The reactivity of singly and doubly selenium-bridged complexes containing two Cp*Rh(CO) fragments (Cp" = q5-C,Me,) has been investigated under various conditions. The addition of SO, to Cp*,Rh,(CO),(p-Se)gives a novel p-SeSO, ligand, whose structure was determined by an X-ray diffraction study. The complexes Cp*,Rb,(CO),(p-E), (E = S, Se) undergo a disproportionation reaction in solution: the clusters Cp*,Rh,( p3-CO)(p3-E) were isolated and structurally characterized, whereas the remaining soluble, presumably mononuclear species was only detected by IR spectroscopy. In contrast, Cp*,Rh2(CO),(p-Se), dimerizes upon warming to give Cp*,Rh,(~3-Se), with the loss of its CO groups. The 72-e heterocubane clusters Cp*,CozRh,Se, and Cp*,Co,Se, have been synthesized from Cp*,CoM(CO),Se, (M = Co, Rh). The cluster Cp*,Rh,(CO), was isolated as a further byproduct from the synthesis of C~*,Rh,(co)~.The IR spectra and the X-ray crystallographic study show that the complex contains one p3-C0 and two p2-C0 ligands. Zusammenf assung Es wurde dieReal&&it von einfach und doppelt selenverbrtickten Komplexen mit Cp*Rh(CO)-Fragmenten (Cp" = $'-C,Me,) unter verschiedenen Gesichtspunkten untersucht. Die Addition von SO, an Cp*,Rh,(CO),(&3e) verlauft unter Bildung eines neuartigen p-SeSO,-Liganden, dessen Struktur durch Rijntgenstrukturanalyse bestimmt wurde. Die Komplexe Cp*2Rhz(CO),(~-E),(E = S, Se) unterliegen in LGsung einer Disproportionierungsreaktion: Die Cluster Cp*,Rh,( p3-CO)(p3-E) konnen isoliert und strukturell charakterisiert werden, w%hrend eine in

Key Words: Antiviral agents / Aristeromycin / Cyclaradine / (+)-( 1 R,4R)-5-Norbornen-2-one / 2-Norbornanones, 5,6-dihydroxy- (?) was prepared in 78.5% yield by oxidative degradation of (+)-(1R)-endobicyclo[2.2.l]hept-5-ene-2-carboxylic acid (4) by using an improved procedure for the oxidation of the dianion of 4 with dioxygen. Dihydroxylation of 7 with osmium tetroxide furnished the cis exo addition product 8c and, via reversible retro aldol reaction, the trans isomer 8 t which was characterized by X-ray crystal structure analysis. 8c was transformed in four reaction steps into the lactone 2 which is a known starting material for a synthesis of the antiviral antibiotic aristeromycin (1). 8 t is a potential starting material for syntheses of carbocyclic analogues of arabinofuranosyl nucleotides, e. g., the antiviral agent cyclaradine (3). able for a synthesis of the antiviral agent cyclaradine (3)L41 was also obtained. (+)-(lR,4R)-Bicyclo[2.2.1]hept-5-en-2-one (-) -Aristeromycin(+)-( 1R)-endo-5-Norbornene-2-carboxylic acid (4), prepared via asymmetric Diels-Alder yields (+)-(lR)-5-norbornen-2-one (7) via a simple three-step sequence (Scheme 1) involving as a key step the oxidation of the dianion of 4 with dioxygen at low temperature in the presence of triethyl phosphite to give a mixture of diastereomeric a-hydroxy carboxylic acids 5. Several procedures have been published for effecting this Initially we experienced difficulties and, therefore, we explored several published procedures and variants of our own (cf Table 1). Excellent, reproducable results were obtained under the conditions given under entry 5 in Table 1. The subsequent steps to (+)-7 via 6 were carried out as described by Paquette[6b]. Because of the extreme volatility of (+)-7 we used a simple low temperature high vacuum condensation technique to remove the solvent and for purification. The value of the optical rotation of the bicyclic ketone (+)-7 was in excellent agreement with values reported in the literature (cf. Experimental).Our synthetic plan called for cis-dihydroxylation of the double bond of 7 and subsequent oxidative cleavage of the C2-C3 bond. To our surprise, reaction of 7 with osmium tetroxidelN-methylmorpholine N-oxide['] gave mainly the trans-diol 8t (ratio 8 t : 8 c ca. 4: 1). The constitution of the reaction products was deduced from the 'H and I3C NMR spectra. However, spectroscopy did not allow unambiguous assignment of the relative configurations. The cis-ex0 configuration of 8 c has been confirmed by the synthesis of

