Ph Bond Research Articles

The synthesis and X-ray structural characterization of bis[(2S,3S)-2,3-bis(diphenylphosphino)butane]rhodium(I) chloride and its reactivity towards small gas molecules

The [Formula: see text] cation, where chiraphos is 2,3-bis(diphenylphosphino)butane, has been synthesized and fully characterized by spectroscopy and single crystal data on the chloride salt (1). Crystals are monoclinic, a = 23.106(3), b = 12.4987(8), c = 21.455(3) Å, β = 128.539(5)°, Z = 4, space group C2. The structure was solved by conventional heavy atom methods and was refined by full-matrix least-squares procedures to R = 0.046 and Rw = 0.032 for 4509 reflections with I > σ(I). The coordination about Rh is square planar distorted toward tetrahedral within the five-membered chelate rings, similar to that in [Formula: see text], where dpe is 1,2-bis(diphenylphosphino)ethane, but the distortion toward tetrahedral is significantly greater in 1; the methyl substituents further restrict rotational freedom about the P—Ph bonds, which leads to some blocking of the axial ligand sites by the four H atoms of the chelate-ring carbon atoms. In solution, 1 is unreactive towards O2, CO, and H2, but oxidatively adds HX (X = Cl, Br) to give trans-[Formula: see text] species.

Oligophosphaalkane: X. Disekundäre methylenbisphosphane HPRCH 2PRH; bausteine für cluster mit (μ 2-PR) 2CH 2-, μ 2-PRCH 3- und μ 3-PR-brücken

Methylene-bridged disecondary phosphanes HRPCH 2PRH (R = i-Pr, CH 2Ph, Me, t-Bu; Ia–Id) react with excess Fe 2(CO) 9 to give the cluster compounds Fe 3(CO) 9(μ 2-PRCH 2-PRH)(μ-H) (IIIa–IIId) and Fe 3(CO) 9(μ-PR)(μ 2-PRCH 3)(μ-H) (Va–Vd) through cleavage of the PH bond and the PCP skeleton. Pyrolysis of Va, Vb and Vd affords the unsymmetrically substituted bis-μ 3-phosphinidene bridged clusters Fe 3(CO) 9(μ 3-PR)(μ 3-PMe) (VIa, VIb and VId). If Ia or Id is treated with Fe 2(CO) 9 in a 1 2 molar ratio at high temperature, the formation of the binuclear complexes Fe 2(CO) 6(RPCH 2PR) (VIIa, VIId) is accompanied by fragmentation of their PCP backbones. As a result, Fe 2(CO) 6(μ 2-P(i-Pr)H)(μ 2-P(i-Pr)CH 3) (VIII) or VId and Fe 3(CO) 7[(μ 2-P(t-Bu)) 2CH 2](μ 2-P(t-Bu)Me)(μ-H) (IX) with the unusual (μ 2-PR) 2-CH 2 bridge for the Fe 3-triangle are formed. X-Ray structural analysis of Va (triclinic, space group P 1 ) shows an open Fe 3 unit (Fe(1)-Fe(2) 2.774(1), Fe(1)-Fe(3), 2.807(1), Fe(2)-Fe(3) 3.476(1) Å) stabilised by the μ 3-P(i-Pr) and μ 2-P(i-Pr)Me bridges. In cluster IX (monoclinic, space group P2 1/ c), the triangle of iron atoms (Fe(1)-Fe(2) 2.831(1), Fe(1)-Fe(3) 2.806(1), Fe(2)-Fe(3) 2.557(1) Å) is capped by the bifunctional phosphido group (μ 2-P-(t-Bu)) 2CH 2. In addition, the Fe(2)-Fe(3) edge is spanned by the μ 2-P(t-Bu)Me and μ-H species.

Carbon‐13 NMR Spin‐Lattice Relaxation and Molecular Motion in 2‐Phenyl‐1,3,2‐dioxarsolane and its 4‐Methyl and 4,5‐Dimethyl Derivatives

Abstract13C NMR spin‐lattice relaxation times (T1) have been measured as a function of temperature for three 2‐phenyl‐1,3,2‐dioxarsolanes. The T1 data have been interpreted in terms of isotropic overall molecular reorientation, internal rotation about the AsPh bond and internal methyl rotation. Information on the relative order of magnitude of the overall and internal reorientations has been obtained. The internal rotation of the phenyl ring is thus 2—4 times faster than the overall molecular tumbling. Further, the internal rotation of the arsolane ring appears to be comparable to, or slightly faster than, the phenyl ring rotation. The association process which is believed to take place in the unsubstituted parent compound is reflected in its very high activation energy for overall reorientation (39 kJ mol−1 compared with 24‐25 kJ mol−1 for the methyl derivatives). The rotation of the methyl groups appears to be considerably more hindered in the cis isomer of 2‐phenyl‐4,5‐dimethyl‐1,3,2‐dioxarsolane than in the trans isomer and, in particular, the mono‐4‐methyl compound.

