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The trihalophosphane complexes LnMPHal3 (LnM = Cp(CO)2Mn, (CO)5Cr, (CO)5W; Hal = Cl, Br), upon treatment with Co2(CO)8, mainly yield clusters of the type Co3(CO)9(μ4-P)MLn with the (μ3-P)Co3(CO)9) unit acting as ligand. The analogous arsenic compound Co3(CO)9(μ4-As)Cr(CO)5 is obtained from the arsinidine complex [(CO)5Cr]2AsCl with NaCo(CO)4. In addition to the syntheses and reactios of these clusters several reactions leading to clusters with μ4-P-, μ4-As-, μ4-PR- and μ2-PR2 groups by reductive dehalogenation of coordinated halophosphanes are reported. The different types of compounds are documented by six X-ray-structure analyses.

Reaction of [Fe 2 (CO) 9 ] with a half molar amount of R 2 PYPR 2 (Y = CH 2 , R = Ph, Me, OMe or OPr i ; Y = N(Et), R = OPh, OMe or OCH 2 ; Y = N(Me), R = OPr i or OEt) leads to the ready formation of a product which on irradiation with ultraviolet light rapidly decarbonylates to the heptacarbonyl derivative [Fe 2 (μ-CO)(CO) 6 {μ-R 2 PYPR 2 }]. Treatment of the latter with a slight excess of the appropriate ligand results, under photochemical conditions, in the formation of the dinuclear pentacarbonyl complex [Fe 2 (μ-CO)(C)) 4 {μ-R 2 PYPR 2 } 2 ] but under thermal conditions in the formation of the mononuclear species [Fe(CO) 3 {R 2 PYPR 2 }]. Reaction of [Ru 3 (CO) 12 ] with an equimolar amount of (RO) 2 PN(R′)P(OR) 2 (R′ = Me, R = Pr i or Et; R′ = Et, R = Ph or Me) under either thermal or photochemical conditions produces [Ru 3 (CO) 10 {μ-(RO) 2 PN(OR) 2 }] which reacts further with excess (RO) 2 PN(R′)P(OR) 2 on irradiation with ultraviolet light to afford the dinuclear compound [Ru 2 (μ-CO)(CO 4 {μ-(RO) 2 PN(R′)P(OR) 2 } 2 ]. The molecular structure of [Ru 2 (μ-CO)(CO) 4 {μ-(MeO) 2 PN(Et)P(OMe) 2 } 2 ], which has been determined by X-ray crystallography, is described.

Der Chlorarsiniden-Komplex ClAs[Cr(CO)5]2 (1) reagiert mit OH-funktionellen Chelatliganden HO B wie 2,4-Pentandion, 1,3-Diphenyl-1,3-Diphenyl-1,3-propandion, Tropolon oder 8-Hydroxychinolin unter Chlor-Substitution und Bildung stabiler Arsen (+1)-Chelatkomplexe B OAs[Cr(CO)5]2 (2a–d). Eine Rontgenstrukturanalyse des Acetylacton-Derivates 2a belegt die Konstitution der Chelatkomplexe. Reactions to the Chloroarsinidene Complex ClAs[Cr(CO)5]2 with Bidentate Chelating ligands The chloroarsinidene complex ClAs[Cr(CO)5]2 (1) undergoes chlorine substitution with OH-functional chelating ligands HO B such as 2,4-Pentanedione, 1,3-diphenyl-1,3-diphenyl-1,3-propanedione, tropolone, or 8-hydroxyquinoline to form stable arsenic (+1) chelate complexes B OAs[Cr(CO)5]2 (2a–d). An X-ray structure analysis of the acetylactone derivative 2a exemplifies the constitution ot the chelate complexes.

The compound As2[W(CO)5]3 is obtained from AsCl3 and Na2W2(CO)10 or (CO)5 WTHF respectively. Its wheel-type molecular framework as determined by X-ray analysis has D3h symmetry with three W(CO)5 groups surrounding the axial As2 ligand (d(AsAs) = 227.9 pm) which thus acts as a six-electron donor. This unusual bonding situation is analysed by EHT methods.

