Wil P. Bosman

Heterometallic Pt-Au complexes with μ-3 S bridging. Syntheses and structures of Pt2 (PPh3)4(μ-SAuCl)2·2CH2Cl2 and Pt2(PPh3)4−(μ-S)(μ-SAuPPh3)NO3·0.5H2O

Abstract From Pt 2 (PPh 3 ) 4 (μ- S ) 2 ( I ) three heterometallic complexes can be prepared: Pt 2 (PPh 3 ) 4 (μ-SAuCl) 2 ( II ), (Pt 2 (PPh 3 ) 4 (μ-SAuPPh 3 ) 2 2+ ( III ) and Pt 2 (PPh 3 ) 4 - (μ-S)(μ-SAuPPh 3 ) + ( IV ). Their preparation and properties are described. The crystal and molecular structures of II and the nitrate of IV has been investigated by X-ray diffraction analysis. II crystallizes in the monoclinic space group P 2 1 / n , a = 18.359(2) b = 13.947(2), c = 14.588(2) A, β = 100.982(7)°, V = 3666.9 A 3 , M r = 2138.28, Z = 2, D c = 1.94 Mg/m 3 . Mo Kα radiation (graphite crystal monochromator, λ = 0.71069 A, μ(Mo Kλ)= 85.13 cm −1 , F (000) = 2032, T = 293 K. Final conventional R -factor = 0.039, Rw = 0.050 for 5084 unique reflections and 155 variables. IV crystallizes in the triclinic space group P 1 , a = 14.605(1), b = 15.989(2), c = 18.005(2) A, α = 101.144(8)°, β = 100.773(7)°, γ = 91.201(2)°, V = 4045.4 A 3 , M r = 2033.75, Z = 2, D c = 1.66 Mg/m 3 . Cu Kα radiation (graphite crystal monochromator, λ = 1.5418 A), μ(Cu Kα) = 116.45 cm −1 , F (000) = 1986, T = 293 K. Final conventional R -factor = 0.039 Rw = 0.051 for 8631 unique reflections and 297 variables. Both the structures were solved using SHELX84 and DIRDIF. The hinged square planar geometry of the parent I is kept in IV , where AuPPh 3 is bonded to one of the bridging S atoms. In II both bridging S atoms are bonded to AuCl and the hinging geometry is transformed into a nearly planar P 2 PtS 2 PtP 2 frame with the SAuCl vectors nearly perpendicular to it, one on each side of that plane. There are indications for weak Auue5f8Pt bonding interactions. In IV and II the three-coordinated S-atoms have bond angles of about 90°. The structure of III is supported to be similar to II . Some reactions and interconversions of II , III and IV are described.

The cleavage of carbonsulfur and carbonnitrogen bonds leading to rhodiumthiocarboxamido complexes

Abstract The cleavage of a Cue5f8S bond in methyl ( N,N -dimethyl)dithiocarbamate, MeSC(S)NMe 2 , by RhCl(PPh 3 ) 3 results in the formation of the methylsulfidothiocarboxamido complex RhCl(SMe)(SCNMe 2 )(PPh 3 ) 2 · C 6 H 6 . The MeS group in this complex reacts with CS 2 to form the trithiocarbonato-thiocarboxamido complex RhCl(S 2s CSM)(SCNMe 2 )PPh 3 . Cleavage of the Cue5f8S bond in tetramethylthiurammonosulfide Me 2 NC(S)SC(S)NMe 2 yields the dithiocarbamato-thiocarboxamido complex RhCl(S 2 CNMe 2 )(SCNMe 2 )PPh 3 . The analogous Cue5f8N bond breaking in 1,1,5,5-tetramethyl-3-phenyl-dithiobiuret, Me 2 NC(S)N(Ph)C(S)NMe 2 , results in the formation of RhCl[N(Ph)C(S)NMe 2 ](SCNMe 2 )PPh 3 . The crystal structure determination of chloro( N,N -dimethyldithiocarbamato)( N,N dimethylthiocarboxamido)triphenylphosphinerhodium(III) - chloroform reveals that the thiocarboxamido group is coordinated to Rh via a very short Rhue5f8C bond (1.895 A) and a much weaker Rhue5f8S (2.432 A) interaction.

Reactions of gold–phosphine cluster compounds. Preparation and X-ray structure determination of octakis(triphenylphosphine)octa-gold bis(hexafluorophosphate)

[Au9L8]3+(L = PPh3) reacts with L to form [Au8L8]2+ and [AuL2]+; preliminary X-ray structural results are reported for [Au8L8][PF6]2.2CH2Cl2(1).

