Syntheses, Spectroscopy, Structures, and Reactivity of Neutral Cubic Group 13 Molecular Phosphonates

Facile room-temperature synthesis of layered transition metal phosphonates via hitherto unknown alkali metal tert-butyl phosphonates

A facile room-temperature synthetic method is presented to produce alkali metal salts of tert-butyl phosphonic acid. The reaction between equimolar amounts of alkali metal carbonates and tert-butyl phosphonic acid in methanol results in the formation of [(tBuPO3H)Li(H2O)3·(H2O)] (1), [(tBuPO3)Na2(H2O)4]n (2), and [(tBuPO3H)K(H2O)]n (3). Solid-state structures of these compounds have been confirmed by single-crystal X-ray diffraction studies and further validated using numerous spectroscopic and analytical techniques. Compounds 1-3 are polymeric solids that are predominantly made up of a 1-D polymeric metal phosphonate chain. This synthetic approach leads to the formation of network structures/polymers in the solid state that otherwise are absent in solution due to the ionic nature of the interaction between the alkali metal ions and phosphonate anions. Apart from the multidentate nature of the phosphonate ligands, additional hydrogen bonding interactions involving water molecules, free P-OH groups, and PO moieties allow these chains to be propagated into 2-D sheets. We have further utilized the completely metalated sodium phosphonate 2 to synthesize layered metal phosphonates [(tBuPO3)Ca(H2O)]n (4), [(tBuPO3)Mn(H2O)]n (5) and [(tBuPO3)Co(H2O)]n (6) via a simple metathesis reaction.

Synthesis of Organosilyl-Functionalized Cage-Type Germanoxanes Containing Fluoride Ions

Eight corners of a double-four ring cage-type germanoxane, containing a fluoride ion, were successfully silylated by the combination of chlorosilanes and silazanes. Three different silyl groups, trimethylsilyl, dimethylsilyl, and dimethylvinylsilyl, were attached on the corners of germanoxane cage. The solubility and reactivity of the cage modified with dimethylvinylsilyl groups were significantly increased, allowing for further reaction. Hydrosilylation reaction between dimethylvinylsilylated cage geramanoxanes and dimethylsilylated cage siloxanes afforded porous solids. Functionalization of the corners of germanoxanes with silyl groups should provide valuable building blocks in various functional materials.

New molecular heptanuclear cobalt phosphonates: synthesis, structures and magnetic properties

Synthesis, structures and magnetic properties (strong anisotropy, ferromagnetic and antiferromagnetic interactions) of novel {Co₇} homoleptic molecular cobalt phosphonates with a similar structure motif are described.

Monoorganoantimony(v) phosphonates and phosphoselininates

Molecular oxo-hydroxo clusters have been synthesized by reactions of arylstibonic acids with organophosphonic acid and phenylseleninic acid. Single crystal X-ray structural elucidation revealed the formation of [(p-i-PrC6H4Sb)4(OH)4(t-BuPO3)6] (1), [(p-t-BuC6H4Sb)4(O)2(PhPO3)4(PhPO3H)4] (2), [(p-i-PrC6H4Sb)4(O)3(OH)(PhSeO2)2(t-BuPO3)4(t-BuPO3H2)2] (3), [(p-MeC6H4Sb)4(O)3(OH)(PhSeO2)2(t-BuPO3)4(t-BuPO3H2)2] (4) and [(p-t-BuC6H4Sb)2(O) (PhSeO2)2(t-BuPO3H)4] (5) respectively. Mass spectral studies reveal that the clusters maintain their structural integrity in solution as well. Solution NMR studies ((1)H, (31)P and (77)Se) show spectral patterns which correlate well with the observed solid state structures of 1-5.

Alkylzinc diorganophosphates: synthesis, structural diversity and unique ability to incorporate zincoxane units

New tetrameric alkylzinc organophosphates of a drum-like structure and novel aggregates based on alkylzinc organophosphates with incorporated zincoxane units were synthesized and structurally characterized.

