Anne F. Richards

A neutral, monomeric germanium(I) radical

Stoichiometric reduction of the bulky β-diketiminato germanium(II) chloride complex [((But)Nacnac)GeCl] ((But)Nacnac = [{N(Dip)C(Bu(t))}(2)CH](-), Dip = C(6)H(3)Pr(i)(2)-2,6) with either sodium naphthalenide or the magnesium(I) dimer [{((Mes)Nacnac)Mg}(2)] ((Mes)Nacnac = [(MesNCMe)(2)CH](-), Mes = mesityl) afforded the radical complex [((But)Nacnac)Ge:](•) in moderate yields. X-ray crystallographic, EPR/ENDOR spectroscopic, computational, and reactivity studies revealed this to be the first authenticated monomeric, neutral germanium(I) radical.

Convenient synthesis of aluminum and gallium phosphonate cages.

The reactions of AlCl 3.6H 2O and GaCl 3 with 2-pyridylphosphonic acid (2PypoH 2) and 4-pyridylphosphonic acid (4PypoH 2) afford cyclic aluminum and gallium phosphonate structures of [(2PypoH) 4Al 4(OH 2) 12]Cl 8.6H 2O ( 1), [(4PypoH) 4Al 4(OH 2) 12]Cl 8.11H 2O ( 2), [(2PypoH) 4Al 4(OH 2) 12](NO 3) 8.7H 2O ( 3), [(2PypoH) 2(2Pypo) 4Ga 8Cl 12(OH 2) 4(thf) 2](GaCl 4) 2..8thf ( 4), and [(2PypoH) 2(2Pypo) 4Ga 8Cl 12(OH 2) 4(thf) 2](NO 3) 2.9thf ( 5). Structures 1- 3 feature four aluminum atoms bridged by oxygen atoms from the phosphonate moiety and show structural resemblance to the secondary building units found in zeolites and aluminum phosphates. The gallium complexes, 4 and 5, have eight gallium atoms bridged by phosphonate moieties with two GaCl 4 (-) counterions present in 4 and nitrate ions in 5. The cage structures 1- 3 are interlinked by strong hydrogen bonds, forming polymeric chains that, for aluminum, are thermally robust. Exchange of the phosphonic acid for the more flexible 4PyCH 2PO 3H 2 afforded a coordination polymer with a 1:1 Ga:P ratio, {[(4PyCH 2PO 3H)Ga(OH 2) 3](NO 3) 2.0.5H 2O} x ( 6). Complexes 1- 6 were characterized by single-crystal X-ray diffraction, NMR, and mass spectrometry and studied by TGA.

An Unprecedented Fe36 Phosphonate Cage

The reaction of 2-pyridylphosphonic acid (LH(2)) with iron(II) perchlorate and iron(III) nitrate afforded an interconnected, double-layered, cationic iron cage, [{Fe(36)L(44)(H(2)O)(48)}](20+) (1a), the largest interconnected, polynuclear ferric cage reported to date. Magnetic studies on 1a revealed antiferromagnetic coupling between the spins on adjacent Fe(III) ions.

The interaction of phosphavinyl Grignard reagents with group 15 halides: synthesis and structural characterisation of novel heterocyclic and heterocage compounds

The reactions of a phosphavinyl Grignard reagent, [CyPC(But)MgCl(OEt2)], Cy = cyclohexyl, with a variety of group 15 halide compounds in a number of stoichiometries have been investigated. When the Grignard reagent is reacted with Ph2PCl or CyPCl2, Cy = cyclohexyl, in a 1∶1 and 2∶1 stoichiometry respectively, the 1,3-diphosphapropene, Ph2PC(But)PCy, and triphosphabicyclo[2.1.0]pentane compound, CyP{C2(But)2P2Cy2}, are formed. The 2∶1 and 3∶1 reactions of the Grignard reagent with either PCl3 or AsCl3 lead to the strained triphospha- and arsadiphosphabicyclo[1.1.1]pentanes, ButC{μ-P(Cy)}2{μ-ECl}CBut, E = P or As in moderate yield. The related 1∶1 reaction of the Grignard reagent with PCl3 affords two products, a phosphino-substituted phosphorus ylide, Cl2PC(But)P(Cy)(Cl)2, and a tetraphosphabicyclo[2.1.1]hexane, ButC{μ-P(Cl)P(Cy)}{μ-P(Cy)}{μ-P(Cl)}CBut, the mechanism of formation of which is discussed. An analogous 1∶1 reaction of the Grignard reagent with SbCl3 led to an unusual heterocyclic compound, (Cl2Sb)(But)CSb(Cl)C(But)P(Cl)(Cy)P(Cy), which quantitatively decomposes in solution to yield the known 1,2-dihydro-1,2-diphosphete, P2(Cy)2C2(But)2. All prepared compounds have been crystallographically characterised.