Compounds RXHal2 (X = P, As, Sb) react with Na2[M2(CO)10] (M = Cr, Mo, W) to yield three types of products: A, [(CO)5M]2X-R containing trigonally planar coordinated X; C, [(CO)5M]3X-R containing coordinated metallacyclic ligands; B, [xxx] D, [(CO)5M]n (R)X = X (R) (n = 0, 1, 2, 3). The relation between these species, especially the one based on the valence tautomerism between A und B, is experimentally verified. Preparative, spectroscopic and X-Ray-structural results reveal a consistent picture of the relevant chemistry.

Der Chlorarsinidenkomplex CLAs[(CO)5Cr]2 (1) reagiert mit Ammoniumsalzen der Halogenid- und Pseudohalogenid-Ionen Cl−, Br−, I−, CN−, N3 und SCN− unter Bildung von anionischen 1 : 1-Addukten. Darstellung und Eigenschaften aller Komplexe sowie die an der Verbindung HPy+ (CL2As[(CO)5Cr]2)− durch Rontgenstrukturanalyse belegte Konstitution werden beschrieben.

As 2 est donneur de 4 electrons dans [Cp(CO) 2 M] 2 As 2 (M=Mo, W), de 6 electrons dans [Cp(CO) 2 M] 2 As 2 Cr(CO) 5 (M=Mo, W) ou de 8 electrons dans [Cp(CO) 2 M] 2 As 2 [Cr(CO) 5 ] 2 (M=Mo, W). Structures

The chloroarsinidene complexes (CO)5Cr⎓As(Cl)⎓Cr(CO)5 (I) and Cp(CO)2-Mn⎓As(Cl)⎓Mn(CO)2Cp (III) react with R3Al (R ⎓ alkyl, aryl) to give (CO)5Cr⎓As(R)⎓Cr(CO)5 (II) and Cp(CO)2Mn⎓As(R)⎓Mn(CO)2Cp (IV), respectively. The alkylarsinidene complexes obtained in this way for the first time are intensely coloured crystalline compounds, which contain trigonally planar coordinated arsenic(I) as shown by X-ray analysis of i-C4H9As[Cr(CO)5]2 (IIb). Reaction of Na2M2(CO)10 with RAsCl2 (R ⎓ alkyl; M ⎓ Cr, W) is another route to the alkylarsinidene compounds RAs[M(CO)5]2. Similarly AsCl3 and Na2Cr2(CO)10 react to give the chloroarsinidene complex I. The heterometallic arsinidene complex (CO)5Cr⎓As(Cl)⎓Mn(CO)2Cp (VIII) is obtained by thermally induced comproportionation from I and III. Like other chloroarsinidene complexes it reacts with tropolone to give an arsenic(I) chelate (IXa) stabilized by complexation. The structure of IXa has been determined by X-ray methods. In the presence of a base reaction of VIII with water leads to [(CO)5Cr] [Cp(CO)2Mn]AsOAs[Mn(CO)2Cp] [Cr(CO)5] (Xa). Under similar conditions I and III give analogous homometallic derivatives of As2O, an arsenic(I) oxide, not known in the free state. An X-ray analysis of [MeCp(CO)2Mn]2AsOAs[Mn(CO)2CpMe]2 (Xb) shows that in compounds X both arsenic atoms have a trigonal planar configuration. The arsenic atoms in X are thus coordinatively unsaturated and will add Lewis bases to give adducts like [(CO)5Cr]2As(PPh3)OAs(PPh3)[Cr(CO)5]2 (XI).

In (LnM)2X-Hal compounds which contain a trigonally planar coordinated bridging element (X = P, As, Sb) stabilized by two 16-electron LnM fragments the halogen may be substituted by monovalent organometallic groups. In the resulting molecules the bridging X atoms are coordinated to three metal atoms in a trigonal planar fashion. The syntheses and properties of 12 species of this type (I–IX) are described. The reaction of Na2W2(CO)10 with XCl4 (X = Ge, Sn) leads to [(Co)5W]3(μ3-X) compounds containing trigonally planar coordinated Ge (X) and Sn (XI), respectively. The trigonal planar coordination of the Main Group elements X is confirmed by eight X-ray analyses.

