Showing papers by "Arnold L. Rheingold published in 1991"

Volatile Barium Beta-Diketonate Polyether Adducts. Synthesis, Characterization and Metalorganic Chemical Vapor Deposition

Abstract: : The 2,5,8,11,14-pentaoxaheptadecane (tetraglyme) adducts of barium complexes of 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (H(hfacac(), 1,1,1,- trifluoro-2,4-pentanedione (Htfacac) and 2,2,6,6-tetramethyl-3,5-heptanedione (H(thd)) have been prepared and characterized by X-ray crystallography, H and C nmr spectroscopies, melting and sublimation points, and elemental analysis. The thermal stability of the complexes is related to their solid state structure in which the coordination number around the barium atom is nine with a monocapped, twisted square prism structure. Metalorganic chemical vapor deposition experiments were performed using the 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate and 1,1,1-trifluoro-2,4-pentanedionato complex; the 2,2,6,6-tetramethyl-3,5- heptanedionate complex dissociated prior to sublimation. The as-deposited barium fluoride films were characterized by scanning electron microscopy and energy dispersive x-ray spectroscopy.

Solid state and solution structural investigation of homoleptic tin(IV) alkoxide compounds. Part I. Sn(O—t-Bu)4 and [Sn(O—i-Pr)4•HO—i-Pr]2

Abstract: The crystal and molecular structures of Sn(O—t-Bu)4• and [Sn(O—i-Pr)4•HO—i-Pr]2 have been determined by single-crystal X-ray diffraction. Sn(O—t-Bu)4 crystallizes in the monoclinic crystal system with space group C2/c, where a = 17.382(6) A, b = 8.742(2) A, c = 15.518(5) A, β = 116.44(1)°, Z = 4, and R = 2.5%. Sn(O—t-Bu)4 is monomeric in the solid state, with a distorted tetrahedral tin coordination environment. [Sn(O—i-Pr)4•HO—i-Pr]2 crystallizes in the monoclinic crystal system with space group P21/n, where a = 11.808(3) A, b = 14.356(3) A, c = 12.380(2) A, β = 95.27(2)°, Z = 2, and R = 4.9%. [Sn(O—i-Pr)4•HO—i-Pr]2 exhibits an edge-shared, bi-octahedral structure in the solid state that is distorted due to the presence of asymmetric hydrogen bonding between axially coordinated alcohol ligands and an isopropoxide ligand.13C NMR and IR spectroscopic data have been recorded for Sn(O—t-Bu)4 and Sn(O—t-Bu-d9)4 to establish criteria for unambiguous identification of solution structures of tin(IV) alkoxides. I...

Poly(pyrazolyl)borate complexes of tin(II). Crystal and molecular structures of [H2B(pz)2]SnCl and [B(pz)4]2Sn (pz = pyrazolyl ring)

Abstract: The complexes [H n B(pz) 4−n ] m SnCl 2−m (n=0-2; m=1, 2; pz=pyrazolyl ring) have been prepared by the reaction of SnCl 2 and the ligand salts in the appropriate stoichiometries. The complexes are air stable in the solid phase with solution stability increasing with the number of poly(pyrazolyl) borate ligands and the number of pyrazolyl rings present in the ligand. The structure of [H 2 B(pz) 2 ]SnCl) has been determined by X-ray crystallography: monoclinic, P2 1 /n

Structure and Bonding in Cationic Cyclopentadienyliron Complexes Containing Thio-, Seleno-, and Telluroethers as Ligands'

Abstract: An extended Huckel MO study based on X-ray structure determinations of [C 5 H 5 Fe(CO) 2 (ER) 2 )]BF 4 complexes (I: E=S,R=CH 3 , C 6 H 5 ; E=Se, Te, R=CH 3 ) and their chemistry confirms and rationalizes the inertness and stability of the Fe−E bond in these cations in the order E=Te>>Se>S>O on the basis of electronegativity, orbital diffuseness, and size considerations. No important π-bonding effect is found, and a comment on the photochemical replacement of CO is made

Reactivity of palladium(II) complexes with bidentate bis(phosphine) ligands toward the octahydrotriborate(1-) anion and dependence of the reaction upon halide arrangement : molecular structure of the trans-(bis(diphenylphosphino)hexane)palladium(II) dichloride dimer

Abstract: The reactivity of the palladium (II) bis (phosphine) complexes, (Ph 2 P(CH 2 ) n PPh 2 )PdCl 2 (n=1-6) toward the octahydrotriborate (1−) anion, [B 3 H 8 ] − , has been investigated. For n=1-4, the metallaborane (Ph 2 P(CH 2 ) n PPh 2 ) Pd(B 3 H 7 ) is produced, although the yield depends upon the organic chain length of the phosphino ligand and is maximized when n=2. Our observation that no reaction occurs between the [B 3 H 8 ] − anion and (bis(diphenylphosphino) pentane)- or (bis(diphenylphosphino) hexane)-palladium (II) dichloride leads us to examine the structure of these starting materials

