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Immobilization of ortho-metalated dirhodium(II) compounds has been achieved by a carboxylate interchange reaction between (M)-Rh2(l-protos)2[(p-XC6H3)P(p-XC6H4)2]2 diastereoisomers and carboxyethylpolystyrene polymer (PS-C6H4(CH2)2CO2H). The immobilized chiral catalysts have been tested in the standard reaction of asymmetric cyclopropanation of styrene with ethyl diazoacetate, giving higher yields than homogeneous chiral trifluoroacetate derivatives, but their diastereo- and enantioselectivities were lower. Some of the immobilized catalysts have proved to be very robust. The catalytic behavior of (M)-Rh2(O2C(CH2)2C6H5)2[(p-XC6H3)P(p-XC6H5)2]2 compounds has been studied as a model for the immobilized catalysts.

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The thermal reaction of dirhodium tetraacetate with tris(3-thienyl)phosphine (3TP), diphenyl(3-thienyl)phosphine (3TPPh 2 ), and diphenyl(2-thienyl)phosphine (2TPPh 2 ) gives rise to mono-cyclometalated and bis-cyclometalated compounds; the latter can have a head-to-head (H-H) or head-to-tail (H-T) configuration. Bis-cyclometalated compounds with H-T configuration can be prepared in high yield under photochemical conditions or by combining irradiation with subsequent thermal treatment in acetic acid. The reactivity order of aromatic ring C-H activation is phenyl < 2-thienyl , 3-thienyl, which leads to a selective activation of the thienyl ring. Thus, only one mono-cyclometalated compound is obtained from the thermal reaction with 3TPPh 2 , and activation of the thienyl ring competes favorably with activation at the phenyl rings in the case of 2TPPh 2 . The reaction of these mono-cyclometalated compounds with d 4 -acetic acid was monitored by 1 H NMR spectroscopy, which demonstrates that the H/D exchange occurs during the demetalation step. The energy values calculated (DFT) for the different compounds agree with the experimental results.

The reaction of tris (2-thienyl)phosphine (1) with dirhodium(II) acetate in a 9:1 refluxing toluene/acetic acid mixture for 2 h leads to the formation of two metalated compounds. The structure of one of them contained two new orthometalated phosphines in a head-to-head arrangement, and, surprisingly, the metalated thiophene rings, but not the nonmetalated ones, were rearranged to a 3-thienyl structure. Both types of dirhodium compounds were assessed in a catalytic α-diazo ester transformation.

1,2,3,4λ5-Triazaphosphinine 1 reacts with PdCl2(PhCN)2 and W(CO)5(THF) at room temperature, affording, according to 31P NMR spectroscopy, η1-triazaphosphinine complexes 3 and 5, which after elimination of dinitrogen give the bis(η1-azaphosphete)palladium(II) complex 4 and (η1-azaphosphete)W(CO)5 complex 6, in 65% and 88% yield, respectively. Complex 4 can also be obtained in 90% yield by addition of PdCl2(PhCN)2 to 1,2λ5-azaphosphete 2. Addition of cis-Mo(CO)4(pip)2 to 1 leads to (η1-triazaphosphinine)Mo(CO)4(pip) complex 7, which was isolated in 70% yield. In solution, at room temperature for 2 days, 7 transforms into to η1-(five-membered cyclophosphazene)Mo(CO)5 complex 9 in 45% yield. When 2 equiv of W(CO)5(pip) is added to 1, complex 10 featuring a five-membered cyclophosphazene bonded to W(CO)5(pip) via a hydrogen bond is isolated in 80% yield. 1,2λ5-Azaphosphete 2 reacts with piperidine, affording five-membered phosphazene ring 11 in 95% yield, which by subsequent treatment with Mo(CO)5(pip) and W(CO)5(pip) gives complexes 9 (75% yield) and 10 (83% yield), respectively. Schwartz's reagent reacts with 1, affording five-membered zirconacyclophosphazene 12 in 45% yield. Complexes 4, 7, 10, and 12 are characterized by single-crystal X-ray analyses. These results as a whole demonstrate that in contrast with (E)-phosphazides which behave as four-electron donors via the α- and γ-nitrogen atoms and which are stabilized by complexation, (Z)-phosphazides, such as the 1,2,3,4λ5-triazaphosphinine 1, act as two-electron donors via the β-nitrogen atom, and are destabilized by the metal with respect to nitrogen elimination.

The alkenyl complexes [Ru{(E)‐C(CO2Me)=C(H)R}(η5‐C9H7){κ2‐P,P‐(S)‐peap}] [R = CO2Me (3), H (4)], [Ru{(E)‐CH=C(H)Ph}(η5‐C9H7){κ2‐P,P‐(S)‐peap}] (5) have been prepared by reaction of the hydride complex [RuH(η5‐C9H7){κ2‐P,P‐(S)‐peap}] (2) [(S)‐peap = (−)‐(S)‐N,N‐bis(diphenylphosphanyl)(1‐phenylethyl)amine] with an equimolar amount of dimethyl acetylenedicarboxylate, or with an excess of the terminal alkynes methyl propiolate or phenylacetylene. Similarly, vinylalkenyl complexes 6a−d have been synthesized by the regio‐ and stereoselective reaction of the hydride complex 2 with 1‐ethynylcycloalkynols. Protonation of the vinylalkenyl moiety of complexes 6a,c,d with HBF4·OEt2 in diethyl ether afforded the cationic alkenylalkylidene complexes 7a−c. The structures of complexes [RuH(η5‐C9H7){κ2‐P,P‐(S)‐peap}] (2) and [Ru{(E)‐C(CO2Me)=CH(CO2Me)}(η5‐C9H7){κ2‐P,P‐(S)‐peap}] (3) have been determined by X‐ray diffraction methods. The catalytic activity of (alkenylalkylidene)(indenyl)ruthenium(II) complexes 7a−c, 8 and 9 in the ring‐closing metathesis (RCM) of diethyl diallylmalonate has been examined. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)