Gekkopelte einschiebung von “NC” in die metall-carbenkohlenstoff-bindung und von “C(R′)Ph” in die RCN-bindung bei der reaktion von (CO) 5M[C(R′)Ph] mit RCN

The pentacarbonyl[methoxy(phenyl)carbene]complexes (CO) 5M[C(OMe)Ph][M = Cr (Ia), Mo (Ib), W (Ic) react with [(Ph 3P) 2N][NCBH 3] to give the new nitrile complexes [(Ph 3P) 2N] + {(CO) 5M[NCC(OMe)(Ph)BH) 3]} −. The reaction of Ic with NCSiMe 3 yields (CO) 5W[NCC(OMe)(Ph)SiMe 3]; however, in the presence of silica gel (CO) 5W[NCC(OMe)(Ph)H] is obtained. From the reaction of pentacarbonyl(diphenylcarbene)tungsten, (CO) 5W[CPh 2], with NCSnBu n 3 in diethyl ether, (CO) 5W[NCCHPh 2] was isolated. Formally, the new nitrile complexes correspond to the products of a coupled insertion: (a) of NC from RCN into the MC(R′)Ph bond of (CO) 5M[C(R′)Ph] and (b) of C(R′)Ph into the CR bond of RCN. For RSiMe 3 and SnBu n 3, subsequent hydrolysis of the initially formed complexes affords the R/H substitution products.

CRYSTAL STRUCTURE OF [Et4N]2[Fe4S4(2,4,6-TRIMETHYLBENZENETHIOLATO)4

Abstract The crystal structure of [Et4N]2[Fe4S4(2,4,6-trimethylbenzenethiolato)4] was determined by X-ray diffraction. The complex crystallizes in orthorhombic space group (Pcnb). The Fe4S42+ core of the anion approaches C2 symmetry. The complex has relatively long Fe–S(Ph) bond lengths and small Fe–S–C angles. The results suggest the prevention of π-overlap between Fe(d)-SPh(p) orbitals by the steric hindrance of two methyl groups at o-positions of phenyl group.

Syntheses, molecular structures and electrochemical behavior of two isomeric Ru(PhNpy) 2(PPh 3) 2 complexes

The title compounds, isomers of Ru(PhNpy) 2(PPh 3) 2 (PhNpy = the anion of 2-(N-anilino)-pyridine), having C 1 and C 2 symmetry, were prepared by reacting RuCl 2(PPh 3) 3 with LiPhNpy in toluene. The crystal and molecular structures of these compounds have been determined from three-dimensional X-ray study. Both compounds crystallize in the monoclinic space group P2 1/c with the following unit cell dimensions: C 1-isomer: a = 13.852(3), b = 18.872(3), c = 18.206(3), β = 84.32(5), V = 4736(2) and Z = 4. C 2-isomer: a = 11.166(9), b = 20.404(8), c = 20.716(16), β = 97.14(7), V = 4683(10) and Z = 4. The structures were refined to R = 0.053 (R w = 0.083) for the C 1-isomer and R = 0.055 (R w = 0.063) for the C 2-isomer. In the C 1-isomer, the coordinating atoms N-py, N-Ph and PPH 3 are all in cis-arrangement. In the C 2-isomer, the py-rings are trans to each other. The complexes are six-coordinate with four-membered chelate rings. The NRuN angle in the chelate rings is ca. 62° in each case. The RuP bond lengths lie in the range 2.286(3)–2.337(1) Å. The average RuN(py), and RuN(Ph) bond lengths are 2.083 Å and 2.171 Å, respectively. Dichloromethane solutions of the C 1 and C 2 isomers display two quasireversible oxidation waves at 0.480, 1.175 V and 0.290, 1.040 V, respectively. The responses have one-electron stoichiometry and are assignable to Ru III/Ru II and Ru IV/Ru III couples.

