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Regioselective reactivity, molecular cleft selectivity, and conformational properties have been examined in the skeletally stabilized triphosphazanes C 6 H 4 N 2 [P(NEt 2 ) 2 ] 2 PNEt 2 (4), C 6 H 4 N 2 -[P(S)(NEt 2 ) 2 ] 2 PCl (5), and C 6 H 4 N 2 [P(S)(NEt 2 ) 2 ] 2 P(S)NEt 2 (9) and in a series of new derivatives. 3 is oxidized/coordinated regioselectively by O 3 , Se, PhN 3 , and BH 3 to C 6 H 4 N 2 [P(O)(NEt 2 ) 2 ] 2 PNEt 2 and C 6 H 4 N 4 [P(O)(NEt 2 ) 2 ] 2 P(O)NEtz

Siladiazoles C 6 H 4 (NH) 2 SiPb 2 (7) and C 6 H 4 (NH) 2 SiPbMe (8) and cyclic siloxazanes C 6 H 4 (NHSiPh 2 ) 2 O (9) andC 6 H 4 (NHSiPbMe) 2 O (IOA/IOB) are obtained from reactions of 1,2-(NH 2 ) 2 C 6 H 4 with Ph 2 SiCl 2 , PhMeSiCl 2 , (Ph 2 SiCl) 2 O, and (PbMeSiCl) 2 O, respectively

Trifunctional ligands, 1-phosphono-1-carbamoyl-n-alkyl ester alkanes [(RO)2P(O)][C(O)NEt2]C(H)[(CH2)nC(O)OR′] (n=1−3) were prepared from metathesis reactions of the metallated anions [(RO)2P(O)][C(O)NEt2]CH− and bromoalkyl esters. The ligands were fully characterized and selected coordination chemistry with La(III), Er(III), UO22+ and Th(IV) was examined. The molecular structures of three coordination complexes were determined by single crystal X-ray diffraction techniques. The 1:1 complex, Er(NO3)3{[(i- PrO)2P(O)][C(O)NEt2]CH[(CH2)2C(O)OMe]}, crystallizes in the monoclinic space group, P21/c with a=9.418(4), b=15.547(7), c=18.259(8) A, β=92.29(4)°, Z=4, V=2671(2) A3 and ϱcalc=1.787 g cm−3. The structure was solved by heavy atom methods and full matrix least-squares refinements converged at RF=3.52% and RwF=4.84% on 4086 reflections with F>6σ(F). The compound forms a polymeric structure in which each Er(III) is nine- coordinate. The Er atom is bonded to three bidentate nitrate ions and the bidentate carbamoylmethyl phosphonate fragment of one trifunctional ligand. It is also bridge bonded to the ester carbonyl group in a second molecular unit. The 2:1 complex, Er(NO3)3{[(i-PrO)2P(O)][C(O)NEt2]CH[(CH2)2C(O)OMe]}2, crystallizes in the monoclinic space group P21/n with a=16.090(8), b=19.114(9), c=17.166(8) A, β=108.01(4)°, Z=4, V=5021(4) A3 and ϱcalc=1.434 g cm−3. The structure was solved by direct methods and refinement converged at RF=4.00% and RwF=4.89% on 5109 independent reflections with F>6σ(F). The compound contains isolated molecules in which the Er(III) is nine-coordinate and bonded to three bidentate nitrate ions, the bidentate carbamoylmethyl phosphonate fragment of one ligand and the phosphonate of a second ligand. The 1:1 complex, UO2(NO3)2{[(i- PrO)2P(O)][C(O)NEt2]CH[(CH2)3C(O)OEt]}, crystallizes in the monoclinic space group P21/c with a=8.855(2), b=16.257(5), c=20.603(6) A, β=92.07(2)°, Z=4, V=2964(1) A3, ϱcalc=1.765 g cm−3. The structure was solved by direct methods and refinement converged at RF=7.82% and RwF=7.77% on 3906 independent reflections with F>3σ(F). The compound contains a linear UO22+ ion bonded to two bidentate nitrate ions and the bidentate carbamoylmethyl phosphonate fragment of the trifunctional ligand. The structures of these complexes are compared with structural data for complexes containing related 1-phosphono-1-carbamoyl-n-carbamoyl alkanes and 1,1-bis- phosphono-n-carbamoyl alkanes.