Increasing the Brønsted acidity of Ph2PO2H by the Lewis acid B(C6F5)3. Formation of an eight-membered boraphosphinate ring [Ph2POB(C6F5)2O]2

The strong acid (C₆F₅)₃BOPPh₂OH, was prepared in situ by the reaction of the rather weak Brønsted acid Ph₂PO₂H with the strong Lewis acid B(C₆F₅)₃.

Synthetic strategies to achieve further-functionalised monoaryl phosphate primary building units: crystal structures and solid-state aggregation behavior

The synthesis of a new class of functionalized organophosphates, potential building units in materials and zeolite chemistry, has been reported.

Synthesis of heteroboroxines with MB₂O₃ core (M = Sb, Bi, Sn)--an influence of the substitution of parent boronic acids

The synthesis and structure of stiba-, stanna- and bismaheteroboroxines of a general formula L(E)M[(OBR)2O] supported by a N,C,N-chelating ligand L [where L = C6H3-2,6-(CH2NMe2)2, M, E = Sb, lone pair or Sn, Ph or Bi, lone pair] is reported. The target compounds are prepared by straightforward one-step reactions between oxides (LMO)2 (M = Sb or Bi) or organotin(iv) carbonate L(Ph)Sn(CO3) with four or two molar equivalents of corresponding organoboronic acid. All compounds were characterized with the help of elemental analysis, multinuclear NMR spectroscopy and on several occasions the molecular structure was determined using single-crystal X-ray diffraction analysis. The influence of both the substitution of the parent organoboronic acid and the central atom used on the feasibility of the condensation reaction was addressed. Furthermore, several heteroboroxines containing nitrogen donor functionality (i.e. NH2, NMe2, CN or 4-pyridyl) included in the boronic acid residue were synthesized and characterized with the aim to prepare boroxine-based covalent frameworks (through intermolecular N→B interactions) containing metal atoms in their structures. Although no such intermolecular bonding was detected in solution of these compounds, it was shown that the organotin(iv) heteroboroxine substituted by 4-pyridyl group forms an infinite polymeric chains via N→B interactions in the solid state. This polymer collapsed back to monomeric units upon dissolution.

Seeking tetrameric transition metal phosphonate with a D4R core and organising it into a 3-D supramolecular assembly

The first cubic zinc phosphonate [tBuPO(3)Zn(2-apy)](4) (1) whose core resembles the D4R SBU of zeolites, has been synthesised from a reaction between zinc acetate, tert-butylphosphonic acid and 2-aminopyridine at room temperature; the X-ray structure determination reveals that the molecules of , which crystallise in the tetragonal I4(1)/a space group with crystallographically imposed 4 symmetry, form a 3-D supramolecular assembly aided by N-H...O hydrogen bonding.

Metal cages using a bulky phosphonate as a ligand

The synthesis, structure, magnetic and electronic properties of soluble transition metal phosphonate cages utilizing tritylphosphonic acid (TPA) as ligand are reported.

Preparation and Structural Characterization of Three Types of Homo- and Heterotrinuclear Boron Complexes: Salen{[B−O−B][O2BOH]}, Salen{[B−O−B][O2BPh]}, and Salen{[B−O−B][O2P(O)Ph]}

