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Hans-Georg Schmidt

Publications and source records attributed to Hans-Georg Schmidt.

13 recordsLinked to original sources
PubMed2003

Synthesis and x-ray crystal structure of [(THF)Zn(O(2)(OH)SiR)](4) (R = (2,6-i-Pr(2)C(6)H(3))N(SiMe(3))): enroute to larger aggregates.

Reaction of aminosilanetriol RSi(OH)(3) (1) (R = (2,6-i-Pr(2)C(6)H(3))N(SiMe(3))) with diethyl zinc at room temperature in 1:1 stoichiometric ratio affords [(THF)Zn(O(2)(OH)SiR)](4) (2) (R = (2,6-i-Pr(2)C(6)H(3))N(SiMe(3))) in good yield. The single-crystal X-ray diffraction studies reveal that 2 is monoclinic, P2(1), with a = 17.117(3) A, b = 16.692(5) A, c = 17.399(4) A, alpha = gamma = 90 degrees, beta = 91.45(7) degrees, and Z = 2. The molecular structure of 2 contains two puckered eight-membered Zn(2)Si(2)O(4) rings, which are connected by the Zn-O bonds and form two planar four-membered Zn(2)O(2) rings. Compound 2 contains an unreacted hydroxyl group on each silicon atom, and hence, we carried out the reactions of 2 with dimethylzinc and methyllithium to form [Zn(4)(THF)(4)(MeZn)(4)(O(3)SiR)(4)] (3) (R = (2,6-i-Pr(2)C(6)H(3))N(SiMe(3))) and [(L)ZnLi(O(3)SiR)](4) (4) (L = 1,4-(Me(2)N)(2)C(6)H(4), R = (2,6-i-Pr(2)C(6)H(3))N(SiMe(3))), respectively. This suggested that 2 could be an intermediate product formed during the synthesis of 3 and 4.

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PubMed2002

Synthesis and structures of [[HC(CMeNAr)(2)]Ge(S)X] (Ar = 2,6-iPr(2)C(6)H(3), X = F, Cl, Me): structurally characterized examples with a formal double bond between group 14 and 16 elements bearing a halide.

Treatment of [{HC(CMeNAr)2}GeX] (Ar = 2,6-iPr2C6H3, X = Cl (1), F (2)), with elemental sulfur at room temperature smoothly afforded the [{HC(CMeNAr)2}Ge(S)X] (X = Cl (3), F (4)). Compound 4 can also be obtained from 3 with the fluorination reagent Me3SnF. Reaction of 3 with MeLi led to the formation of [{HC(CMeNAr)2}Ge(S)Me] (5). Single-crystal X-ray structural analyses indicate compounds 3-5 are monomeric. The germanium centers adopt four coordinated sites and reside in distorted tetrahedral environment. Compounds 3 and 4 are structurally characterized examples with a formal double bond between group 14 and 16 elements bearing a halide.

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PubMed2002

Syntheses, structures, and surface aromaticity of the new carbaalane [(AlH)(6)(AlNMe(3))(2)(CCH(2)R)(6)] (R = Ph, CH(2)SiMe(3)) and a stepwise functionalization of the inner and outer sphere of the cluster.

The reaction of the acetylene RC triple bond CH (R = Ph, CH(2)SiMe(3)) with an excess of AlH(3).NMe(3) in boiling toluene leads to the carbaalane [(AlH)(6)(AlNMe(3))(2)(CCH(2)R)(6)] (R = Ph 1, CH(2)SiMe(3) 2) in good yield. Treatment of 2 with BCl(3) under varying conditions gives the chlorinated products [(AlCl)(6)(AlNMe(3))(2)(CCH(2)CH(2)SiMe(3))(6)] 3 and [(AlCl)(6)(AlNMe(3))(2)(CCH(2)CH(2)SiMe(2)Cl)(6)] 4, respectively. The latter clearly demonstrates that the cluster can be stepwise functionalized within the inner and outer sphere. The X-ray single-crystal structures of 1, 2, and 4 have been determined. All compounds have in common that the central core consists of a cluster having eight aluminum and six carbon atoms. The bonding properties in this cluster are described as a new manifestation of three-dimensional surface aromaticity. Each Al(4)C fragment of the cube is formed by four bonds with three electron pairs, thus leading to a strong delocalization of the electrons. A phenomenological modeling using a three-dimensional Hückel scheme with fitted parameters to reproduce the energies from ab initio calculations revealed that the orbital scheme localized at one Al(4)C fragment possesses an orbital sextet with a large HOMO-LUMO gap. This is in line with the criteria of aromaticity. The idea of aromaticity was sustained also by qualitative valence bond reasons enumerating the different resonance structures by means of graph theoretical methods.