Trifunctional ligands, 1-phosphono-1-carbamoyl-n-alkyl ester alkanes [(RO)2P(O)][C(O)NEt2]C(H)[(CH2)nC(O)OR′] (n=1−3) were prepared from metathesis reactions of the metallated anions [(RO)2P(O)][C(O)NEt2]CH− and bromoalkyl esters. The ligands were fully characterized and selected coordination chemistry with La(III), Er(III), UO22+ and Th(IV) was examined. The molecular structures of three coordination complexes were determined by single crystal X-ray diffraction techniques. The 1:1 complex, Er(NO3)3{[(i- PrO)2P(O)][C(O)NEt2]CH[(CH2)2C(O)OMe]}, crystallizes in the monoclinic space group, P21/c with a=9.418(4), b=15.547(7), c=18.259(8) A, β=92.29(4)°, Z=4, V=2671(2) A3 and ϱcalc=1.787 g cm−3. The structure was solved by heavy atom methods and full matrix least-squares refinements converged at RF=3.52% and RwF=4.84% on 4086 reflections with F>6σ(F). The compound forms a polymeric structure in which each Er(III) is nine- coordinate. The Er atom is bonded to three bidentate nitrate ions and the bidentate carbamoylmethyl phosphonate fragment of one trifunctional ligand. It is also bridge bonded to the ester carbonyl group in a second molecular unit. The 2:1 complex, Er(NO3)3{[(i-PrO)2P(O)][C(O)NEt2]CH[(CH2)2C(O)OMe]}2, crystallizes in the monoclinic space group P21/n with a=16.090(8), b=19.114(9), c=17.166(8) A, β=108.01(4)°, Z=4, V=5021(4) A3 and ϱcalc=1.434 g cm−3. The structure was solved by direct methods and refinement converged at RF=4.00% and RwF=4.89% on 5109 independent reflections with F>6σ(F). The compound contains isolated molecules in which the Er(III) is nine-coordinate and bonded to three bidentate nitrate ions, the bidentate carbamoylmethyl phosphonate fragment of one ligand and the phosphonate of a second ligand. The 1:1 complex, UO2(NO3)2{[(i- PrO)2P(O)][C(O)NEt2]CH[(CH2)3C(O)OEt]}, crystallizes in the monoclinic space group P21/c with a=8.855(2), b=16.257(5), c=20.603(6) A, β=92.07(2)°, Z=4, V=2964(1) A3, ϱcalc=1.765 g cm−3. The structure was solved by direct methods and refinement converged at RF=7.82% and RwF=7.77% on 3906 independent reflections with F>3σ(F). The compound contains a linear UO22+ ion bonded to two bidentate nitrate ions and the bidentate carbamoylmethyl phosphonate fragment of the trifunctional ligand. The structures of these complexes are compared with structural data for complexes containing related 1-phosphono-1-carbamoyl-n-carbamoyl alkanes and 1,1-bis- phosphono-n-carbamoyl alkanes.

This paper reports gels containing a poly(borazinyl amine) and tetrahydrofuran processed by CO{sub 2} supercritical drying techniques followed by pyrolysis. The resulting BN ceramic aerogels are highly porous, and the microstructure, porosity, and surface area characteristics have been examined. The aerogels show excellent thermal stability exhibiting surface areas in excess of 350 m{sup 2}/g and porosities greater than 0.8 even when heated in argon at 1500{degrees}C for 8 h. By removing solvent via evaporation before supercritical drying, the mean pore radius can be varied between 3.6 and 10 nm.

Bifunctional and polyfunctional ligands are finding increasing applications in metal ion liquid-liquid extraction processes, and there is interest in developing more rational design parameters to assist in the construction of ion specific ligand systems. The design and synthesis of several new families of polyfunctional organophosphonate ligands are reviewed here along with studies of the coordination chemistry of the ligands with lanthanide and uranyl ions.

A method of preparation for boron nitride by deamination of a readily available borazene (HNB(NMe{sub 2})){sub 3} and conversion of the resulting solid polymer to h-BN is described. The ceramic powder obtained at 1200{degree}C was analyzed by transmission electron microscopy and energy-dispersive x-ray analysis. The results indicated crystalline BN with well-defined sharp lattice fringes and an electron-diffraction pattern consistent with the formation of crystalline BN. 19 refs.

Poly(borazinylamines) have been processed in THF and toluene solvents and aerogel forms produced by supercritical drying methods. The polymer aerogels have been pyrolyzed and porous amorphous and crystalline BN monoliths have been produced. These have been characterized and effects of processing factors on surface area and pore structure are described.