Three types of homo- and heterotrinuclear boron complexes have been obtained in moderate to good yields from reactions of salen-type ligands with boric acid and combinations of boric acid with phenylboronic and phenylphosphonic acid. The products are air-stable and have relatively high melting points (>290 degrees C) but are poorly soluble or insoluble in common organic solvents. They have been characterized as far as possible by elemental analysis, mass spectrometry, IR, (1)H, (11)B, and (31)P NMR spectroscopy, and X-ray crystallography. Furthermore, theoretical calculations have been performed for representative examples to permit a complete comparison of the different structure types. A detailed analysis of the molecular structures showed that the complexes are constructed around a central B(3)O(3) or B(2)PO(3) ring. The salen ligands are attached to two boron atoms of these rings, which have therefore tetrahedral coordination geometries. The complexes contain seven- and eight-membered heterocycles of the B(2)C(n)ON(2) (n = 2, 3) type with chair or twisted-chair and boat-chair or chair-chair conformations, respectively. In the homotrinuclear complexes one of the three boron atoms is three-coordinate and can therefore still act as Lewis acid, thus making these products interesting for catalytic applications, e.g. in asymmetric synthesis. Depending on the substitutents attached to the boron atoms, these complexes show a relationship with either trimetaboric acid, boroxine, or the tetraborate dianion found in Borax.

Synthesis and characterization of a novel cyclic aluminophosphinate: structure and solid-state NMR study

We present the structure and a multinuclear solid-state NMR study of a new cyclic aluminophosphinate. The crystallographic structure of [Al(2)(HC(6)H(5)PO(2))(2)(C(4)H(9)OH)(8)]Cl(4) (compound 1) was obtained at low temperature (a = 11.830(7) A, b = 14.216(6) A, c = 17.790(6) A, beta = 91.25(4) degrees, monoclinic, P21/c, Z = 2). (13)C IRCP (inversion recovery cross polarization) and NQS (non quaternary suppression) NMR experiments allowed the complete assignment of the quaternary carbon atom of the phenyl ring and the precise determination of the isotropic /(1)J(P-C)/ coupling constant. (31)P CP MAS dynamics was carefully studied by varying the contact time. Dipolar oscillations even at slow MAS were observed. Up to 11 kHz, these oscillations were more pronounced, and the P-H distance was easily extracted. (27)Al NMR quadrupolar parameters for 1 were obtained with very good accuracy, and unusual satellite transition splitting was observed. Furthermore, the isotropic lines of the inner and outer transitions were clearly observable, leading to the unambiguous determination of the quadrupolar parameters.

Ligand-tetrahydrofuran coupling in chelated aluminum phosphinates

When the reagents LAlMe (L = N,N'-(alkylene or arylene)bis(3,5-di-tert-butyl)salicylideneimine (alkylene = ethylene (Salen(tBu))(1), propylene (Salpen(tBu))(2), and butylene (Salben(tBu)) (3); arylene = phenylene (Salophen(tBu) (4), 3,4-dimethylphenylene (Salomphen(tBu) (5)) are combined with Ph(H)P(O)OH in tetrahydrofuran (thf) the unique aluminophosphinate compounds, [L(tBu)Al[O(2)P(H)Ph]](n) with L, n = Salen,(infinity)(6), Salpen, 2 (7), Salben, 2 (8), Salophen, (infinity)(9) and Salomphen, (infinity)(10) are produced. The yields for the latter two reactions are low, and it was subsequently found that the unique thf-coupled compounds appear in the thf filtrates of the original reaction mixture. These compounds are, [L-thf(tBu)Al[O(2)P(H)Ph]](2), L = Salophen (13) and Salomphen (14). The thf connects through an alpha-carbon to only one of the two possible imine carbons of the ligand. While trying to determine how this coupling proceeds, the six-coordinate, solution-state species LAlMe(thf) (L = Salophen (11) and Salomphen (12) were discovered and implicated as intermediates. All of the compounds are characterized by melting point, NMR, IR, and X-ray analyses for 5-8, 13, and 14. A possible mechanism for the thf coupling event is presented.