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PubMed2002

Reactions of AlH(3) x NMe(3) with nitriles: structural characterization and substitution reactions of hexameric aluminum imides.

The reaction of AlH(3).NMe(3) with RCN proceeds with the evolution of trimethylamine and affords (HAINCH(2)R)(6) (R = Ph (1), p-MeC(6)H(4) (2), p-CF(3)C(6)H(4) (3)). Compounds 1 and 3 are characterized by single-crystal structural analysis. Compound 1 reacts with Me(3)SiBr as well as with PhC[triple bond]CH to give (XAINCH(2)Ph)(6) (X = Br (4), PhC[triple bond]C (5)). Structural data and other characterization data of compounds 4 and 5 show that all the hydridic hydrogen atoms in 1 have been replaced by bromine atoms and PhC[triple bond]C groups, respectively. Compounds 1-5 are potential precursors for the preparation of aluminum nitride. Crystals of 1 are rhombohedral, space group R3 macro, with a = 15.7457(13) A, b = 15.7457(13) A, c = 14.949(2) A, V = 3209.8(5) A(3), and Z = 3. Crystals of 3.(3)/(4)C(7)H(8) are triclinic, space group P1 macro, with a = 17.527(11) A, b = 18.894(12) A, c = 19.246(15) A, alpha = 96.11(7) degrees, beta = 102.23(4) degrees, gamma = 106.79(3) degrees, V = 5867(7) A(3), and Z = 4. Compound 4 crystallizes in the monoclinic space group P2(1)/c, with a = 14.175(4) A, b = 16.678(5) A, c = 10.731(3) A, beta = 106.82(2) degrees, V = 2428.6(11) A(3), and Z = 2. Compound 5. C(7)H(8) crystallizes in the monoclinic space group C2/c, with a = 25.842(5) A, b = 15.443(3) A, c = 20.699(4) A, beta = 105.88(3) degrees, V = 7945(3) A(3), and Z = 4.

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PubMed2000

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PubMed1997

Novel Cyclopentadienyl-Free Organolanthanides: The First Examples of Five-Membered Amidolanthanide Heterocycles.

Reactions of LnCl(3) (Ln = Nd, Gd, Yb) and [{Me(2)SiN(R)Li}(2)] (R = t-Bu, Ph) give the chloride-bridged dimers [{{(t-Bu)NSiMe(2)SiMe(2)N(t-Bu)}Ln(&mgr;-Cl)(THF)}(2)] (1, Ln = Nd; 2, Ln = Gd; 3, Ln = Yb) and [{{(Ph)NSiMe(2)SiMe(2)N(Ph)}Ln(&mgr;-Cl)(THF)(2)}(2)] (4, Ln = Nd; 5, Ln = Gd; 6, Ln = Yb) in good yields. Compounds 2 and 5 were structurally characterized by X-ray crystallography: 2, triclinic, P&onemacr;, a = 10.321(2) Å, b = 11.116(2) Å, c = 13.434(3) Å, alpha = 107.57(3) degrees, beta = 111.31(3) degrees, gamma = 90.67(3) degrees, V = 1356.1(5) Å(3), Z = 1, R = 0.0233; 5, monoclinic, P2(1)/n, a = 13.913(13) Å, b = 12.914(9) Å, c = 16.434(14) Å, beta = 105.64(3) degrees, V = 2843(4) Å(3), Z = 2, R = 0.0281. The chloro functions in 1-6 remain reactive, demonstrated by the isolation of the trifluoroacetate derivatives of 1 and 2. Treatment of 1 or 2 with 2 equiv of NaOCOCF(3) gives [{{(t-Bu)NSiMe(2)SiMe(2)N(t-Bu)}Ln(&mgr;-OCOCF(3))(THF)}(2)] (7, Ln = Nd; 8, Ln = Gd). The structure of 8 was determined by a single-crystal X-ray diffraction analysis. Crystal data for 8: triclinic, P&onemacr;, a = 11.045(2) Å, b = 16.120(3) Å, c = 16.949(3) Å, alpha = 66.17(3) degrees, beta = 85.51(3) degrees, gamma = 78.27(3) degrees, V = 2702.9(9) Å(3), Z = 2, R = 0.0311. The structure of 8 shows the trifluoroacetate group adopting a bridging bidentate mode of coordination.

