Eileen N. Duesler

Structural and Spectroscopic Characterization of an Electrophilic Iron Nitrido Complex

We have isolated and structurally characterized a terminal iron nitrido complex supported by a bulky tris(carbene)borate ligand. The electronic structure of this complex reveals that the a1 LUMO (formerly Fe(dz2)) is strongly stabilized by reduced antibonding interactions with the carbene sigma-donor ligands and configurational mixing (hybridization) with higher lying Fe 4s and 4p atomic orbitals. This unusual bonding interaction results in a low-lying Fe nitrido acceptor orbital (LUMO) that possesses electrophilic character. Reaction with PPh3 results in nitrogen atom transfer to the phosphine, supporting a reaction mechanism involving nucleophilic attack of the triphenylphosphine HOMO at the electrophilic LUMO of the iron nitrido complex.

Synthesis and crystal and molecular structures of diisopropyl N,N-diethylcarbamylmethylenephosphonate samarium nitrate and erbium nitrate complexes

Abstract Bis[diisopropylN,N-diethylcarbamylmethylenephosphonate] samarium(III) nitrate, Sm[(i-C3H7O)2P(O)CH2C(O)N(C2H5)2]2(NO3)3 3 and bis[diisopropyl N,N-diethylcarbamylmethylenephosphonatel]- erbium(III) nitrate monohydrate, Er[(i-C3H7O)2P(O)CH2C(O)N(C2H5)2]2(NO3)·(H2O) 4 have been prepared from the combination of an ethanolic solution of Sm(NO3)3·5H2O or Er(NO3)3·5H2O with phosphonate ligand. The resulting complexes were isolated and characterized by infrared and 1H, 13C1H and 31P1H NMR Spectroscopies. In addition, single crystal X-ray analyses of 3 and 4 have been completed. The structure of 3 was determined at −17°C from 7634 independent reflections obtained with a computer automated diffractometer. The complex crystallizes in the monoclinic space group C2/c with a = 25.672(10) A, b = 11.431(5) A, c = 18.731(5) A, β = 133.73(2)°, Z = 4, V = 3971.5 A3 and ϱcalcd = 1.50 g cm−3. The structure was solved with standard heavy atom methods and blocked least squares refinement of the structure converged with RF = 5.6% and RwF = 5.7%. The crystal contains monomeric units of 3 which have crystallographic C2 symmetry. The samarium atom is bonded to both carbonyl and phosphoryl oxygen atoms of two phosphonate ligands and the oxygen atoms of three bidentate nitrate ions. The overall coordination number of the samarium atom is ten. Several important bond distances include SmO (carbonyl) 2.433(2) A, SmO (phosphoryl) 2.418(3) A, SmO (nitrate)avg 2.589(5) A, PO (phosphoryl) 1.480(2) A and CO (carbonyl) 1.261(3) A. The structure of 4 was determined at 25°C from 8432 independent reflections. The compound crystallizes in the triclinic space group P 1 with a = 11.590(2) A, b = 12.321(2) A, c = 14.840(4) A, α = 97.40(2)°, β = 91.85(2)°, λ = 95.17(1)°, Z = 2, V = 2090.9 A3 and ϱcalcd = 1.48 g cm−3. The structure was solved by standard heavy atom methods and final discrepancy indices RF = 7.7% and RwF = 7.6% were obtained. The erbium atom is bonded to the phosphoryl oxygen atoms of two phosphonate ligands, the oxygen atoms of three bidentate nitrate ions and the oxygen atom of a water molecule. The carbonyl oxygen atoms are hydrogen bonded to the hydrogen atoms of the coordinated water and the erbium atom coordination number is nine. Several important bond distances include ErO (phosphoryl)aug 2.275(6) A, ErO (nitrate)aug 2.435(8) A, ErO (water) 2.302(7) A, PO (phosphoryl) 1.479(6) and 1.452(7) A and CO (carbonyl) 1.240(11) and 1.239(11) A.

The chemistry of β-diketonate copper(I) compounds—III. The synthesis of (β-diketonate) Cu(1,5-COD) compounds, the solid state structure and disproportionation of hexafluoroacetylacetonato (1,5-cyclooctadiene)copper(I), (hfac)Cu(1,5-COD)

Abstract The compounds (β-diketonate)Cu(1,5-COD) have been prepared by the reaction between [(1,5-COD)CuCl]2 and Na(β-diketonate) for β-diketonate = hexafluoroacetylacetonate (hfac), trifluoroacetylacetonate (tfac) and acetylacetonate (acac) and 1,5- COD = 1,5-cyclooctadiene. These compounds were characterized spectroscopically and (hfac)Cu(1,5-COD) was characterized, in the solid state, by single-crystal X-ray diffraction. Crystal data: empirical formula, C13,H13CuF6O2; crystal system, monoclinic; space group, P21/c; a = 10.011(2), b = 9.777(3), c = 15.658(3) A and β = 107.88(2)° and Z = 4. The coordination of the copper centre is best described as “3+1” with an asymmetrically coordinated 1,5-COD ligand where the Cu:C(6):C(7) centroid and Cu:C(10):C(11) centroid distances are 1.953 and 2.418 A, respectively. The quantitative disproportionation, according to the equation 2(hfac)Cu(1,5-COD) → Cu+Cu(hfac)2+2(1,5-COD) to produce copper metal and volatile by-products, was observed at 200°C.

