Zinc 3,5-dimethylpyrazolate complexes: synthesis and structural studies. The crystal and molecular structure of [Zn2(dmpz)4(Hdmpz)2]

1990 ◽  
Vol 68 (9) ◽  
pp. 1494-1498 ◽  
Author(s):  
Martin K. Ehlert ◽  
Steven J. Rettig ◽  
Alan Storr ◽  
Robert C. Thompson ◽  
James Trotter

Zinc metal reacts with excess 3,5-dimethylpyrazole (Hdmpz) in the presence of O2 to produce materials of composition Zn(dmpz)2(Hdmpz)y. Thermolysis of these materials results in the loss of Hdmpz and the formation of the [Zn(dmpz)2]x polymer. Under appropriate conditions the pure dimer [Zn2(dmpz)4(Hdmpz)2] can be obtained in high yield. Crystals of bis[μ-(3,5-dimethylpyrazolyl-N1,N2)]bis[(3,5-dimethylpyrazolyl)(3,5-dimethylpyrazole)zinc(II)] are orthorhombic, a = 17.009(2), b = 29.239(2), c = 13.590(2) Å, Z = 8, space group Fddd. The structure was solved by heavy atom methods and was refined by full-matrix least-squares procedures to R = 0.037 and Rw = 0.042 for 913 reflections with I ≥ 3σ(I). The structure of [Zn2(dmpz)4(Hdmpz)2] contains nearly planar doubly dmpz bridged Zn2 units capped at each end by strongly hydrogen-bonded [Formula: see text] units. The zinc atoms display pseudotetrahedral coordination geometry with Zn—N = 1.991(3) (bridging) and 2.025(3) Å (terminal), and N—Zn—N = 99.6(2)–113.8(2)°. Keywords: zinc 3,5-dimethylpyrazolate complexes, crystal structure.

1988 ◽  
Vol 66 (3) ◽  
pp. 355-358 ◽  
Author(s):  
Steven J. Rettig ◽  
Alan Storr ◽  
James Trotter

Crystals of [dimethyl(1-pyrazolyl)(2-pyridylmethoxy)gallato-N2,O,N3](η3-allyl)dicarbonylmolybdenum(II) are triclinic, a = 9.632(2), b = 9.798(2), c = 10.255(2) Å, α = 80.16(1), β = 87.38(1), γ = 81.75(1)°, Z = 2, space group [Formula: see text]. The structure was solved by conventional heavy-atom methods and was refined by full-matrix least-squares procedures to R = 0.033 and Rw = 0.037 for 3000 reflections with I ≥ 3σ(I). The molecule has pseudo-octahedral coordination geometry with the tridentate [Me2Ga(N2C3H3)(OCH2(C5H4N))]− ligand facially coordinated and the η3-allyl ligand occupying one coordination site trans to the pyridyl nitrogen atom. Important bond lengths are Mo—O = 2.219(2), Mo—N(py) = 2.212(3), Mo—N(pz) = 2.232(2), Mo—C(allyl) = 2.290(4), 2.189(4), 2.341(4), Mo—CO (trans to O) = 1.928(4), and Mo—CO (trans to N) = 1.952(4) Å.


1989 ◽  
Vol 67 (11) ◽  
pp. 1959-1963 ◽  
Author(s):  
Wolfgang Kliegel ◽  
Steven J. Rettig ◽  
James Trotter

The reaction of N,N′-dihydroxy-N,N′-dimethylmethanediamine with phenylboronic acid leads to the product 1,7-dimethyl-3,5-diphenyl-2,4,6-trioxa-7-aza-1-azonia-3-bora-5-boratabicyclo[3.3.0]octane rather than the expected product 1,5-dimethyl-3-phenyl-1,5-diaza-2,4-dioxa-3-boracyclohexane. The structure of N,N′-dihydroxy-N,N′-dimethylmethanediamine has been determined and is discussed in terms of its reaction with PhB(OH)2. Crystals of N,N′-dihydroxy-N,N′-dimethylmethanediamine are tetragonal, a = 8.5346(3), c = 8.4178(7) Å, Z = 4, space group P421c. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to a final R of 0.036 and Rw of 0.038 for 333 reflections with I ≥ 3σ(I). The structure consists of hydrogen-bonded dimers having exact [Formula: see text] symmetry. Keywords: N,N′-dihydroxy-N,N′-dimethylmethanediamine, crystal structure.