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PubMed1996

Organometallic Fluorides of Zirconium and Hafnium in the Synthesis of Carboxylate Complexes: Molecular Structures of [{(eta(5)-C(5)Me(5))ZrF(OCOCF(3))(2)}(2)] and [(eta(5)-C(5)Me(5))(2)Zr(OCOCF(3))(2)].

The reaction of [(eta(5)-C(5)Me(5))ZrF(3)] and [(eta(5)-C(5)Me(5))HfF(3)] with Me(3)SiOCOCF(3) yields the dinuclear complexes [{(eta(5)-C(5)Me(5))ZrF(OCOCF(3))(2)}(2)] (1) and [{(eta(5)-C(5)Me(5))HfF(OCOCF(3))(2)}(2)] (2), regardless of the molar ratio employed. [(eta(5)-C(5)Me(5))(2)ZrF(2)] reacts with 1 and 2 equiv of Me(3)SiOCOCF(3) to form the mononuclear compounds [(eta(5)-C(5)Me(5))(2)Zr(OCOCF(3))(2)] (3) and [(eta(5)-C(5)Me(5))(2)ZrF(OCOCF(3))] (4), respectively. The molecular structures of 1 and 3 have been determined by single-crystal X-ray analysis: 1, triclinic, P&onemacr;, a = 9.508(3) Å, b = 11.002(4) Å, c = 17.528(3) Å, alpha = 78.55(4), beta = 76.80(2), gamma = 87.51(2) degrees, V = 1750(1) Å(3), Z = 2, R = 0.0378; 3, monoclinic, C2/c, a = 18.553(4) Å, b = 9.110(2) Å, c = 16.323(3) Å, beta = 114.88(3) degrees, V = 2503(1) Å(3), Z = 4, R = 0.0457. Compound 1 shows bridging bidentate and chelating carboxylate ligands as well as bridging fluorine atoms. The zirconium atoms are seven coordinated and have an 18-electron configuration. X-ray studies of 3 reveal two structural components where the carboxylate ligands coordinate in a monodentate (major component) and a chelating manner (minor component).

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PubMed1996

First Mixed Fluoro-Chloro Group 4 Organometallics: Synthesis and Spectroscopic and Structural Characterization of [{(C(5)Me(5))ZrF(2)Cl}(4)], [{(C(5)Me(5))HfF(2)Cl}(4)], [(C(5)Me(5))(4)Zr(4)(&mgr;-F)(2)(&mgr;-F(2))(2)(&mgr;-Cl)(2)Cl(4)], [(C(5)Me(5))(4)Hf(4)(&mgr;-F)(2)(&mgr;-F(2))(2)(&mgr;-Cl)(2)Cl(4)], [(C(5)Me(4)Et)(2)ZrClF], and [(C(5)Me(5))(2)HfClF].

Tetrameric [{(C(5)Me(5))MF(3)}(4)] (M = Zr, Hf) react smoothly with Me(3)SiCl in CH(2)Cl(2) at room temperature to give [{(C(5)Me(5))ZrF(2)Cl}(4)] (1) and [{(C(5)Me(5))HfF(2)Cl}(4)] (2), respectively, in high yield. Treatment of [{(C(5)Me(5))MF(3)}(4)] (M = Zr, Hf) with Me(2)AlCl in toluene gives mixtures of 1 and [(C(5)Me(5))(4)Zr(4)(&mgr;-F)(2)(&mgr;-F(2))(2)(&mgr;-Cl)(2)Cl(4)] (3), and 2 and [(C(5)Me(5))(4)Hf(4)(&mgr;-F)(2)(&mgr;-F(2))(2)(&mgr;-Cl)(2)Cl(4)] (4), respectively, in an approximately 1:1 molar ratio. Metallocene type complexes [(C(5)Me(4)Et)(2)ZrCl(2)] and [(C(5)Me(5))(2)HfCl(2)] react with 1 equiv of Me(3)SnF to give [(C(5)Me(4)Et)(2)ZrClF] (5) and [(C(5)Me(5))(2)HfClF] (6), respectively. The complexes 1-6 were characterized by spectroscopic methods ((1)H and (19)F NMR and mass spectroscopy). The solid state structures of 1, 3, and 5 were determined by single-crystal X-ray diffraction analyses.

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