Synthesis, Structural Characterization, and Reactions of Cyclic Organohydroborate Half-Zirconocene Compounds (original) (raw)
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Australian Journal of Chemistry, 1986
Reaction of PtCl2(en) (en = ethane-1,2-diamine) with thallous pentafluorobenzoate in hot pyridine ( py ) or 4-methylpyridine ( mepy ) yields the [N,N′- bis (2,3,5,6-tetrafluorophenyl)ethane-1,2-diaminato(2-)]platinum(II) complexes, Pt[N(p-HC6F4)CH2]2( py )2 (1a) and Pt[N(p- HC6F4)CH2]2( mepy )2 (1b). The route to (1a) is considered to involve formation of [Pt(en)( py )2](O2CC6F5)2 (2), decarboxylation of (2) into Pt(NHCH2)2( py )2 (1c) and pentafluorobenzene, and nucleophilic attack of (1c) on C6F5H. Complex (1a) has also been prepared by decarboxylation of (2), reaction of PtI2(en) and TlO2CC6F5, and reaction of PtCl2(en), C6F5H, and TlO2CC6F4H-p in boiling pyridine. From reaction of PtCl2(en), TlO2CC6F4H-p, and the appropriate polyfluorobenzene (RF) in boiling pyridine or 4-methylpyridine, the organoamidoplatinum compounds Pt(NRCH2)2L2(R = C6F5, p-MeC6F4, p-ClC6F4, p-BrC6F4, p-IC6F4, 2,3,5-F3C6H2, or p-C6F5C6F4, L = py and R = C6F5, L = mepy ) have been prepared. Analogous reactio...
Organometallics, 1997
Alkylation of [Zr(CpSi 2 Cp)Cl 2 ] (CpSi 2 Cp) (η 5-C 5 H 3) 2 [Si(CH 3) 2 ] 2 with 1 equiv of RMgCl in THF at 10°C gave the monoalkylated complexes [Zr(CpSi 2 Cp)ClR] (R) Et, n-Pr, i-Pr) in 80% yield, the isopropyl complex isomerizing to the n-propyl derivative above 10°C. Addition of a second equivalent or an excess amount of the akylating agent resulted in the formation of the dialkyl compounds [Zr(CpSi 2 Cp)R 2 ] (R) Et, n-Pr). Hydrolysis of [Zr(CpSi 2 Cp)ClR] led to the µ-oxo dinuclear complex [{Zr(CpSi 2 Cp)Cl} 2 (µ-O)]. Thermal decomposition of THF solutions of [Zr(CpSi 2 Cp)ClR] takes place with the evolution of an equimolar amount of alkane and alkene and the formation of [Zr(CpSi 2 Cp)Cl 2 ] and an unidentified residue. Formation of [Zr(CpSi 2 Cp)Et 2 ] is always accompanied by decomposition with the evolution of ethane to give [{Zr(CpSi 2 Cp)Et} 2 (µ-CH 2 dCH 2)] in 70% yield. A similar behavior was observed for [Zr(CpSi 2 Cp)(n-Pr) 2 ]. All of the compounds were characterized by elemental analysis and NMR spectroscopy, and the molecular structures of [Zr(CpSi 2 Cp)ClEt] and [{Zr(CpSi 2 Cp)-Et} 2 (µ-CH 2 dCH 2)] were studied by X-ray diffraction methods. Density functional calculations on the model compound [{ZrCp 2 Me} 2 (µ-CH 2 dCH 2)] satisfactorily reproduce d CC) 1.482, d1 Zr-C) 2.327 Å, and d2 Zr-C) 2.506 Å, the geometry found experimentally.
Organometallics, 1987
(1) has been prepared and shown to exist in several isomeric forms by IH and lg5Pt NMR spectroscopy. Complex 1 is a synthetically useful form of soluble PtC12 and also catalyzes the hydrosilylation of styrene with Et3SiH. This latter reaction has been carried out with a variety of known complexes of platinum(II), and the results have been compared with those found for some trichlorostannate complexes of platinum. One isomer of 1 has been crystallized and its structure determined by X-ray diffraction. Crystal data for this isomer: space group PZ1/c, a = 13.805 (7) A, b = 10.235 (2) A, c = 10.985 (7) A, j 3 = 106.51 (4)'; Z = 4; V = 1489.1 A3.