Synthesis and Structural Characterization of Functionalized Dimeric Aluminophosphonates and a Monomeric Gallophosphonate Anion

Reaction of t-BuP(O)(OSiMe(3))(OH) with Me(3)Al leads to the formation of [Me(2)Al(mu-O)(2)P(OSiMe(3))(t-Bu)](2) (1) whereas Me(2)AlCl reacts with Ph(2)P(O)(OH) to yield [(Cl)(Me)Al(mu-O)(2)PPh(2)](2) (2). These compounds represent the first examples of functionalized dimeric four-ring type aluminophosphonate systems. The double four-ring type gallophosphonate, namely, [t-BuPO(3)GaMe](4), reacts with n-Bu(4)NHF(2) under ambient conditions, resulting in the formation of a monomeric gallophosphonate [n-Bu(4)N][MeGa[t-BuPO(2)(OH)](3)] (3). These derivatives have been adequately characterized using various spectroscopic techniques and X-ray diffraction studies.

Di-tert-butyl phosphate complexes of cobalt(II) and zinc(II) as precursors for ceramic M(PO3)2 and M2P2O7 materials: synthesis, spectral characterization, structural studies, and role of auxiliary ligands

Reaction of the metal acetates M(OAc)2xH2O with di-tert-butyl phosphate (dtbp-H) (3) in a 4:6 molar ratio in methanol or tetrahydrofuran followed by slow evaporation of the solvent results in the formation of metal phosphate clusters [M4(mu 4-O)(dtbp)6] (M = Co (4, blue); Zn (5, colorless)) in nearly quantitative yields. The same reaction, when carried out in the presence of a donor auxiliary ligand such as imidazole (imz) and ethylenediamine (en), results in the formation of octahedral complexes [M(dtbp)2(imz)4] (M = Co (6); Ni (7); Zn (8)) and [Co(dtbp)2-(en)2] (9). The tetrameric clusters 4 and 5 could also be converted into mononuclear 6 and 8; respectively, by treating them with a large excess of imidazole. The use of slightly bulkier auxiliary ligand 3,5-dimethylpyrazole (3,5-dmp) in the reaction between cobalt acetate and 3 results in the isolation of mononuclear tetrahedral complex [Co(dtbp)2(3,5-dmp)2] (10) in nearly quantitative yields. Perfectly air- and moisture-stable samples of 4-10 were characterized with the aid of analytical, thermoanalytical, and spectroscopic techniques. The molecular structures of the monomeric pale-pink compound 6, colorless 8, and deep-blue 10 were further established by single-crystal X-ray diffraction studies. Crystal data for 6: C28H52CoN8O8P2, a = 8.525(1) A, b = 9.331(3) A, c = 12.697(2) A, alpha = 86.40(2) degrees, beta = 88.12(3) degrees, gamma = 67.12(2) degrees, triclinic, P1, Z = 1. Crystal data for 8: C28H52N8O8P2Zn, a = 8.488(1) A, b = 9.333(1) A, c = 12.723(2) A, alpha = 86.55(1) degrees, beta = 88.04(1) degrees, gamma = 67.42(1) degrees, triclinic, P1, Z = 1. Crystal data for 10: C26H52CoN4O8P2, a = b = 18.114(1) A, c = 10.862(1) A, tetragonal, P4(1), Z = 4. The Co2+ ion in 6 is octahedrally coordinated by four imidazole nitrogens which occupy the equatorial positions and oxygens of two phosphate anions on the axial coordination sites. The zinc derivative 8 is isostructural to the cobalt derivative 6. The crystal structure of 10 reveals that the central cobalt atom is tetrahedrally coordinated by two phosphate and two 3,5-dmp ligands. In all structurally characterized monomeric compounds (6, 8, and 10), the dtbp ligand acts as a monodentate, terminal ligand with free P=O phosphoryl groups. Thermal studies indicate that heating the samples at 171 (for 4) or 93 degrees C (for 5) leads to the loss of twelve equivalents of isobutene gas yielding carbon-free [M4(mu 4-O)(O2P(OH)2)6], which undergoes further condensation by water elimination to yield a material of the composition Co4O19P6. This sample of 4 when heated above 500 degrees C contains the crystalline metaphosphate Co(PO3)2 along with amorphous pyrophosphate M2P2O7 in a 2:1 ratio. Similar heat treatment on samples 6-8 results in the exclusive formation of the respective metaphosphates Co(PO3)2, Ni(PO3)2, and Zn(PO3)2; the tetrahedral derivative 10 also cleanly converts into Co(PO3)2 on heating above 600 degrees C.