Cophotolyse von p3-AsCp3M03(C0)6 (1) und CpCo(C0h (2) (Cp = Cyclopentadienyl ergibt den Cluster ~-AsCp,Co,Mo-(CO), (3). dessen Metallgeriist isostrukturell zu Spiropentan ist, und den trigonal-pyramidalen Cluster ~,-ASC~~CO~MO(CO)~ (4), wahrend die thermische Umsetzung zu einem hoher aggregierten, CO-armeren Produkt fuhrt, dem trigonal-bipyramidalen p3-A S C~~C O~M~( C O )~ (6a). Die thermische Reaktion von p3-AsCp;Mo3(CO),, (Cp' = Methylcyclopentadienyl) mit 2 ergibt die zu 6a analoge Verbindung ps-AsCp3Cp'Co3Mo(CO), (6 b). Von 3, 4 und 6b wurden Rontgenstrukturanalysen durchgefiihrt.Der von uns aus metallischem Arsen und [CpMo(C0)'I2 erstmals synthetisierte Cluster p3-AsCp,Mo3(CO), (1) ') zeigt eine bemerkenswerte Reaktionsvielfalt. Bereits dokumentiert wurden Additionen substitutionslabiler Ubergangsmetallfragmente am Arsenatom, Ersatz von Clusterbausteinen durch Fe(CO),-Einheiten", Offnung des Gerusts durch Reaktion mit dem Phosphorylid CH2= PPh3" sowie COChalkogenid-Ligandensubstitutionen').Hier berichten wir uber die photolytische und thermische Umsetzung von 1 mit C~C O ( C O )~ (2). 2 wurde als Reaktant ausgewahlt, da aus ihm unter photolytischen und thermischen Bedingungen Molekulteile entstehen4', die ihrerseits mit den Photolyseprodukten von 1 reagieren konnen. A. 1. Cophotolyse von 1 und 2Die Reaktanten werden in THF-Losung 10 Stunden bestrahlt. Nach saulenchromatographischer Aufarbeitung konnen die rotbraunen bzw. braunen Cluster 3 und 4 isoliert werden.Die Reaktion laBt sich in zwei Phasen einteilen: 1) Umwandlung der Ausgangsprodukte in teils faBbare, reaktive Intermedilre (Schema 1).2) Kombination der Intermediare zu den Endprodukten (Schema 2).Die Existenz von 2 a -e ist durch Untersuchungen von Vollhardt und Bergman4'' gesichert, als Nachweis fur das Vorhandensein von 1 a und 1 b sind folgende Ergebnisse heranzuzie hen:chromatographie isoliert und IR-spektroskopisch charakterisiert werden. Arsenic-Cobalt-Molybdenum Clusters by Photolytic and Thermal Reaction of W~-A S C~M O~( C O )~ with C~CO(CO)~ Cophotolysis of ~, -A S C~~M O~( C O )~(1) and CpCo(CO)z (2) (Cp = cyclopentadienyl) yields the cluster p4-AsCp,Co3Mo(C0), (3), the metal core of which is isostructural to spiropentane, and the trigonal-pyramidal cluster p3-AsCp3C02Mo(CO)3 (4), whereas thermal reaction leads to trigonal-bipyramidal ~, -A S C~~C O~M O ( C O )~ (6a). Thermal reaction of p3-AsCp;Mo3(CO)6 (Cp' = methylcyclopentadienyl) with 2 yields p3-AsCp3Cp'Co3Mo(CO), (6b), which is analogous to 61. Clusters 3,4, and 6b were characterized by means of X-ray structure analyses.

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Synthesis of Trinuclear Carbonylmanganates and Their Reaction Products with InCl3; X‐ray Structure Determinations of K3[Mn3(μ‐CO)2(CO)10], [(C6H5)4As]2[(μ‐H)Mn3(μ‐CO)10], [{(C6H5)3P}2N]2[μ‐H)Mn3(CO)12], [(C6H5)4As]2[{μ‐H)Mn3(CO)12}2(μ4‐In)] und [(C6H5)4As]2[{(μ‐H)Mn3(CO)12}(μ3‐In){Mn(CO)5}Cl] Mn2(CO)10 reacts with KOH in aqueous solution to give the potassium carbonylmanganate K3[Mn3(μ‐CO)2(CO)10] (1). The trianion 1 is isoelectronic with Fe3(CO)12 and is protonated with methanol to form the μ‐hydrido cluster [(μ‐H)Mn3;‐(CO)12]3⊖, which is precipitated with [{(C6H5)3P}2N]Cl as [{(C6H5)3P}2N]2[(μ‐H)Mn3(CO)12] (2), whereas the carbonyl‐bridged μ‐hydrido species [(μ‐H)Mn3(μ‐CO)2(CO)10]2⊖ seems to be trapped as the [(C6H5)4As]⊕ salt 3. The reaction of 3 with InCl3 yields the Mn‐In clusters [(C6H5)4As]2[{(μ‐H)Mn3(CO)12}2;‐(μ4‐In) (4) and [(C6H5)4As]2[{(μ‐H)Mn3(CO)12}(μ3‐In){Mn(CO)5}Cl] (5). X‐ray structure analyses have been carried out for the compounds 1 – 5.