1977 ◽  
Vol 55 (6) ◽  
pp. 958-965 ◽  
Author(s):  
Steven J. Rettig ◽  
James Trotter

Crystals of L-prolinatodiphenylboron are monoclinic, a = 5.9427(5), b = 14.4633(7), c = 8.9654(4) Å, β = 98.423(8)°, Z = 2, space group P21. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to a final R of 0.037 and Rw of 0.053 for 1477 reflections with I ≥ 3σ(I). The proline ring exhibits conformational disorder. The crystal structure consists of discrete molecules linked by N—H … O hydrogen bonds (N … O = 2.893(3) Å) along the short a axis. Intramolecular N—B coordination occurs to form a system of two fused five-membered rings. Bond lengths (corrected for libration) are: N—B, 1.630(3), O—B, 1.529(3), O—C, 1.219(3) and 1.300(3), N—C, 1.506(3) and 1.507(3), C(sp3)–C(sp3), 1.525(4), C(sp2)—C(sp3), 1.517(3), and mean C—C(phenyl), 1.394 Å.


1994 ◽  
Vol 72 (4) ◽  
pp. 1154-1161 ◽  
Author(s):  
Wolfgang Kliegel ◽  
Gottfried Lubkowitz ◽  
Steven J. Rettig ◽  
James Trotter

Three 2-(hydroxyamino)alkanols have been reacted with sterically hindered arylboronic acids, ArB(OH)2. When Ar = o-tolyl, 1:2 condensates having bicyclic structures are formed but when Ar = mesityl (2,4,6-(CH3)3C6H2), 1:1 condensates having six-membered cycloboronate structures result. These 1:1 condensates represent the first examples of N-unsubstituted 1,3-dioxa-4-aza-2-boracyclohexane derivatives. An X-ray analysis of one example provides unambiguous proof of the structure. Crystals of 2-mesityl-6,6-pentamethylene-1,3-dioxa-4-aza-2-boracyclohexane, 3c, are monoclinic, a = 11.076(9), b = 23.94(2), c = 13.414(9) Å, β = 109.40(5)°, Z = 8, space group P21/n. The structure was solved by direct methods and refined by full-matrix least-squares procedures to R = 0.051 and Rw = 0.058 for 2037 reflections with I ≥ 3σ(F2).


1992 ◽  
Vol 70 (9) ◽  
pp. 2329-2334 ◽  
Author(s):  
William R. Cullen ◽  
Steven J. Rettig ◽  
Tu Cai Zheng

The reaction of Os3(CO)10(MeCN)2 with PFc2Ph (Fc = (η-C5H4)Fe(η-C5H5)) affords the unsymmetrical isomer of 1,2-Os3(CO)10(PFc2Ph)2, 2. Crystals of 2 are monoclinic, a = 27.846(4), b = 11.253(4), c = 38.520(3) Å, β = 107.813(9)°, Z = 8, space group C2/c. The structure was solved by heavy atom methods, and was refined by full-matrix least-squares procedures to R = 0.030 and Rw = 0.027 for 5073 reflections with I ≥ 3σ(I).


1975 ◽  
Vol 53 (10) ◽  
pp. 1393-1401 ◽  
Author(s):  
Steven J. Rettig ◽  
James Trotter

Crystals of B-phenyl-dictychboroxazolidine are monoclinic, a = 8.4977(4), b = 9.0617(5), c = 7.0105(3) Å, β = 111.627(3)°, Z = 2, space group P21. The structure was solved by direct methods and was refined by full-matrix least squares procedures to a final R of 0.040 for 967 reflections with I ≥ 3σ(I). The bond lengths involving nonhydrogen atoms have been corrected for thermal motion. Bond lengths are: B—O, 1.460(3) and 1.474(3), B—N, 1.666(3), B—C, 1.613(3), C—O, 1.411(3) and 1.419(3), C—N, 1.485(3) and 1.486(3), C(sp3)—C(sp3), 1.514(4) and 1.524(4), C—C(ar), 1.384–1.400(4–6), mean C—H, 0.98(4), and N—H, 0.87(5) Å. The crystal structure consists of discrete molecules of B-phenyl-diptychboroxazolidine each linked to two others by N—H … O hydrogen bonds (O … N = 2.914(3) Å) to form continuous spirals along b.