Die Chlorfunktion im Arsiniden-Komplex ClAs[(CO)5Cr]2 (1a) kann durch Umsetzung mit Nucleophilen wie Halogenid-Ionen, Alkoholen oder S- und Se-Homologen gegen andere Halogene sowie RO-, RS- und RSe-Gruppen ausgetauscht werden. Substitution durch C6H6 gelingt mit BiPh3 als Phenylierungsmittel, Chlor-Brom-Austausch erfolgt bei der Reaktion von 1a mit BBr3. ClAs[η5-C5H5(CO)2Mn]2 (2a) reagiert ahnlich. Fur die Synthese von Phenylarsiniden-Komplexen stehen neben der Halogensubstitution eine Reihe weiterer Synthesewege zur Verfugung. Die Elektronenspektren der intensiv farbigen Arsiniden-Komplexe werden unter Berucksichtigung der Elektronenspektren von Phosphiniden- und Stibiniden-Komplexen diskutiert. - Die Strukturchemie von Arsiniden-komplexen, die trigonal-planar koordiniertes Arsen(+ 1) enthalten, wird anhand von rontgenstrukturanalytischen Ergebnissen an 1a und 2a sowie PhAs[(CO)5Cr]2 (1d) und PhAs[η5-C5H5(CO)2Mn]2 (2c) besprochen. Arsinidene Complexes: Syntheses, Substitution Reactions, Spectra and Structures of X As[(CO)5Cr]2 and XAs[η5-C5H5(CO)2Mn]2 (X = Aryl, Halogen, RE where E = O, S, Se) Within the arsinidene complex ClAs[(CO)5Cr]2 (1a) the chlorine function may be substituted by reaction with nucleophiles such as halide ions, alcohols or their S- and Se- homologues by other halogens, or RO- RS- and RSe-groups, respectively. Phenyl substitution occurs with BiPh3 as the phenylating agent. Chlorine-bromine exchange is observed upon reaction of 1a with BBr3. ClAs[η5-C5H5(CO)2Mn]2 behaves similarly to 1a. For the synthesis of phenylarsinidene complexes other methods in addition to halogen substitution have been developed. The electronic spectra of the deeply colored arsinidene complexes are discussed in context with the electronic spectra of the deeply colored arsinidene complexes are discussed in context with the electronic spectra of phosphinidene and stibinidene complexes. – The structural chemistry of arsinidene complexes, which contain trigonally planar coordinated arsenic (+ 1), is exemplified by the X-ray results obtained from 1a and 2a as well as PhAs[(CO)5Cr]2 (1d) and PhAs[η5-C5H5(CO)2Mn]2 (2c).

Komplexe [(CO)5M]2XR (XAs, Sb), in denen die Sextettliganden durch π-Wechselwirkung mit den 16-Elektronenfragmenten (CO)5M (MCr, Mo, W) stabilisiert sind, bilden mit Lewisbasen |B stabile Addukte [(CO)5M]2X(R)B. Die Adduktbildung kann zum Nachweis des intermediaren Auftretens von nicht isolierbaren Arsiniden- und Stibiniden-Komplexen [(CO)5M]2XR eingesetzt werden. Auf diese Weise gelingt es zu zeigen, das bei Reaktionen von Na2M2(CO)10 mit RXCl2 stets Arsiniden- bzw. Stibiniden-Komplexe gebildet werden, die sich als stabile Addukte mit Lewisbasen wie PR3, P(OMe)3, Thioharnstoff, RNH2 und THF isolieren lassen. Synthese und Eigenschaften solcher Addukte werden besprochen. Ihr Bau wird durch Kristallstrukturen von 1i, 3b und 5a belegt. Trapping of Arsinidene and Stibinidene Intermediates: Addition of Lewis Bases to [(CO)5M]2XR (XAs, Sb; MCr, Mo, W) The compounds [(CO)5M]2XR (XAs, Sb) which contain the sextett ligand stabilised by π-interaction with the 16 electron fragments (CO)5M (MCr, Mo, W) form stable adducts [(CO)5M]2X(R)B with lewis bases |B. The formation of adducts may be used to demonstrate the intermediate existence of non-isolable arsinidene and stibinidene complexes [(CO)5M]2XR. By this method it is shown that Na2M2 (CO)10 reacts with RXCl2 to give arsinidene and stibinidene complexes in any case. These compounds may be isolated as stable adducts by lewis bases such as PR3, P(OMe)3, thiourea, RNH2, and THF. Syntheses and properties of adducts of this type are discussed here. The structure is documented by X-ray analyses of 1i, 3b, and 5a.