Formation and crystal and molecular structures of dioxouranium(VI) complexes containing bidentate carbamoylmethylphosphinate and phosphine oxide ligands

Abstract The ligands (C 6 H 5 )(C 2 H 5 O)P(O)CH 2 C(O)N(C 2 H 5 ) 2 ( 1 ) and (C 6 H 5 ) 2 P(O)CH 2 C(O)N(C 2 H 5 ) 2 ( 2 ) have been prepared and characterized by spectroscopic methods, and the coordination complexes, UO 2 (NO 3 ) 2 [(C 6 H 5 )(C 2 H 5 O)P(O)CH 2 C(O)N(C 2 H 5 ) 2 ] ( 3 ) and UO 2 (NO 3 ) 2 [(C 6 H 5 ) 2 P(O)CH 2 C(O)N(C 2 H 5 ) 2 ] ( 4 ), have been isolated and characterized by elemental analyses and spectroscopic methods. A single crystal X-ray diffraction analysis of 3 has been completed at 20 °C, and the complex crystallizes in the monoclinic space group P 2 1 / n with a = 13.141(3) A, b = 13.281(2) A, c = 13.918(3) », β= 116.79(2)°, Z = 4, V = 2168.5(8) A 3 , and ϱ calcd = 2.07 g×cm −3 . The structure was solved by heavy-atom methods and blocked least-squares refinement converged with R F = 0.048 and R wF = 0.046. Single crystal X-ray diffraction analysis of 4 has been performed at 26 °C and the complex crystallizes in the monoclinic space group P 2 1 / n with a = 11.155(3) A, b = 11.265(2) A, c = 20.317(5) A, β = 107.44(2)°, Z = 4, V = 2435.5(8) A 3 and ϱ calcd = 1.93 g×cm −3 . The structure was solved by heavy atom methods and blocked least-squares refinement converged with R F , = 0.035 and R wF = 0.029. The molecular structures contain linear UO2 2+ ions bonded to two bidentate nitrate ions and one bidentate carbamoylmethylphosphinate or phosphine oxide ligand. The structures of these complexes are compared with the structure of UO 2 (NO 3 ) 2 [(i-C 3 H 7 O) 2 P(O)CH 2 C(O)N(C 2 H 5 ) 2 ].

Synthesis of Silylborazines and Their Utilization as Precursors to Silicon‐Containing Boron Nitride☆

The reactions of LiSi(SiMe3)3 with Cl(Me)2B3N3(Me)3, Cl2(Me)B3N3(Me)3, (ClBNMe)3, and (ClBNH)3 result in the formation of molecular species (Me3Si)3Si(Me)2B3N3(Me)3, [(Me3Si)3Si]2(Me)B3N3(Me)3, [(Me3Si)3SiBNMe]3, and [(Me3-Si)3SiBNH]3. The new compounds have been characterized by spectroscopic techniques, and a single-crystal X-ray diffraction analysis for [(Me3Si)3SiBNMe]3 has been completed. The monomer (Me3Si)3Si(Cl)2B3N3H3 was also prepared and combined with (Me3Si)2NH in hexane to form an organic solvent soluble oligomer. Pyrolysis of this oligomer provides composites containing BN and an SiXNYCZ phase that suppresses the crystallization of BN.

Synthesis and molecular structures of complexes of bismuth(III) nitrate with tridentate ligands : 2,6-BIS(-CH2 P((O)R2) substituted pyridine-N-oxides

Abstract The two trifunctional ligands 2,6-(Ph,P(O)—CH2)2C5H3NO (1) and 2,6[(EtO)2P(O)—CH2]2C5H3NO (2) were prepared by Arbuzov reactions on 2,6-bis (chloromethyl)pyridine with Ph2POMe and triethylphosphite, respectively, and characterized by spectroscopic methods and X-ray structural analysis (1). Their coordination chemistry with Bi(NO3)3 was studied. The complexes Bi(NO3)3·1·DMF and Bi (N03)3·2 were isolated and their X-ray structures determined. In both cases, the ligands bind in a tridentate fashion to BiIII, and the nitrate ions remain in the inner coordination sphere. Structural features of the unbound and bound ligand I are discussed.