1975 ◽  
Vol 53 (5) ◽  
pp. 765-776 ◽  
Author(s):  
Steven J. Rettig ◽  
James Trotter

Crystals of (±)-7,7-(2′,2′-dimethyl)pentamethylene-1-methyl-norbornane-2-oxime are monoclinic, a = 9.202(2), b = 12.852(3), c = 12.698(3) Å, β = 110.83(2)°, Z = 4, space group P21/c. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to a final R of 0.048 for 1538 reflections with I ≥ 3σ(I). The crystal structure consists of pairs of molecules linked by N … H—O hydrogen bonds (N … O = 2.821(3) Å ) to form centrosymmetric dimers. Bond distances are as follows: C—N = 1.266(3), N—O = 1.426(3), mean C(sp3)—C(sp3) = 1.540, and mean C(sp3)—C(sp3) = 1.511 Å.


1994 ◽  
Vol 72 (7) ◽  
pp. 1735-1740 ◽  
Author(s):  
Wolfgang Kliegel ◽  
Dierk Nanninga ◽  
Ulf Riebe ◽  
Steven J. Rettig ◽  
James Trotter

Oxime diarylborinates, 4, were obtained from several aliphatic and aromatic aldoximes as well as from cyclic ketoximes by acylation with a diarylborinic acid or anhydride (R2B-X, R = aryl, X = OH or OBR2). Compounds 4 could also be synthesized by condensation of an (aminoxy)-diarylborane, which supposedly has a cyclodimeric BONBON structure, with an aldehyde or with a ketone. Crystals of 3,3,6,6-tetrakis(4-methoxyphenyl)-2,5-diethylidene-1,4-dioxa-2,5-diazonia-3,6-diboratacyclohexane, 4b, are monoclinic, a = 7.9182(9), b = 19.7582(9), c = 9.6779(8) Å, β = 91.598(8)°, Z = 2, space group P21/n. The structure was solved by direct methods and refined by full-matrix least-squares procedures to R = 0.033 and Rw = 0.034 for 2344 reflections with I ≥ 3σ(F2). A dimeric structure featuring a central six-membered BONBON ring has been established for the oxime diarylborinate 4b. This represents the first structurally characterized example of a monocyclic BONBON ring.


1988 ◽  
Vol 66 (8) ◽  
pp. 2072-2078 ◽  
Author(s):  
Ramesh M. Belani ◽  
Brian R. James ◽  
David Dolphin ◽  
Steven J. Rettig

The complex (5, 10, 15, 20-tetraphenylporphinato)bis(tri-n-butylphosphine)iron(II), 1, has been isolated in a triclinic crystal form, a = 12.499(3), b = 12.528(2), c = 12.039(2) Å, α = 116.39(1), β = 109.79(1), γ = 98.13(1)°, Z = 1, space group [Formula: see text]. The structure was solved by conventional heavy atom methods and was refined by full-matrix least-squares procedures to R = 0.060 and Rw = 0.070 for 3551 reflections with I ≥ 3σ(I). The molecule, which has crystallographic [Formula: see text], symmetry, displays a relatively undistorted pseudo-octahedral coordination geometry with Fe—P = 2.346(1) and Fe—N = 1.998(3) and 1.993(3) Å. In CH2Cl2 solution, 1 reacts with CO and aldehydes to generate the carbonyl(phosphine) derivative, and decarbonylation of phenylacetaldehyde to toluene becomes catalytic under an Ar stream. The aldehyde decarbonylations involve radical pathways via carbonyl loss from [Formula: see text]. The hydrogen abstraction/initiation reaction probably utilizes trace O2 (and possibly trace (water); speculative mechanisms are discussed.


1985 ◽  
Vol 63 (3) ◽  
pp. 703-707 ◽  
Author(s):  
Brenda M. Louie ◽  
Steven J. Rettig ◽  
Alan Storr ◽  
James Trotter

Crystals of fac-[dimethylbis(1-pyrazolyl)gallato-N,N′](triphenylphosphine)tricarbonylrhenium(I) are triclinic, a = 9.479(2), b = 16.258(4), c = 20.412(6) Å, α = 110.06(1), β = 95.46(1), γ = 92.65(2)°, Z = 4, space group [Formula: see text] The structure was solved by conventional heavy-atom methods and was refined by full-matrix least-squares procedures to R = 0.027 and Rw = 0.031 for 5965 reflections with I ≥ 3σ(I). The two crystallographically independent molecules have nearly identical structures. The coordination about Re is distorted fac-octahedral with mean bond lengths: Re—P = 2.538(4), Re—N = 2.201(5), Re—CO(trans to P) = 1.931(1), and Re—CO(trans to N) = 1.913(9) Å. The ReGaN4 chelate rings have twisted boat conformations with cross-ring [Formula: see text] separations of 3.9396(7) and 3.8981(8) Å.


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