MNDO calculations for some allotropes, hydrides, and oxides of phosphorus

Molecular orbital calculations by the MNDO method are reported for some allotropes, hydrides, and oxides of phosphorus. The aim of the study is to test further the ability of MNDO to reproduce the energetics of PP, PH, and PO bonds, and to apply MNDO to interesting problems in the chemistry of such systems. Different isomers of P4, P6, and P8 are considered, as well as ions of P3, P5, and P7. The method is found to overestimate strain energy in three-membered rings, and to underestimate the strength of three-electron PP bonds. The strength of PO π bonds apparently also is overestimated. Possible isomers of P2O2 and P2O3 are discussed.

Electronic Absorption Spectra and Geometry of Molecular Ions Generated from Stilbene and Related Compounds. III. Radical Ions of (Z)-Stilbene and Its α,β-Dialkyl Derivatives

Abstract The radical ions of (Z)-stilbene and its α,β-dialkyl derivatives were produced by γ-ray irradiation of the parent compounds in frozen matrices at 77 K, and their geometries were investigated by electronic absorption spectroscopy. While the relaxed geometries of the radical ions of (Z)-stilbene are probably similar to that of the neutral molecule, those of the radical ions of the α,β-dialkyl derivatives are appreciably different from those of the neutral molecules: The torsion angle of the central ethylenic bond is distinctly larger and that of each C–Ph bond is probably smaller in the radical ions than in the neutral molecules. On illumination the radical ions of (Z)-stilbene isomerize to the E isomers, but those of the α,β-dialkyl derivatives do not. A mechanism of the photoisomerization is proposed, and an interpretation of the difference in the photochemical behavior between the unsubstituted stilbene radical ions and the α,β-dialkyl derivatives is given.

ON SOME CHEMICAL PROPERTIES OF 1-PHENYLPHOSPHINDOLE

Abstract The title compound 5 can be easily synthesized by combination of two published procedures. It undergoes quantitative lithium cleavage of the exocyclic P—Ph bond, and phosphorus substituent exchange by reaction with t-butyllithium. The phosphindolyl anion displays a 31P NMR signal at higher field than the corresponding phospholyl anion, and is also more reactive towards ethanol. This indicates a higher basicity and a lower aromaticity of the phosphindolyl anion vs. the phospholyl anion. Bromo derivatives in α-as well as β-position to phosphorus were also prepared. Reaction of 5 with Mn2(CO)10 afforded a π-phosphindolyl complex whereas reaction of t-butylphosphindole with Mn2(CO)10 only gave a [sgrave]-complex. Phosphindolyl anion with BrMn(CO)5 gave μ-phosphido complexes but did not give any ferrocene analogue by reaction with FeCl2, indicating a lowering of the stability of the phosphametallocenes upon benzoannelation.

ChemInform Abstract: CONVERSION OF ALLYLPHOSPHINE TO NOVEL DISPHOSPHINES: SYNTHESIS AND CHARACTERIZATION OF CH2:CHCH2P(H)(CH2)3PH2 AND P((CH2)3)3P

AbstractDie Photoreaktion von Allylphosphin (I) in der Gasphase liefert das P‐Allyl‐propylendiphosphin (II), die Radikalreaktion von (I) mit Azoisobuttersäuredinitril (III) neben PH3 das 1,5‐Diphosphabicyclo[3.3.3]undecan (IV).

CONVERSION OF ALLYLPHOSPHINE TO NOVEL DIPHOSPHINES: SYNTHESIS AND CHARACTERIZATION OF CH2=CHCH2P(H)(CH2)3PH2AND P[(CH2)3]3P1

Abstract Irradiation (λ = 300–600 nm) of gaseous CH2=CHCH2PH2 in a hot-cold reactor yields the new diphosphine, CH2=CHCH2P(H)(CH2)3PH2(I). I results from the intermolecular head-to-tail addition of phosphine PH bonds to the C=C bonds of CH2=CHCH2PH2, in an anti-Markovnikov process. The AIBN-initiated radical reaction of CH2=CHCH2PH2 in benzene yields PH3 and the novel bicyclic diphosphine, P[(CH2)3]3P(II). Characterization of I and II, based on 31P, 1H, and 13C NMR and mass spectral data, is described.