Synthesis and characterization of 1,1,1,5,5,5-hexafluoroacetylacetonato-(1,5-cyclooctadiene)silver(I) dimer. An unusual β-diketonate coordination mode

Abstract The compound (hfac)Ag(1,5-cod) was synthesized by the reaction of 1,1,1,5,5,5-hexafluoroacetylacetone (hfacH) with Ag2O and 1,5-cyclooctadiene (1,5-cod) and characterized in the solid state by single-crystal X-ray diffraction. In contrast to the corresponding copper(I) compound (hfac)Ag(1,5-cod) exhibited lower volatility and was found to be dimeric in the solid state, containing the two unusual β-diketonate coordination modes, namely, μ4-η2-hfac and μ2-hfac. The deterioration of the crystal and extensive disorder precluded a detailed comparison of the metrical parameters of this compound with other literature data. However, the solid-state FTIR data showed substantial differences in the ν(CO) and ν(CC) stretching regions compared with the chelated hfac ligand in (hfac)Cu(1,5-cod). These data will be useful in assigning the coordination mode of β-diketonate ligands in metal-organic β-diketonate complexes by FTIR.

Preparation of volatile, monomeric copper(I) β-diketonate complexes

Abstract A series of (β-diketonate)Cu(PMe3), where β-diketonate = acetylacetonate (acac) (1), trifluoroacetylacetonate (2) and hexafluoroacetylacetonate (3), compounds have been prepared by the reaction of β-diketones with (η5-C5H5)CuPMe3. A single crystal X-ray diffraction study of (tfa)CuPMe3 reveals that it is monomeric in the solid state with a trigonal planar copper coordination environment. All three new compounds are volatile and soluble in hydrocarbon solvents.

The acidity and coordination properties of carbamylmethylenephosphonate ligands: Synthesis and molecular structure of dialkyl N,N-diethylcarbamylmethylenephosphonate mercury(II) nitrate complexes

Abstract The acidity and coordination properties of carbamylmethylenephosphonate ligands (RO) 2 P(O)CH 2 C(O)N(C 2 H 5 ) 2 , R = C 2 H 5 , i-C 3 H 7 , n-C 4 H 9 and n-C 6 H 13 , have been investigated. The reactions of the ligands with Na or NaH in benzene, hexane or THF result in the formation of the anionic bases (RO) 2 P(O)CHC(O)N(C 2 H 5 ) − 2 which have been characterized by the spectroscopic methods. Dialkyl N,N-diethylcarbamylmethylenephosphonate mercury(II) nitrate complexes, Hg[(RO) 2 P(O)CHC(O)N(C 2 H 5 ) 2 ](NO 3 ), have been prepared from the combination of acidic aqueous Hg(NO 3 ) 2 and the respective neutral phosphonate ligands in hexane or benzene and characterized by infrared and 1 H, 13 C{ 1 H} and 31 P NMR spectroscopy. The crystal and molecular structure of diethyl N,N-diethylcarbamylmethylenephosphonate mercury(II) nitrate, [Hg(DEDECMP-H)NO 3 ] C 10 H 21 N 2 O 7 PHg, was determined at −40 °C from 5914 independent reflections obtained with a computer automated diffractometer. The compound crystallizes in the triclinic space group P 1 with a = 9.631(3) A, b = 9.656(3) A, c = 9.866(3) A, α = 67.31(3)°, β = 77.22(3)°, γ = 77.24(3)°, Z = 2, V = 816.2(5) A 3 and ϱ calc = 2.09 g cm −3 . The structure was solved by standard heavy atom methods and blocked least squares refinement of the structure converged with R F = 7.6%, R wF = 7.4%. The crystals contain dimeric [Hg(DEDECMP-H)NO 3 ] 2 units with each Hg atom σ bonded to the central methine carbon atom of one anionic phosphonate ligand, to two oxygen atoms of one nitrate group and to the carbonyl and phosphoryl oxygen atoms of the phosphonate ligand which is carbon bonded to the second mercury atom. Several important bond distances include the mercury atom–methine carbon atom distance Hg(1)C(1) 2.110(10) A, the mercury atom–nitrate oxygen atom distances Hg(1)O(5) 2.134(11) A and Hg(1)O(6) 2.797(12) A, the phosphoryl distance P(1)O(1) 1.460(7) A and the carbonyl distance C(2)O(4) 1.269(10) A. The Hg atom interaction distance with the second (DEDECMP-H) ligand are Hg(1)O(1′) 2.483(6) A and Hg(1)O(4′) 2.504(6) A.

Laurencienyne, a new acetylenic cyclic ether from the marine red alga laurencia obtusa

Abstract The structure and absolute stereochemistry of laurencienyne, a non-isoprenoid cyclic ether isolated from Laurencia obtusa , has been established by X-ray and spectroscopic studies.