Polydentate ligands containing phosphorus. 13. Synthesis and molecular structure of (tri-n-butylphosphine)[tris(diphenylthiophosphinoyl)methanido]silver(I), (n-Bu)3PAg{[(S)PPh2]3C}

Abstract: The synthesis, NMR spectra, and molecular structure are described for (tri-n-butylphosphine) [tris(diphenylthiophosphinoyl)-methanido] silver (I). The compound crystallizes in monoclinic space group P2 1 /c

Important factors in oxygen atom transfer to metal carbonyls. Rate of carbonyl substitution of chromium hexacarbonyl and iron pentacarbonyl in the presence of para-methoxyphenol chalcogenide oxide (p-CH3OC6H4)2EO (E = selenium, tellurium) and of triphenyl metal oxide (C6H5)3EO (E = arsenic, antimony). Syntheses and x-ray structure of Cr(CO)5E(p-CH3OC6H4)2

Abstract: An attempt is made to obtain information on the various factors that contribute to the overall O atom transfer rates of reactions of metal carbonyls of the type M-CO+E-O→M+CO 2 E. The metal carbonyls used were Cr(CO) 6 and Fe(CO) 5 , and the O atom transfer reagents were (p-CH 3 OC 6 H 4 ) 2 EO (E=Se, Te), (C 6 H 5 ) 3 EO (E=P, As, Sb), and (C 6 H 5 ) 2 SO. There was no reaction with either (C 6 H 5 ) 3 PO or (C 6 H 5 ) 2 SO, under the experimental conditions used. The reagents that did react transfer their O atoms at the relative rates of TeO>SeO>SbO>AsO. These results, along with previously reported data, are discussed in terms of the various important factors believed to contribute to the energetics of these overall reactions

Competition between triborane as a ligand and a hydride donor at platinum centres containing chelating phosphines: molecular structures of [{Ph2P(CH2)2PPh2}PtB3H7], [{Ph2P(CH2)4PPh2}PtB3H7] and [Pt2H3{(Ph2PC5H4)2Fe}2]Cl

Abstract: The reaction of [PtCl2(L–L)][L–L = Ph2P(CH2)nPPh2, n= 2, 3 or 4; or Fe(η5-C5H4PPh2)2] with the octahydrotriborate(1–) anion, [B3H8]–, leads to both [(L–L)PtB3H7] in which the borane unit acts as a pseudo-bidentate ligand and [Pt2H3(L–L)2]Cl which results from the borane anion functioning as a hydride donor. For each of the complexes containing a bis(diphenylphosphino) alkane ligand the major product is [{Ph2P(CH2)nPPh2}PtB3H7], whereas for the reaction of [B3H8]– with [Fe(η5-C5H4PPh2)2], [Pt2H3{(Ph2PC5H4)2Fe}2]Cl is the predominant species formed. Three products have been structurally characterised: [{Ph2P(CH2)2PPh2}PtB3H7]1, space group P21/c, a= 16.049(4), b= 15.395(4), c= 21.075(5)A, β= 90.53(2)°, Z= 8, R= 0.039; [{Ph2P(CH2)4PPh2}PtB3H7]3, space group P21, a= 8.8826(18), b= 17.7329(32), c= 9.5520(17)A, β= 114.115(15)°, Z= 2, R= 0.032; [Pt2H3{(Ph2PC5H4)2Fe}2]Cl·3CH2Cl26, space group p21/c, a= 12.862(2), b= 38.732(6), c= 14.271(2)A, β= 99.027(15)°, Z= 4, R= 0.067. The structure of the cation of 6 resembles that of [Pt2(µ-H)2H{Ph2P(CH2)2PPh2}2]+ rather than that of [Pt2(µ-H)H2{But2P(CH2)3PBut2}2]+ thereby indicating that it is the steric bulk of the phosphorus substituents rather than the P–Pt–P bite angle that controls the geometry of the {Pt2P4} framework and thus the hydride locations. Fenske–Hall molecular orbital calculations have been used to probe the mode of bonding of the hydride ligands to the diplatinum centre.

Cycloaddition reactions across the Ti O bond of (tmtaa)Ti O (tmtaa = dianion of 7,16-dihydro-6,8,15,17-tetramethyldibenzo[b, i][1,4,8,11]tetraazacyclotetradecine)

Abstract: The complex (tmtaa)TiO undergoes [2 + 2] cycloaddition of the TiO bond across the CO bond of ketones and [(C5Me5)Re(CO)2(NO)]+, the SO bonds of SO2 and SO3, the CS bond of CS2, and ring opens epoxides and cyclic anhydrides to give metallacycles.

Formation and structure of a quadruply-iodo-bridged complex of dimolybdenum(III,IV), [(Cp*Mo)2(µ-l)4]l3(Cp*=η5-C5Me5) and its reversible oxidation and reduction

Abstract: The mixed-valence quadruply-iodo-bridged [(Cp*Mo)2(µ-l)4]l3 has been crystallographically characterized; its cyclic voltammogram shows reversible oxidation and reduction processes and suggests that the [(Cp*Mo)2(µ-l)4]n+(n= 0,1,2) series of complexes is isostructural.