The synthesis and structural characterisation of the first phosphavinyl–Group 13 complexes

The bisphosphavinyl indium complex, [CyIn{C( t Bu)PCy} 2 ], has been prepared from the reaction of two equivalents of [CyPC( t Bu)MgCl(OEt 2 )] with CyInBr 2 . Its crystal structure shows it to be monomeric with a trigonal planar indium centre. The reactions of [CyPC( t Bu)MgCl(OEt 2 )] with MX 3 , M=Al, Ga or In, X=Cl or Br, leads to facile phosphavinyl coupling reactions and the formation of the diphosphametallobicyclo[1.1.1]pentane complexes, [M{C 2 ( t Bu) 2 P 2 Cy 2 }{C( t Bu)PCy}], which contain terminal phosphavinyl ligands.

Reactions of a phosphavinyl Grignard reagent with main group mono-halide compounds

Abstract The reactions of a phosphavinyl Grignard reagent, [CyPC(But)MgCl(OEt2)] Cy=cyclohexyl, with a variety of main group 13, 14 and 16 mono-halide compounds have been investigated. When the Grignard reagent is reacted with bromocatecholborane the terminal phosphavinyl complex, [(C6H4O2)B{C(But)PCy}], is formed. Related terminal phosphavinyl tin and gallium complexes, [R3Sn{C(But)PCy}], R=Me or Bun and [IGa{C(But)PCy}2], have been prepared by similar routes. The reaction of the Grignard reagent with PhSeCl has afforded a new λ5,λ5-diphosphete, [{(But)CP(Cy)(SePh)}2], the mechanism of formation of which is discussed. The preparation of a phosphavinyl selenium compound, [(C8H4O2N)PC(But)(SePh)], is also described. All compounds have been spectroscopically characterised and several have been crystallographically authenticated.

Reactions of bulky alkyl lithium reagents with a phosphaalkyne (PCBut): synthesis and structural characterisation of a mixed valent phosphorus cage compound, PIII{μ-C(H)(But)}2{μ-C(H)(SiMe3)Si(Me)2C(H)2}PVC(SiMe3)2, and a phosphaalkenyl-substituted η3-azaallyl-lithium complex, [Li(tmeda){C(SiMe3)(2-NC5H3Me-6)[PC(But)(SiMe3)]}]

The reactions of the phosphaalkyne, P=CBu t , with the bulky alkyl lithium reagents, [LiCH 3 n (SiMe 3 ) n ] n = 1-3 and [LiC(SiMe 3 ) 2 (2-NC 5 H 3 Me-6)], have been investigated. These have led to unexpected results which include the formation of the mixed valent phosphorus cage compound, P I I I {μ-C(H)(Bu t )} 2 {μ-C(H)(SiMe 3 )Si(Me) 2 C(H) 2 }P V -C(SiMe 3 ) 2 , and the phosphaalkenyl-substituted η 3 -azaallyl-lithium complex, [Li(tmeda){C(SiMe 3 )(2-NC 5 H 3 Me-6)[P-C(Bu t )(SiMe 3 )]}], both of which have been crystallographically characterised. A mechanism for the formation of each complex has been discussed.

Structural Analogues of Bioactive Phosphonic Acids: First Crystal Structure Characterization of Phosphonothioic and Boranophosphonic Acids

Phosphonothioic and boranophosphonic acids have been structurally characterized for the first time by single X-ray crystallography. These two functional groups, and the corresponding phosphonic acid, were all conveniently synthesized in high yields from trityl H-phosphinic acid (Ph3CPO2H2). The resulting trityl-substituted series: Ph3CP(O)(OH)2, Ph3CP(S)(OH)2, Ph3CP(O)(BH3 −)(OH)]LH+ (L = Lewis base) is fully characterized by spectroscopic methods, and the structural characteristics are compared. The results indicate that boranophosphonic acids should be investigated anytime a bioactive phosphonic acid has been identified. The solid state arrangements of the synthesized compounds are also discussed.

Effects of the alkali metal counter ions on the germanium-germanium double bond length in a heavier group 14 element ethenide salt.

The first, well-characterized 1,2-dilithium salt of a group 14 element ethenide species, [[(dioxane)(0.5)(Et2O)LiGeC6H3-2,6-Mes2]2]infinity, shows that the positions of the cations have a large effect on the length of the Ge-Ge double bond.

The structural characterization of YbI2(DME)3

The preparation and structural characterization of [YbI2(DME)2] are reported. The complex crystallizes in the triclinic space group P 1¯: a = 13.0094 (10), b=14.504(3), c = 14.668 (3) Å, α = 115.281(10) β = 106.74(2), γ = 105.97(2)°. The metal center of the complex exhibits a distorted pentagonal bipyramidal coordination geometry which involves a rare example of a monodentate DME ligand.