The structure of chlorobis(3-butenyldiphenylphosphino)rhodium(I) was determined by three-dimensional x-ray diffractometer techniques. The compound crystallizes in the space group P2/sub 1//c with cell constants of a = 10.697 (5) A, b = 9.832 (5) A, c , 36.44 (2) A, and ..beta.. = 96.42 (3)/sup 0/; Z= 4. The structure, solved by heavy-atom techniques, was refined by full-matrix least-squares methods using the 4218 reflections which had intensities 3 sigma above background to an unweighted R value of 5.1 percent. The coordination around the Rh(I) atom is best described as trigonal bipyramidal with one phosphorus and the midpoints of the two olefinic groups forming the equatorial plane which lies 0.13 A toward the Cl atom from Rh(I). In spite of the different geometric constraint imposed by the butenyl chains, both olefinic groups lie in the equatorial plane (within 8.5/sup 0/). This phenomenon and the placement of the best ..pi.. acceptor in the equatorial plane are interpreted in terms of a synergetic cooperation between the ..pi.. and sigma bonding in this plane.

Bifunctional and polyfunctional ligands are finding increasing applications in metal ion liquid-liquid extraction processes, and there is interest in developing more rational design parameters to assist in the construction of ion specific ligand systems. The design and synthesis of several new families of polyfunctional organophosphonate ligands are reviewed here along with studies of the coordination chemistry of the ligands with lanthanide and uranyl ions.

Reaction of 1,2-(NH2)2C6H4 with MeP(NEt2)2 yields the new 1,3,2-di-azaphosphole C6H4(NH)2PMe (1). 1 with cycloheptatriene·Mo(CO)3 yields fac-[C6H4(NH)2PMe]3Mo(CO)3 (2), which with Ph3PO from MeCN solution forms the cocrystallate [C6H4(NH)2PMe]3Mo(CO)3·Ph3PO·MeCN (3). New compounds are characterized by spectral data; an X-ray analysis of 3 confirms its structure.

The 11B NMR spectrum of B4H10 consists of a low‐field triplet exhibiting secondary triplet splitting and a high‐field doublet having extensive fine structure. A reinterpretation of this spectrum is proposed. The triplet structure arises from coupling of 11B in the BH2 groups to the two terminal protons and to the two adjacent bridge protons. The doublet can not be assigned from first‐order considerations. 11B–{1H} double resonance and 10B and 11B substitution studies indicate that the doublet fine structure arises from strong 11B–1H coupling interactions. The signs of JBH and JBBH are shown to be opposite from a comparison of the observed and calculated 11B spectra of tetraborane samples with various 10B/11B isotopic ratios. The proton spectrum of B4H10 consists of a quartet on which is superimposed a broad feature plus several smaller peaks. The spectra calculated for the 11BH2, 10BH2, and BH terminal protons and the bridge protons account for all the peaks in the 1H spectrum. A difference in the ease of...

Kinetic studies of conversion of B4H10 to B5H11 are reported. The rate equation Rate = 6·5 × 1013 exp (−24300RT)(B4H10) is interpreted in terms of the two step reaction B4H10 → B4H8 + H2B4H8 + B2H6 → B5H11 + BH3 wherein the first step is rate limiting. Application of semitopological equations (modified to treat vacant orbital structures) leads to two satisfactory structures for B4H8.

The mass spectrum of trimethyl boron is reported and an analysis in terms of contributing ions is givem. Methyl migration from one molecule to another is shown not to occur under a wide range of experimental conditions.

Die Reaktion von im Lichtbogen erzeugten Kohlenstoffatomen mit Dimethylaminoboran, (CH3)2NBH2 (1), ergibt als Hauptreaktionsprodukt das Dimethylamino-methylboran, (CH3)2NBHCH3 (3), das sich mit dem Ausgangsmaterial zur Vierringverbindung 5 umsetzt. Weiterhin findet man Dimethylamino-dimethylboran, (CH3)2NB(CH3)2 (2) und Dimethylamin-boran, (CH3)2NHBH3. Schlieslich kann die bisher noch nicht bekannte Verbindung (CH3)2NBHOBHN(CH3)2 (6) isoliert werden. The Reaction of Boron-Nitrogen Compounds with Excited Carbon Atoms Generated in an Arc The interaction of carbon vapor from a carbon are with dimethylaminoborane, (CH3)2NBH2 (1), yields as the main reaction product (dimethylamino)methylborane, (CH3)2 NBHCH3 (3), which combines with the starting material to form the four-membered ring compound 5. Other compounds formed in this reaction are (dimethylamino)dimethylborane, (CH3)2NB(CH3)2 (2), and dimethylaminborane, (CH3)2NHBH3, as well as the previously unknown compound (CH3)2NBHOBHN(CH3)2 (6), which could be isolated.

The decomposition of B/sub 2/H/sub 6/ was shown to be five times faster than that of B/sub 2/D/sub 6/ by following the rate of hydrogen elimination. Factors affecting the concentration of one boron and three boron intermediates are discussed. The evidence is interpreted in terms of the reaction B/sub 3/H/ sub 9/ -B/sub 3/H/sub 7/ + H/sub 2/ as the rate controlling step of the decomposition. (auth)