Application of n-Bu4NHF2 as a fluorinating agent for the preparation of fluoroanions: synthesis and crystal structure of the anions [t-BuPO3AlF2]2(2-), [PhPO3AlF2]2(2-), and [(O-i-Pr)3Ti(mu-F)2(mu-O-i-Pr)Ti(O-i-Pr)3]-

The first phosphonate anions of aluminum-containing fluorine and an anionic bridged fluoroalkoxy derivative of titanium have been realized using n-Bu4NHF2 as a fluorinating agent in organometallic synthesis. Reactions of [RPO3AlMe]4 [R = Ph (1), t-Bu] with n-Bu4NHF2 yield organic-soluble compounds of the type [n-Bu4N]2[RPO3AlF2]2 [R = Ph (2), t-Bu (3)], whereas the reaction of Ti(O-i-Pr)4 with n-Bu4NHF2 results in the formation of [n-Bu4N][O-i-Pr)3Ti(mu-F)2(mu-O-i-Pr)Ti(O-i-Pr)3] (4). These compounds have been obtained in high yields and have been adequately characterized through spectroscopic techniques and X-ray diffraction studies.

Synthesis and Characterization of Dimeric, Trimeric, and Tetrameric Gallophosphonates and Gallophosphates

THF/toluene solutions of phosphonic or phosphoric acids were reacted with (t)Bu(3)Ga at low temperature to yield the cyclic dimers [(t)Bu(2)GaO(2)P(OH)R](2) (R = Ph, Me, (t)Bu, H, OH; 1-5). Poor crystallinity and variable thermal stabilities of 1-5 necessitated derivatization with Me(3)SiNMe(2) to yield [(t)Bu(2)GaO(2)P(OSiMe(3))R](2) (R = Ph, Me, (t)Bu, H, OSiMe(3); 6-10), which were more amenable to purification and characterization. In solution, trans isomers were predominant for 6 and 7 at ambient temperature, whereas the cis isomer of 8 was predominant. NMR spectroscopy demonstrated cis-trans interconversion for 6-8 and crossover experiments showed interconversion to occur by, or be accompanied with, an intermolecular exchange process. Thermolysis of 3 in refluxing toluene yielded the cluster [((t)BuGa)(2)((t)Bu(2)Ga)(O(3)P(t)Bu)(2){O(2)P(OH)(t)Bu}] (11), which was converted to [((t)BuGa)(2)((t)Bu(2)Ga)(O(3)P(t)Bu)(2){O(2)P(OSiMe(3))(t)Bu}] (12) with Me(3)SiNMe(2). Thermolysis of 1-3 in refluxing diglyme, or solid-state pyrolysis at 250 degrees C in vacuo, yielded [(t)BuGaO(3)PR](4) (R = Ph, (t)Bu, Me; 13-15). The gallophosphate [(t)BuGaO(3)P(OSiMe(3))](4) (16) was similarly obtained by reaction of (t)Bu(3)Ga with H(3)PO(4) in refluxing diglyme, followed by trimethylsilylation with Me(3)SiNMe(2). Compounds 13-16 possess cuboidal Ga(4)P(4)O(12) cores analogous to double-four-ring secondary building units in the gallophosphates cloverite, gallophosphate-A, and ULM-5. The thermal, hydrolytic, and oxidative stabilities of 13-16 are discussed, as are observed intermolecular exchange processes. In addition to characterization of 1-16 by multinuclear ((1)H, (13)C, (31)P) NMR spectroscopy, infrared spectroscopy, mass spectrometry, and elemental analysis, molecular structures for compounds 6, 8, 10, 12, 14, 15, and 16 were determined by X-ray crystallography.