Roberta O. Day

Structure of Antimony tris-(O,O-Diethyl Phosphorodithioate), a Passivation Agent for Contaminant Metals in the Catalytic Cracking of Crude Petroleum

Abstract The coordination polyhedron of the antimony atom in antimony tris-(O,O-diethyl phosphorodithioate) is a distorted capped octahedron with a stereochemically active lone pair in the capping position and approximately on a molecular pseudo triad axis which passes through the antimony atom.

CYCLIC PENTAOXY SILICONATES1,2

Abstract Spirocyclic pentaoxy anionic silicates are synthesized and their molecular structures determined by X-ray diffraction. The K, 18-crown-6 salt of [(OCMe2CMe2O)2SiO-t-Bu] (1), formed from the reaction of the bis-pinacol spirosilicate and potassium t-butoxide, represents a new substance. Both the butylammonium salts, [(OCMe2CMe2O)2SiOR][n-BuNH3] R = OEt (2); R = OMe (3), have structures considerably displaced from a trigonal bipyramid toward a rectangular pyramid, 38.9% for 2 and 71.2% for 3, compared to 24.1% for 1. Hydrogen bonding is implicated in accounting for the greater structural displacement of 2 and 3. These pentaoxy derivatives represent the first members of this class that have been structurally characterized. Comparisons with related five-coordinated silicon and phosphorus compounds support their use as models in nucleophilic substitution reactions.

NOVEL CYCLIC PENTACOORDINATE AND PSEUDOPENTACOORDINATE LEAD COMPOUNDS

Abstract The new bicyclic lead(II) phosphinate [(t-Bu)2PO2]2Pb (1) was synthesized by the reaction of p-tolyllead triacetate with di-t-butylphosphinic acid and water. An X-ray study showed that it had a pseudo-trigonal bipyramidal geometry (p-TBP) with a stereochemically active lone pair of electrons occupying an equatorial site. Infrared data ruled out the possible presence of a Pb[sbnd]H bond. A series of new monocyclic Pb(IV) compounds, [Et4N][(MeC6H3S2)PbPh2X] where X = Br (2), CI (3), and F (4), was synthesized from the addition reaction of tetraethylammonium halide to 2,2-diphenyl-1,3,2-toluene dithiolato plumbole(IV), (MeC6H3S2)PbPh2 (5). An X-ray study of 3 revealed a monocyclic anionic TBP geometry which was compared with related dithiolato cyclic structures formed earlier by lighter elements of Group IVA. The lead(II) compound 1 crystallizes in the monoclinic space group C2/c with a = 15.594(4) A, b = 16.889(3) A, c = 12.642(2) A, β = 136.85(1)°, and Z = 4. The lead(IV) compound 3 crystallizes i...

2-Phospha-Allylic Systems

Abstract Phosphamethincyanines prepared in 1964 by Dimroth and Hoffmann were among the first compounds with two-coordinate phosphorus. They are special cases of 2-phospha-allylic cations. Simple representatives of this type become available from the reaction of imidoyl chlorides with tris(trimethylsily1)phosphane.

Oxygen- and Sulfur-Capped Organotin Clusters

Abstract The synthesis and structural features of the oxygen-capped cluster, [(n-BuSn(OH)O2P (OBut)2)3O] [O2P(OBut)2] (l), are compared to that of the analogous formulations containing framework sulfur atoms in place of oxygens, [(n-BuSn(S) (OH)OP(OBut)2)3S] [O2P(OBut)2]·2H2S·H2O (2) and [(n-BuSn)3(S)(O)(O2CPh)5] (3). Solution NMR, 119Sn and 31P, indicate that the solid state structures determined by X-ray analysis are retained in solution.

NEW RING SYSTEMS OF ELEMENTS OF MAIN GROUPS IV AND V

Abstract The synthesis of [PhSn(O)O2CC6H11]6 represents the first example of tin(IV) in a drum-shaped molecule. The formation of the dimeric composition, [(MeSn(O)O2CC6H11)2(MeSn(O2CC6H11)3]2, appears to be an intermediate hydrolysis product on the way to the drum composition. The X-ray structure reveals an “unfolded” drum array. The distannoxane unit which is represented as the sides of the drum is found in additional new dimeric compositions, [(SCH2CH2O)2SnCl]2[H][Et4N], [((CN)2C2S2)2SnOH]2, and [BuSnCl2(OH) · H2O]2. These all have six-coordinated tin atoms which contrasts to the dimeric aryl distannoxanes recently isolated, [Ph2(Cl)SnOSnPh2(X)]2, X = OH, Cl, containing five-coordinated tin. Also isolated are the new ring containing, five-coordinated tin derivatives, [(SCH2CH2S)2Sn]2[SCH2CH2S][Et3NH]2 and [(SC(CN)C(CN)S)2SnMe][Et4N]. The former has two trigonal bipyramidal tin atoms while the latter composition has a square pyramidal geometry. Related ring systems of new five-coordinated derivatives of ...

