Jürgen Szameitat

Synthesis of η4-1,3-diphosphacyclobutadiene(η5-1,2-dicarbaborane)rhodium complexes; crystal structures of the compounds [NEt4][Rh(η4-But2C2P2)(η5-C2B9H11)], [Rh{η4-But2C2P2Au(PPh3)}(η5-C2B9H11)], and [Rh{η4-But2C2P2Co-(CO)2(η4-C4Me4)}(η5-C2B9H11)]

Treatment of a thf (tetrahydrofuran) solution of K[Rh(PPh3)2(η5-C2B9H11)] with ButCP, followed by addition of NEt4Cl, affords the salt [NEt4][Rh(η4-But2C2P2)(η5-C2B9H11)](3), the structure of which has been established by X-ray diffraction. Compound (3) reacts with [AuCl(PPh3)] and with [Co(CO)2(NCMe)(η4-C4Me4)][PF6] to afford, respectively, the complexes [Rh{η4-But2C2P2Au-(PPh3)}(η5-C2B9H11)](4) and [Rh{η4-But2C2P2Co(CO)2(η4-C4Me4)}(η5-C2B9H11)](5). The structures of the products (4) and (5) have also been determined by X-ray diffraction. In all three compounds the rhodium is η5 ligated by a nido-icosahedral C2B9H11 fragment, and by a 1,3-diphosphacyclobutadiene group. Within the latter the P–C distances are equal, and the four-membered CPCP rings are close to planar. In the compounds (4) and (5) a phosphorus atom in the η4-But2CP2 group co-ordinates to the Au(PPh3) and the Co(CO)2(η4-C4Me4) groups, respectively. The n.m.r. data (1H, 13C-{1H}, 11B-{1H}, and 31P-{1H}) are reported, and where appropriate discussed.

Synthesis, crystal structure, and reactivity of the (η4-1,3-diphosphacyclobutadiene)(η5-1,2-dicarbaborane)rhodium complex [NEt4][Rh(η4-P2C2But2)(η5-C2B9H11)]

Tetrahydrofuran solutions of K[Rh(PPh3)2(η5-C2B9H11)] react with ButCP and NEt4Cl to afford the salt [NEt4][Rh(η4-But2 C2P2)(η5-C2B9H11)], which with [AuCl(PPh3)] and [Co(CO)2(NCMe)(η4-C4Me4)][PF6] yields the compounds [Rh(η4-But2C2P2MLn)(η5-C2B9H11)][MLn= Au(PPh3) or Co(CO)2(η4-C4Me4)]; all structurally identified by X-ray diffraction.

Reaktive EC (pp) τ-systeme: XV. Synthese und molekülstruktur des pentacarbonylchrom-komplexes von 2-(pentafluorethyl)-3-fluor-3-(trifluormethyl)-2-phosphabicyclo[2.2.1]hept-5-en

Abstract Thermolysis of Me 3 SnP(C 2 F 5 ) 2 yields only one of the two possible isomers of the phosphaalkene F 5 C 2 PC(F)CF 3 ( 1 ) and the [2 + 4] cycloaddition of 1 to cyclopentadiene again leads to only one isomeric species ( 2 ) [2]. To elucidate the structures of 1 and 2 the crystalline complex (CO) 5 Cr(C 9 H 6 F 9 P) ( 3 ) of the bicyclic phosphane 2 has been prepared by the reaction of 2 with Cr(CO) 5 THF. An X-ray diffraction study of the structure (space group P 1 ; a 8.024(6), b 9.084(6), c 14.190(1) A; α 73.62(3), β 71.20(3), γ 71.76(4)°; Z = 2) reveals that the substituents F(1) and Cr(CO) 5 in 3 occupy anti positions on the PC(6) bond, thus confirming exo -isomer structure for the cycloadduct 2 and, if a concerted mechanism for the [2 + 4] cycloaddition is assumed, Z configuration for 1 . These results are in accord with structural conclusions on the basis of 19 F NMR data.

Chemistry of polynuclear metal complexes with bridging carbene or carbyne ligands. Part 96. Reactions with phospha-alkynes; crystal structures of [WFe{µ-C(C6H4Me-4)PC(But)(CO)5}(η-C5Me5)] and [MoFe{µ-C(C6H4Me-4)C(But)P}(µ-CO)(CO)3(PMe3)(η-C5H5)]

