C-Halophosphaalkenes (1, 2) were prepared in high yield by a one-pot synthesis from HCX3 or CI4 and Mes* PCl2 (Mes* supermesityl 2,4,6-tri-tert-butylphenyl). The C-iodophosphaalkenes Mes* P Cl2 (1 C) and Mes*P CHI (2c) undergo halogen-metal exchange with n-BuLi at low temperatures. The resulting carbenoids Mes*P CILi (11 c) and Mes*P CHLi (6) reacted with ClMMe3 (M Si, Ge, Sn) to give Mes*PCIMMe3 [(Z)-13: M Ge; (Z)-14: M Sn] or Mes*P CHMMe3 (8–10), respectively. Further reaction of (Z)-13 and (Z)-14 with nBuLi and ClMMe3 gave Mes*PC(MMe3 (18: MGe; 19: M Sn). The carbenoid (Z)-11 c decomposed at −85°C; instead of the expected “phosphaisonitrile” Mes*P C : (21), only Mes*CP (15) was obtained which lends experimental support to the theoretically predicted instability of 21.

Synthesis and Reactions of P-Supermesityl-C-halophosphaalkenes

Ylidyl-dihalophosphanes Provide Structural Snapshots on Their Way to Dissociation

The reaction of phosphonium ylides with phosphorus trihalides has been studied for the synthesis of ylidyl-dihalophos-phanes (= dihalophosphanyl ylides) Ph3PCRPX23, X = Cl, and 9, X = Br. Compounds 3, R = aryl, are readily prepared from the phosphonium bromides [Ph3PCH2R]Br, compounds 3, R = alkyl, SiMe3 or PCl2, and 9 are obtained from silylylides Ph3PCRSiMe3, compound 3, R = PPh3+ results from the addition of PCl3 to the hexaphenylcarbodiphosphorane. A (β-morpholinovinyl)dichlorophosphane 12 has also been prepared. Ylides 3 are oxidized by sulfur and selenium and are converted to ylidyl-chlorophosphenium (= chloro-phosphaalkenyl-phosphonium) salts [Ph3PCRPCl]AlCl410. In the 31P-NMR spectra of 3 and 9 the geminal coupling 2JPP indicates the phosphorus lone pair to be synperiplanar to the phosphonio group. In one case the P(III)C rotation barrier has been estimated from VT-31P-NMR spectra. By X-ray crystallography the structures of 3, R = Me, 2,6-Cl2C6H4, 4-NO2C6H5, PCl2, of 9, R = Me (two molecules), SiMe3, of an ylidyl-selenophosphonyl dichloride (11b), and of 12 have been analyzed. They provide representatives for the full range of rotation from the symmetric conformer with two equal PX bonds to the conformer with one PX bond perpendicular to the PCP plane and with this bond being extremely elongated. Thus, they map out the pathway to PX bond breaking. On this way the initial charge transfer from the ylidic carbon to the antibonding PX orbital ends up in a π donation and PX dissociation.

Ylidyl-dihalogenphosphane – Strukturbilder einer sich anbahnenden Dissoziation

The nature of chemical bonding in the complex carbides Sc3[Fe(C2)2] (1) and Sc3[Co(C2)2] (2) has been explored by combined experimental and theoretical charge density studies. The structures of these organometallic carbides contain one-dimensional infinite TC4 (T = Fe, Co) ribbons embedded in a scandium matrix. Bonding in 1 and 2 was studied experimentally by multipolar refinements based on high-resolution X-ray data and compared to scalar-relativistic electronic structure calculations using the augmented spherical wave method. Besides substantial covalent T−C bonding within the TC4 ribbons, one also observes discrete Sc−C bonds of noticeable covalent character. Furthermore, our study highlights that even tiny differences in the electronic band structure of solids might be faithfully recovered in the properties of the Laplacian of the experimental electron density. In our case, the increase of the Fermi level in the organometallic Co(d9) carbide 2 relative to its isotypic Fe(d8) species 1 is reflected in ...

Experimental electron density of the complex carbides Sc3[Fe(C2)(2)] and Sc3[Co(C2)(2)].

Metal flux synthesis in a low-melting eutectic mixture of lanthanum and nickel has produced a family of complex intermetallic carbide phases. La(21)Fe(8)M(7)C(12) (M = Sn, Bi, Sb, Te, Ge) has a new cubic structure featuring tetrahedra of iron atoms capped with carbon on each edge. These tetrahedra are surrounded by a La/M framework and are therefore isolated from each other. The antiferromagnetic coupling of the iron atoms is frustrated by their ideal tetrahedral arrangement; this is evidenced by magnetic susceptibility measurements on the La(21)Fe(8)Sn(7)C(12) analogue. Deviations from Curie-Weiss behavior begin at 100 K; variation in field-cooled vs zero-field-cooled behavior is seen at 5 K indicative of magnetic ordering. AC susceptibility data indicate that the temperature of this transition is frequency-dependent, behavior characteristic of spin glass systems.