THREE-, FOUR-, AND FIVE-COORDINATE CYCLIC PHOSPHITES, PHOSPHONATES, AND PHOSPHONIUM SALTS CONTAINING SULFURYL GROUP

Abstract Reaction of the sulfuryl diphenol O2S[(t-BU)MeC6H2OH]2 (10) with phosphorus trihalides in the presence of amines yielded the phosphites O2S[(t-Bu)MeC6H2O]2PR where R = Cl for 1 and R = Br for 2. Treatment of 1 with 2,6-dimethylphenol in a halide displacement reaction gave 3 (R = OXyl). In a similar diol reaction with O2S[Me2C6H2OH]2 (11), the hydrogenphosphonate O2S[Me2C6H2O]2P(O)H (5) formed. A related hydrogenphosphonate O2S[(t-Bu)MeC6H2O]2P(O)H (4) was obtained by hydrolysis of either 1 or 2. The phosphonium bromide salt O2S[(t-BU)MeC6H2O]2PPhBr+Br− (7) formed from the bromination of the phenylphosphonite derivative O2S[(t-Bu)MeC6H2O]2PPh (9), the hydrolysis of which yielded the phosphonate O2S[(t-Bu)MeC6H2O]2P(O)Ph (6). A related phosphonium bromide O2S[(t-Bu)MeC6H2O]2PBr2 +Br− (8) was prepared by the reaction of the diphenol 10 with PBr3 in the presence of N-bromodiisopropylamine. All of the cyclic phosphorus derivatives 1–8 were characterized by x-ray studies and NMR measurements. All of the compounds lack donor-acceptor interaction that is potentially available via the oxygen atom of the sulfuryl group present as part of the ring system except for 4. For 4, the structure is pentacoordinated with a displacement from a tetrahedral geometry toward a trigonal bipyramid, The ring conformation is a syn twist-boat whereas the others lacking donor coordination reside in an anti chair-like ring arrangement. Solution 31P NMR chemical shifts are in appropriate ranges indicating retention of the coordination geometry that was found in the solid state. Weak P-Br bond strength is suggested to account for formation of the phosphonium bromides 7 and 8 which contrasts with the hexacoordinate structure obtained previously for an analogous chlorophosphorane. Comparisons with similar formulations of cyclic phosphites and phosphates having ring sulfur atoms show that there is a preponderance of donor-acceptor interactions involving sulfur compared to that experienced with the sulfuryl group.

SYNTHESIS AND MOLECULAR STRUCTURES OF FLUOROPHOSPHORANES, R3PF2, ISOELECTRONIC WITH ANIONIC FLUOROSILICATES

Abstract The new difluorophosphoranes Ph(o-Tol)2PF2 (1), Mes3PF2 (2), Ph(I-Np)2PF2 (3), (o-Tol)3PF2, (p-Tol3PF2, Ph(t-Bu)2PF2, and (Ph2PF2CH2 containing bulky substituents were prepared by the fluorination reaction of precursor organophosphines with dimethylaminosulfur trifluoride. They were characterized by 1H, 31P, and 19F NMR spectra. The molecular structures of 1–3 revealed trigonal bipyramidal geometries. Comparison of the structural data with that of isoelectronic anionic fluorosilicates along with the NMR data suggests the operation of a steric effect that increases bond lengths in the difluorophosphoranes 1–3 and in related anionic silicates. The data are discussed relative to enhanced reactivity observed for anionic silicates. 1 crystallizes in the monoclinic space group C2/c with a = 11.819(3) A, b = 10.163(2) A, c = 13.992(3) A, β = 99.14(2)°, and Z = 4.2 crystallizes in the monoclinic space group C2/c with a = 10.531(2) A, b = 12.667(2) A, c = 18.110(4) A, β = 104.21(2)°, and Z = 4. 3 crystall...

A New Class of Silatranes

A series of silatranes containing all six-membered rings N[CH2(Me2C6H2)O]3SiR was prepared using tris(2-hydroxy-4,6-dimethylbenzyl)amine as the encapsulating agent. VT 1H NMR spectra reflected fluxional behavior for all of these chiral molecules. The activation energies for enantiomeric conversion of the propeller-like silatranes correlated with the extent of structural rigidity associated with the ring system. The degree of nitrogen donor interaction depends primarily on electronegativity effects induced at silicon by the exocyclic ligand.

The formation and properties of mono-cyclopentadienyltitanium dichloride complexes containing trimethylphosphine and isonitrile ligands: molecular structure of (η5-C5H5)TiCl2(PMe3)2

Reduction of CpTiCl 3 in THF solution by magnesium in the presence of either excess trimethylphosphine or 2,6-dimethylphenylisonitrile at ca. −30°C produces the titanium(III) complexes CpTiCl 2 (PMe 3 ) 2 and CpTiCl 2 (CNC 6 H 3 Me 2 ) 2 , respectively, in good yields. The X-ray structure of CpTiCl 2 (PMe 3 ) 2 is reported.