Carbon‐13 NMR spin‐lattice relaxation in dithiarsolanes. Correlation between molecular motions and structural properties

Abstract13C NMR spin‐lattice relaxation times (T1) and nuclear Overhauser enhancements (η) were measured for dithiarsolanes. The contributions of dipolar (T) and spin‐rotation (T) mechanisms were determined. The T1 data were analysed to obtain information on the relative order of magnitude of the internal motion rates. The calculations were based on the isotropic, with internal rotation about the AsPh bond, model of reorientation. In cis, trans‐2‐phenyl‐4‐methyl‐1,3,2‐dithiarsolane, the internal rotation of the phenyl ring is c. three times faster than overall molecular reorientation. The internal motion of the arsolane ring is slightly slower than the phenyl ring rotation. The rotation of the methyl groups in the compounds appears to be considerably hindered, with rotation energy barriers of c. 10 kJ mol−1. In contrast to the situation in the 4‐methyldithiarsolane, the internal motion of the arsolane ring is twice as fast as the internal rotation of the phenyl ring for the methyl‐unsubstituted analogue, 2‐phenyl‐1,3,2‐dithiarsolane.

ChemInform Abstract: OXIDATIVE‐ADDITION AND REDUCTIVE‐ELIMINATION REACTIONS INVOLVING PLATINUM COMPLEXES AND TETRAORGANOTIN COMPOUNDS

AbstractDie Tetraorgano‐Sn‐Verbindungen (II) reagieren mit den cis‐Ethylen‐diphosphin‐Pt(O)‐Komplexen (I) zu den cis‐Arylstannyl‐ Pt(II)‐Komplexen (IIIa) und (IIIb).

Antimony-121 mössbauer and infrared spectral study on halophenylantimonate(III) Compounds

The synthesis and the 121Sb Mössbauer and infrared spectra of halophenylantimonates(III) M[PhSbX 3] (M  Me 4N, Ph 4As;X  Cl, Br, I) are reported, and the spectral data are discussed and compared with those of SbX 4 and other related systems. The results are in accord with the participation of the antimony 5s electrons in the SbPh bond. In the interpretation of the electric field gradient, the contributions to V zz from both the lone pair and the SbPh bond electron densities are assumed to be dominant.

Oxidative-addition and reductive-elimination reactions involving platinum complexes and tetraorganotin compounds

Tetraorganotin compounds SnMe4–nRn(R = aryl, n= 1–3) react with [Pt(C2H4)(PPh3)2] to form cis-[PtR-(SnMe4–nRn–1)(PPh3)2][n= 1(1) or 2(2)], but with an excess of SnMe3R (if R has no 2-substituents) the complex cis-[PtR(SnMe2R)(PPh3)2](2) is also formed by insertion of (1) into an Sn–Me bond of a second molecule of SnMe2R and elimination of SnMe4. Complex (1) reacts with SnMe2R2 to form (2) and SnMe3R and both of these reactions are reversible: (1) and SnMe3R are formed from (2) and SnMe4, and (1) and SnMe2R2 are formed from (2) and SnMe3R. The system catalyses the redistribution 2SnMe3R ⇌ SnMe2R2+ SnMe4, and (2) catalyses redistribution of aryl groups (R,R′) between SnMe2R2 and SnMe2R′2. Mechanisms involving platinum(IV) intermediates are proposed for these and several related reactions. Reactions of (1) and (2)(R = Ph) with a number of oxidative-addition reagents are reported. With organotin chlorides SnMe3Cl, SnMe2Cl2, and SnPh2Cl2, (1) and (2) form bis(triphenylphosphine)platinum(II) complexes in which a Pt–Ph bond is retained and in which the number of chlorine atoms on the stannio-ligand is less than or equal to that in the tin(IV) reagent. The mechanism of these processes also appears to involve platinum(IV) intermediates and to be consistent with the normal order of reactivity Sn–Cl > Sn–R > Sn–Me. Some complexes (1) and (2) have been isolated and characterised and 31P-{1H} n.m.r. parameters are reported for all complexes.

Organoplumbio complexes of platinum(II)