Journal of …, 2008
The ansa-bis(cyclopentadiene) compounds, Me 2 Si(C 5 HPh 4 )(C 5 H 4 R) (R = H (2); Bu t (3)), have been prepared by the reaction of C 5 HPh 4 (SiMe 2 Cl) (1) with Na(C 5 H 5 ) or Li(C 5 H 4 Bu t ), respectively, and transformed to the di-lithium derivatives, Li 2 {Me 2 -Si(C 5 Ph 4 )(C 5 H 3 R)} (R = H (4); Bu t (5)), by the action of n-butyllithium. The ansa-zirconocene complexes, [Zr{Me 2 Si(g 5 -C 5 Ph 4 )(g 5 -C 5 H 3 R)}Cl 2 ] (R = H (6); Bu t (7)), were synthesized from the reaction of ZrCl 4 with 4 or 5, respectively. Compounds 6 and 7 have been tested in the polymerization of ethylene and compared with their methyl-substituted analogues, [Zr{Me 2 Si(g 5 -C 5 Me 4 )(g 5 -C 5 H 3 R)}Cl 2 ] (R = H (8); Bu t (9)). Whilst 8 and 9 are catalytically active, the tetraphenyl-substituted complexes 6 and 7 proved to be inactive in the polymerization of ethylene. This phenomenon has been explained by DFT calculations based on the reaction intermediates in the polymerization processes involving 6 and 7, which showed that the extraction of a methyl group from the zirconocene complex to form the cationic active specie is endothermic and therefore unfavourable.
Organometallics, 1988
T h e reactions of silanes and silyl halides with the 16-electron alkoxyiridium complexes trans-ROIr-(CO)[P(p-tol),], (R = Me or Ph; p-to1 = p-tolyl) are reported. The silanes add oxidatively to the alkoxyiridium complex; the resulting complex undergoes reductive elimination of an alkoxysilane with ultimate formation of H,Ir(CO) (SiR,) [P(p-tol),lz. Reactions of silyl halides with the alkoxy complex results in formation of silicon-oxygen bonds. The dihydride HzIr(CO)(SiMe2Ph) [P(p-tol),],, which is an active hydrogenation-catalyst, was subjected to structural analysis. I t crystallizes in the centrosymmetric triclinic space group P1 with a = 10.692 (1) A, b = 11.199 (2) A, c = 20.557 (4) A, a = 75.991 (14)', @ = 84.505 (14)', y = 77.503 (ll)', V = 2329 (1) A3, and 2 = 2. Diffraction data (Mo K a , 28 = 4.5-45.0') were collected with a Syntex P21 automated diffractometer; the structure was solved and refined to RF = 4.9% for all 6119 reflections (RF = 3.6% for those 5094 data with IF, I > 6u(~F,,~)). The non-hydride ligands occupy expanded sites in an octahedral iridium(II1) complex with Ir-P(l) = Ir-P(2) = 2.366 (2) A, Ir-Si = 2.414 (2) A, and Ir-CO = 1.900 (8) A. T h e SiMezPh ligand is trans to a P(p-tol), ligand (P(1)-Ir-Si = 146.39 (7)'). T h e hydride ligands were located and refined; their positions are of limited accuracy, but they lie in mutually cis sites, trans t o a P(p-tol), ligand (P(2)-1r-H(1) = 169.2 (2 1) O) and to the CO ligand (C-(l)-Ir-H(2) = 169.4 (22)'). A number of transition-metal complexes have been used as catalysts in t h e commercially important process of 0-silylation, which involves silicon-oxygen bond format i~n .~ I n this paper we report a stoichiometric Si-0 bond formation by reductive elimination from the intermediate formed by addition of a silane or a silyl halide to trans-R O I r (C 0) [P(p-tol),],. Addition of group 14 hydrides t o square-planar iridium complexes has been extensively ~t u d i e d .~ trans-Ir(CO)(PPh3)zC1 + HMR3 I~(H) (M R~) (C O) (P P~~) Z C~ M = Si, Ge, Sn; R = alkyl, aryl U n d e r forcing conditions t h e silyl chloride (M = Si in above equation) could be eliminated and a second molecule of silane added.4 T h e s e reactions depended strongly o n t h e steric a n d electronic nature of t h e substituents on t h e ~i l a n e .~ W e have been examining various reactions of alkoxy5 (1) University at Buffalo. (2) College at Fredonia.
Australian Journal of Chemistry, 1988
The complexes Pt[N(p-HC6F4)CH2CH2NMe2]X(L) (L = py , X = Cl or Br; L = 2- methylpyridine or 4-methylpyridine, X = Cl ) have been prepared by decarboxylation reactions between PtX2( dmen ) ( dmen = N,N- dimethylethane - 1,2-diamine) and thallous pentafluorobenzoate in the appropriate hot pyridine. Other organoamidoplatinum (II) complexes, Pt[N(R)CH2CH2NMe2] X( py ) (R = p-HC6F4, X = I; R = C6F5, X = Cl , Br or I; R = p-MeC6F4, X = Cl ; R = p-ClC6F4 or p-BrC6F4, X = I) and Pt[N(R)CH2CH2NMe2] Cl ( dmpy ) (R = p-HC6F4; dmpy = 2,5-dimethylpyridine), have been prepared by analogous decarboxylations between PtX2( dmen ), thallous 2,3,5,6- tetrafluorobenzoate, and the corresponding polyfluorobenzene, RF. The mixed halogen complex Pt[N(C6F5)CH2CH2NMe2]I0.63Cl0.37( py ) has been prepared similarly and the crystal structure determined. This shows square-planar stereochemistry with the halogen and pyridine trans to NC6F5 and NMe2 respectively. Comparison of spectroscopic data suggests the other...