Spin Glass Behavior of Isolated, Geometrically Frustrated Tetrahedra of Iron Atoms in the Intermetallic La21Fe8Sn7C12

Properties of Chalcogen–Chalcogen Bonds, XV1). - Lithium 2,4,6-Tri-tert-butylphenylselenide: Synthesis, Structure, and Reactions with Formation of Se – P, Se – C, Se – Si, Se – Sn, and Se – Au Bonds



Bis(2,4,6-tri-tert-butylphenyl)diselenide (1) is reduced by lithium triethylhydridoborate to give lithium 2,4,6-tri-tert-butyl-phenylselenide (2) in high yield. 2 crystallizes with three molecules of tetrahydrofuran coordinated to lithium ([2(THF)3] 2a, space group P&1macr; Z =4). The monomeric compound 2a contains four-coordinate lithium bonded to two-coordinate selenium. 2 (LiSeR) reacts with the nonmetal and metal halides tBu2PCl, CH2Cl2, Me3SiCl, Me3SnCl, and Ph3PAuCl to give tBu2PSeR (3), RSeCH2Cl (4), (RSe)2CH2 (5), Me3SiSeR (6), Me3SnSeR (7), and the novel gold(I) selenophenolate derivative Ph3PAuSeR (8)(R = 2,4,6-tri-tert-butylphenyl).

Lithium-(2,4,6-tri-tert-butylphenylselenid); Erzeugung, Struktur und Reaktionen unter Knüpfung von Se –P-, Se – C-, Se – Si-, Se – Sn- und Se – Au-Bindungen

Preparation and crystal structure of superconducting Y2FeC4 and isotypic lanthanoid iron carbides

New aspects in the chemistry of fluorophosphaalkenes1: stable phosphorus ylides R3'P=C (NR2) P (F) CF3 from F3CP=C (F) NR2

Die He(I)-Photoelektronen (PE)-Spektren von (CH3)2PSCH3 (1), (CH3)2AsSCH3 (2), (CH3)2AsSeCH3 (3) und (CH3)2PsSeCH3 (4) wurden gemessen. Die Zuordnung der ersten funf Banden erfolgte durch Vergleich mit den PE-Spektren der Verbindungen (CH3)3X, (CH3)2XX(CH3)2 (X = P, As), sowie (CH3)2Y und CH3YYCH3 (Y = S, Se). Auserdem wurden die gemessenen Ionisationspotentiale mit berechneten Orbitalenergien (CNDO, INDO, MNDO) verglichen. Die ersten beiden Banden in den PE-Spektren von 1–4 konnen Ionisierungen zugeordnet werden, bei denen das Elektron aus Linearkombinationen der einsamen Elektronenpaare stammt.



The He(I) Photoelectron Spectra of (CH3)2PSCH3, (CH3)2AsSCH3, (CH3)2AsSeCH3 and (CH3)2PSeCH31)



The He(I) photoelectron (PE) spectra of (CH3)2PSCH3 (1), (CH3)2AsSCH3 (2), (CH3)2AsSeCH3 (3) and (CH3)2PSeCH3 (4) have been recorded. The assignment of the first five bands is based on a comparison with the PE spectra of (CH3)3X, (CH3)2XX(CH3)2 (X = P, As) as well as of (CH3)2 and CH3YYCH3 (Y = S, Se). Additionally the measured ionization potentials have been compared with calculated orbital energies (CNDO, INDO, MNDO). The first two bands of the PE spectra of 1–4 are due to ionization events from linear combinations of the lone electron pairs.

Die He(I)-Photoelektronenspektren von (CH3)2PSCH3, (CH3)2AsSCH3, (CH3)2AsSeCH3 und (CH3)2PSeCH31)

ペルフルオロメチル‐元素‐配位子 21 RnE‐ERm(R=CH3CF3;E=P,As,S,Se;n,m=1,2)の型の有機元素‐元素‐化合物の調製およびその特性

Reactions de F 3 CP=CF 2 avec Me 3 GeH, Me 3 SnH et (C 5 R 5 )(CO) 3 MH (M=Cr,Mo,W; R=H,Me)

J. Grobe

Papers

Preparation and crystal structure of superconducting Y2FeC4 and isotypic lanthanoid iron carbides

New aspects in the chemistry of fluorophosphaalkenes1: stable phosphorus ylides R3'P=C (NR2) P (F) CF3 from F3CP=C (F) NR2

Die He(I)-Photoelektronenspektren von (CH3)2PSCH3, (CH3)2AsSCH3, (CH3)2AsSeCH3 und (CH3)2PSeCH31)

ペルフルオロメチル‐元素‐配位子 21 RnE‐ERm(R=CH3CF3;E=P,As,S,Se;n,m=1,2)の型の有機元素‐元素‐化合物の調製およびその特性

Reaktive E=C(p-p)π-Systeme. XI: Hydrometallierungsreaktionen des Perfluor-2-Phosphapropens F3CP=CF2