtbp)(2)](n) (M = Mn, Cu) and [Cd(dtbp)(2)(H2O)](n) (dtbp-H = (tBuO)(2)P(O)OH)

Reaction of M(OAc)(2).xH(2)O (M = Mn, Cu, or Cd) with di-tert-butyl phosphate (dtbp-H) in a 1:2 molar ratio in methanol followed by slow crystallization of the resultant solid in MeOH/THF medium results in the formation of three new polymeric metal phosphates [M(dtbp)(2)](n)() [M = Mn, 1 (beige); M = Cu, 2 (blue)] and [Cd(dtbp)(2)(H(2)O)](n)(), 3 (colorless)] in good yields. The formation of [Mn(dtbp)(2)](n) (1) proceeds via tetrameric manganese phosphate [Mn(4)(O)(dtbp)(6)] (4), which has been isolated in an analytically pure form. Perfectly air- and moisture-stable compounds 1-4 were characterized with the aid of analytical, thermoanalytical, and spectroscopic techniques. The molecular structures of 1-3 were further established by single-crystal X-ray diffraction studies. Crystal data for 1: C(32)H(72)Mn(2)O(16)P(4), monoclinic, P2(1)/c, a = 19.957(4) A, b = 13.419(1) A, c = 18.083(2) A, beta = 91.25(2) degrees, Z = 4. Crystal data for 2: C(16)H(36)CuO(8)P(2), orthorhombic, Pccn, a = 23.777(2) A, b = 10.074(1) A, c = 10.090(1) A, Z = 4. Crystal data for 3: C(48)H(114)Cd(3)O(27)P(6), triclinic, P1, a = 12.689(3) A, b = 14.364(3) A, c = 22.491(5) A, alpha = 84.54(3) degrees, beta = 79.43(3) degrees, gamma = 70.03(3) degrees, Z = 2. The diffraction studies reveal three different structural forms for the three compounds investigated, each possessing a one-dimensional coordination polymeric structure. While alternating triple and single dtbp bridges are found between the adjacent Mn(2+) ions in 1, uniform double dtbp bridges across the adjacent Cu(2+) ions are present in 2. The cadmium ions in the structure of 3 are pentacoordinated. Thermal analysis (TGA and DSC) indicates that compounds 1-3 convert to the corresponding crystalline metaphosphate materials M(PO(3))(2), in each case at temperatures below 500 degrees C. Similarly, the thermal decomposition of 4 results in the formation of Mn(PO(3))(3) and Mn(2)P(2)O(7). The final materials obtained by independent thermal decomposition of bulk samples have been characterized using IR spectroscopic, powder diffraction, and N(2) adsorption studies.