Die erstmalige Synthese von Verbindungen, in denen alle funf Valenzelektronen eines μ3-verbruckenden Arsenatoms in die Bindung zu drei Metall-Ligand-Fragmenten einbezogen sind, gelingt durch Umsetzung von Arsiniden-Komplexen ClAs[MLn]2 (MLn = Cr(CO)5, Mn(CO)2(η5-CH3C5H4)) mit η5-C5H5(CO)3M′− (M′ = Mo, W). In den unter Substitution der Chlorfunktion und Ausbildung einer M′M-Bindung unter CO-Abspaltung entstandenen Komplexen 3, (3a, M′ = Mo, MLn = Mn(CO)2(η5-CH3C5H4); 3b, M′ = Mo, MLn = Cr(CO)5; 3c, M′ = W, MLn = Cr(CO)5) besitzt das Arsen kein freies Elektronenpaar mehr. Es ist daher trigonal planar koordiniert; sein Elektronendefizit wird, wie in Arsiniden-Komplexen, durch π-Bindungsanteile in den Metall-Arsen-Bindungen ausgeglichen. Rontgenstrukturanalysen fur 3a–c belegen dies. Reaction of Arsinidene Complexes: Arsenic Atoms as Trigonally Planar Coordinated Bridging Elements within Trinuclear Metal Complexes The synthesis of compounds in which all five valence electrons of a μ3-bridging arsenic atom are involved in bonding to three metal ligand fragments is achieved for the first time by the reaction of arsinidene complexes ClAs[MLn]2 (MLn = Cr(CO)5, Mn(CO)2(η5-CH3C5H4)) with η5-C5H5(CO)3Ml′− (M′ = Mo, W); chlorine substitution and MM′ bond formation with accompanying loss of one carbonyl group leads to the complexes 3, (3a, M′ = Mo, MLn = Mn(CO)2(η5-CH3C5H4); 3b, M′ = Mo, MLn = Cr(CO)5; 3c, M′ = W, MLn = Cr(CO)5). In compounds 3 there is no lone pair left at the μ3-arsenic atom which therefore shows trigonal planar coordination. The electron deficiency at the arsenic atom is compensated for by metal-arsenic η-bonding in a manner similar to the bonding situation in arsinidene complexes. X-ray analyses for 3a–c confirm this statement.

Reactions of Fe 2 (CO) 9 with L n MPHal 3 (L n M = 16-electron fragment: Cp(CO) 2 Mn, (CO) 5 Cr, (CO) 5 Mo, (CO) 5 W) yield clusters of the type F 3 (CO) 9 (μ 4 -P) 2 (ML n ) 2 (II). Compounds II contain the trigonal bipyramidal cluster framework Fe 3 (CO) 9 (μ 3 -P) 2 , the basis of which is a closed triangle formed by three Fe(CO) 3 units; the apical positions of the trigonal bipyramid are occupied by phosphorus atoms. Each of the capping phosphorus atoms binds an additional ML n fragment. Compounds of type II are also obtained from Fe 2 (CO) 6 (μ 3 -P) 2 (ML n ) 2 (I) by formal addition of an Fe(CO) 3 group. A further general synthetic approach to clusters Fe 3 (CO) 9 (μ 4 -X) 2 (ML n ) 2 (X = P, As, Sb) is the reaction of halo-phosphinidene, arsinidene or stibinidene complexes, (L n M) 2 XHal (X = P, As, Sb) with Na 2 Fe(CO) 4 . Similar procedures are used for the construction of compounds III and IV. Complexes III contain phosphorus as a μ 4 -spiro centre; compounds IV contain metallacyclic phosphanes (CO) 4 FeP(R)Fe (CO) 4 as ligands. From (CO) 5 CrPBr 3 and Fe 2 (CO) 9 the cluster Fe 2 (CO) 7 (PP)[Cr(CO) 5 ] 2 (V) is obtained in which a diphosphorus unit is side-on and end-on coordinated as an eight-electron ligand. The identity of the new compounds is documented by analytic and spectroscopic data as well as by X-ray-structure analyses of seven compounds.

Arsinidenkomplexe (III) entstehen besonders einfach durch Reaktion von (I) mit den Arsinen (II).

The complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 411. DOI:10.1002/anie.198204110