The complex [Pt(C 2H 4)(PPh 3) 2] reacts with Pb 2Ph 6 to give cis-[PtPh(Pb 2Ph 5)(PPh 3) 2]; this decomposes in solution to cis-[PtPh(PbPh 3)(PPh 3) 2], which may also be obtained from the ethylene complex and PbPh 4. Lead compounds PbPhMe 3 and PbPh 3Br also give products of insertion into PbPh bonds, but PbMe 3Cl gives cis- and trans-[PtCl(PbMe 3)(PPh 3) 2]. The complex trans-[Pt(PbPh 3) 2(PEt 3) 2] reacts with 1,2-bis(diphenylphosphino)ethane (DPPE) to give [Pt(PbPh 3) 2(DPPE)] which readily decomposes in dichloromethane in presence of PEt 3 to give [Pt(PbPh 3)(PEt 3)(DPPE)]Cl and [PtPh(PEt 3)(DPPE)]Cl. The complex trans-[PtCl(PbPh 3)(PEt 3) 2] was detected in the products of reactions between trans-[PtCl 2(PEt 3) 2] and trans-[Pt(PbPh 3) 2(PEt 3) 2] or less than 2 moles of LiPbPh 3; it was not detected in the mixture after treatment of trans -[Pt(PbPh 3) 2(PEt 3) 2] with HCl. In contrast to an earlier report, we were unable to detect lead-containing complexes in the products of the reaction between trans-[PtHCl(PPh 3) 2] and Ph 3PbNO 3. The complexes and their decomposition products were identified by pre31P-{ 1H} NMR spectroscopy.

Infrared and ultraviolet absorption spectra of PO and HPO isolated in an argon matrix

Upon vacuum ultraviolet photolysis of Ar:PH 3:N 2O deposits at 14 K, PO is formed in sufficient concentration for observation of its vibrational fundamental absorption and of bands associated with three of its electronic transitions, and HPO is formed in sufficient concentration for the identification of both of its ground-state stretching fundamental absorptions. The infrared identifications are supported by studies of the products of the codeposition at 14 K of an Ar:PH 3 sample with an Ar:O 2 sample that had been passed through a microwave discharge. The matrix observations support the assignment of the B 2 Σ +-X 2 Π band system of PO as a valence transition. Detailed isotopic substitution studies have confirmed the assignment of the PH stretching fundamental of ground-state HPO near 2100 cm −1, implying a relatively weak and long PH bond. A four-constant valence force potential has been derived for HPO. Tentative infrared identifications of PO stretching absorptions of PO 2 and (PO) 2 are suggested.

Spatial structure of phosphorus-containing heterocycles. 23. 2-Phenoxy-1,3,2-dioxaphosphorinanes with four-coordinate phosphorus

1. The change in the valence state of the phosphorus atom influences the orientation with respect to the P-O(Ph) bond in 2-phenoxy-2-oxo(thiono)-1,3,2-dioxaphosphorinanes. 2. An orthogonal conformation is realized in the O-Ph fragment of the compounds investigated, regardless of the hybridization of the phosphorus.

Synthèse et propriétés chimiques du phényl-5-octahydro-1,2,3,4,6,7,8,9-dibenzophosphole

5-Phenyl-1,2,3,4,6,7,8,9-octahydrodibenzophosphole (L) has been synthesized by reacting DBU with the PhPBr2-1,1′-bicyclohexenyl cycloadduct. Its chemical properties have been compared with those of more classical phospholes. Its P-oxide and P-sulfide are monomeric. A double ring-expansion reaction is observed with benzoyl chloride as with simple phospholes. On the contrary we met a limited success with the P—Ph bond cleavage by K in THF and we did not succeed at all when attempting a P—Ph → P—tBu exchange by reaction with tBuLi. The corresponding phosphacymantrene has been obtained with Mn2(CO)10. σLFe(CO)4, σ,ηLFe2(CO)7 ans ηLOFe(CO)3 complexes have been obtained from the reactions of L or its P-oxide with Fe3(CO)12.

Structural studies in main group chemistry : XX. Structure and spectroscopic properties of triphenyliodomethyltin(IV)

The structure of the title compound has been determined from X-ray diffractometer intensity data using Patterson and Fourier techniques. Crystals are triclinic, space group P 1 , with a 7.3626(5), b 10.7516(2), c 13.2404(3) Å, α 106.12(40, β 94.81(6), γ 114.26(6)°, and are composed of discrete non-interacting Ph 3SnCH 2I molecules. The geometry at tin is only slightly distorted from ideal tetrahedral, with CSnC bond angles lying in the range 106.3(2) to 111.8(2)°. The mean SnC(Ph) bond distance (2.133(6) Å) is exactly the same as the SnCH 2I distance (2.134(6) Å). Thus the presence of the bulky, electronegative iodine substituent on the alkyl group has a negligible effect on the stereochemistry at tin. This observation is consistent with the narrow single line seen in the Mössbauer spectrum, but the 1H and 119Sn NMR data show that some perturbation of the electronic distribution occurs. Mass spectral data are also reported.