The electronically unsaturated dimetal compound [WFe(µ-CC6H4Me-4)(CO)5(η-C5Me5)] reacts with the phospha-alkynes R′CP (R′= But or Pri) in thf (tetrahydrofuran) below room temperature to give the complexes [WFe{µ-C(C6H4Me-4)PC(R′)}(CO)5(η-C5Me5)]. The structure of the species with R′= But has been determined by X-ray diffraction. The metal–metal bond [W–Fe 2.720(2)A] is spanned by the bridging group such that all three atoms of the CPC chain are attached to the iron atom [Fe–CC6H4Me-4 2.11 (2), Fe–CBut 2.14(1), and Fe–P 2.336(5)A] but only the terminal carbons ligate the tungsten centre [W–CC6H4Me-4 2.18(2), W–CBut 2.22(1)A]. The iron carries three CO groups, and the tungsten is co-ordinated by two CO ligands and the C5Me5 ring. Reactions between the phospha-alkynes and the dimetal compounds [MFe(µ-CC6H4Me-4)(CO)4(PMe3)(η-C5H5)](M = Mo or W) in thf afford under mild conditions the complexes [MFe{µ-C(C6H4Me-4)PC(R′)}(CO)4(PMe3)(η-C5H5)](M = Mo, R′= But or Pri; M = W, R′= But), containing a similar bridge system. The two molybdenum–iron compounds readily isomerise in solution, yielding the species [MoFe{µ-C(C6H4Me-4)C(R′)P}(µ-CO)(CO)3(PMe3)(η-C5H5)]. An X-ray diffraction study on one of the isomers (R′= But) revealed an asymmetric unit containing two crystallographically independent molecules of similar geometry. The Mo(1)–Fe(1) bond [2.710(1)A] is bridged by a carbonyl ligand and by the C(C6H4Me-4)C(But)P unit. All these atoms of the CCP group are bonded to the molybdenum atom [Mo(1)–CC6H4Me-4 2.290(4), Mo(1)–CBut 2.353(5), and Mo(1)–P(1) 2.527(2)A], but only the P and CC6H4Me-4 groups are attached to the iron [Fe(1)–CC6H4Me-4 2.017(5), Fe(1)–P(1) 2.302(2)A]. The Mo atom carries the η-C5H5 ring and a CO ligand but the latter is bent [Mo(1)–C–O 168.4(4)°] towards the µ-P atom [C ⋯ P 2.380(5)A]. The Fe atom is co-ordinated by two terminally bound CO groups and the PMe3 ligand [Fe(1)–P(2) 2.246(2)A]. The n.m.r. spectra (1H, 13C-{1H}, and 31P-{1H}) of the new compounds are reported and discussed.

Fluorophosphaalkenes - New Versatile Reagents

Abstract The synthesis of substituted fluorophosphaalkenes RP=CFR′ with a variety of groups R and R′ is discussed. The reactivities (self-addition, HX addition, [2+4] cycloaddition with 1,3-dienes) and the coordination chemistry of selected compounds have been explored.

Reaktive EC (p—p) π-Systeme: XXV. Isolierung und Molekülstruktur eines ungewöhnlichen Dirhodiumkomplexes: [(η5-C5Me5)(CO)RhI(F3CPCF2)2RHIII(CO)(η5-C5Me5)]☆

Perfluoro-2-phosphapropene F3CPCF2 (1) reacts with Rh2(μ-CO)2(η5-C5Me5)2 (2) at −78°C in dichloromethane yielding a complicated mixture of products containing F3CPCF2 and Rh(CO)(C5Me5) units. One of the main products (ca. 40% of the mixture) can be isolated by column chromatography. Composition and structure of this compound 3 have been determined by analytical (C, H) and specroscopic investigations (IR, MS, 1H-, 19F-, 31P-NMR) as well as by an X-ray diffraction study. The product turnsout to be a novel dirhodium complex 3C (structure in Introduction) which is also produced by the reaction of 2 with the trans-diphosphetane (F3CPCF2)2 (4) under the conditions mentioned above.

Reaktive E =C (p—p)π-Systeme, X Darstellung und Reaktivität von Perfluor-3-phosphapent-2-en / Reactive E = C (p-p)π-Systems, X Preparation and Reactivity of Perfluoro-3-phosphapent-2-ene

Abstract Perfluoro-3-phosphapent-2-ene F5C2 P =C (F )CF3 (1) has been prepared for the first time by thermal elimination of trimethyltin fluoride Me3SnF from trim ethylstannyl-bis(pentafluoroethyl)- phosphane Me3SnP(C2F5) 2 at 300 °C/10−3 Torr. 1 is found to be less stable than F3CP = CF2 in dilute solution at room temperature, forming several 1,3-diphosphabutane dimers. Reactivity studies accomplished till now include (i) the dienophilicity of 1 in [2+4] cycloaddition reactions with butadiene, 2,3-dim ethylbutadiene, cyclopentadiene, 1,3-cyclohexadiene, 2-methylbutadiene, and 2-methylfuran leading by a concerted mechanism to the Diels-Alder-adducts 2-7 in about 80% yield, (ii) the addition of proton acidic compounds HX (X = OMe, Br, NMe2, NEt2) to the PC double bond affording chiral phosphanes of the type F5C2 P(X)CF(CF3)H [X = OMe (8). Br (9). NMe2 (10). NEt2 (11)]. thus proving a stronger polarity δ+P =δ−C for 1 than for F3CP = CF2. New compounds have been characterized by NMR and MS measurements.