Monosubstituted nitrogen donors as ligands in cyclopentadienyliron complexes: synthesis, reactivity, ligand properties, and crystal structure of [C5H5Fe(CO)2(C5H5N)]SbF6

Abstract Cationic complexes [C 5 H 5 Fe(CO) 2 )]BF 4 , with L a monosubstituted nitrile, RCN, or a pyridine C 5 H 4 NR′ have been prepared by oxidative cleavage of [C 5 H 5 Fe(CO) 2 ] 2 with [(C 5 H 5 ) 2 Fe]BF 4 in the presence of an excess of L. The coordinated nitriles act as relatively weak donors and the donor strength dependence or R as observed by NMR and IR spectroscopy is in good agreement with Tafts inductive factor δ* for the uncoordinated ligand. These constants correlate roughly with the charge on the nitrogen atom of the uncoordinated RCN ligand as found by AM1 calculations. For the stronger donor ligands C 5 H 4 NR′ there is no overall dependence of their donor strength, but for systems with substituents in the same ring position there is a correlation of the δ 13 C CO shift of the complex with the p K a value of the uncoordinated pyridine ligand. The lability of the coordinated nitrile has been demonstrated by ligand replacement with anionic nucleophiles (X − = I and CN) or Group Vb donor ligands ER 3 (E = P, R = C 6 H 5 , OCH 3 , OC 6 H 5 ; E = As, Sb, R = C 6 H 5 ) to give the related C 5 H 5 Fe(CO) 2 X and [C 5 H 5 Fe(CO) 2 (ER 3 )]BF 4 complexes in high yields. Related substitutions are only found with X − in the pyridine series. When L = C 5 H 4 NR′ with R′ = 3-4-CN or 4-N(CH 3 ) 2 , a nonseparable mixture of isomeric complexes involving coordination of the pyridine-nitrogen or of the pyridine substituent R′ are obtained. The observed ratio between these isomers depends on the p K a value of the uncoordinated pyridine and on the reaction conditions.

Synthesis and characterization of [Pt(CN)(AuCN)(AuPPh3)8](NO3) and Pt(CO)(AuPPh3)6(AuCN)2. Crystal structure of [Pt(CN)(AuCN)(AuPPh3)8] (NO3)

Abstract Pt(CN)(AuCN)(AuPPh3)8+ (1) can be prepared from Pt(AuPPh3)82+ (2) by an oxidative addition reaction with Au(CN)2−. The CO in Pt(CO)(Au- PPh3)82+ cannot be replaced with CN−, but in a slow process two PPh3 are replaced, forming Pt(CO)(Au- CN)2(AuPPh3)6 (3). The compounds are characterized by 31P, 13C and 195Pt NMR, FAB-MS and IR measurements. The structure of Pt(CN)(AuCN)- (AuPPh3)8(NO3) is determined by X-ray diffraction (monoclinic, space group P21/n, a = 17.269(20), b = 29.638(17), c = 27.88(3) A, β = 93.95(14)°, V = 14233 A3, Z = 4, the residuals are R = 0.063 and Rw = 0.090 for 5965 observed reflections and 467 variables Cu Kα radiation). In the metal cluster the central Pt atom is surrounded by eight Au atoms and one CN ligand in a spheroidal structure similar to that of Pt(CO)(AgNO3)(AuPPh3)82+.

Bidentate, monodentate and bridging thiocarboxamido complexes of rhodium and iridium; the x-ray structure determination of [Ir(η2-SCNMe2)2(CO)(PPh3)]+ BF4−

Abstract Me 2 NC(S)Cl reacts with “IrCl(PPh 3 ) 2 ”, IrCl(CO)(PPh 3 ) 2 and IrH(CO)(PPh 3 3 , to give cis - and trans -IrCl 2 (η 2 -SCNMe 2 )(PPh 3 ) 2 , trans -[IrCl(η 2 -SCNMe 2 )(CO)(PPh 3 ) 2 ] + Cl − and trans -[IrH(η 2 -SCNMe 2 )(CO)(PPh 3 ) 2 ] + Cl − , respectively (with cis and trans referring to the relative position of the PPh 3 groups). Dehydrohalogenation of trans -[IrH(η 2 -SCNMe 2 )(CO)(PPh 3 ) 2 ] + Cl − by Et 3 N results in trans -Ir(η 1 -SCNMe 2 )(CO)(PPh 3 ) 2 and the dimeric [Ir(μ-SCNMe 2 )(CO)(PPh 3 )] 2 . Dehydrohalogenation of trans -[IrH(η 2 -SCNMe 2 )(CO)(PPh 3 ) 2 ] + Cl − in the presence of Me 2 NC(S)CI gives the bis(η 2 -thiocarboxamido) complex [Ir(η 2 -SCNMe 2 ) 2 (CO) (PPh 3 ) + Cl − . In the reaction of Me 2 NC(S)CI with RhH(CO)(PPh 3 ) 3 displacement of CO occurs and RhCl(η 2 -SCNMe 2 ) 2 (PPh 3 ) 2 is formed. This complex can also be prepared from Me 2 NC(S)Cl and RhH(PPh 3 ) 4 . The X-ray structure analysis of [Ir(η 2 -SCNMe 2 ) 2 (CO)(PPh 3 )] + BF 4 − shows both SCNMe 2 ligands to be planar and coordinated via C and S, with bond distances and angles comparable to those in other η 2 -SCNMe 2 complexes. As the Cue5f8Irue5f8S angles within both IrSCNMe 2 , units are small (43°), the coordination geometry around the iridium is distorted octahedral.

Synthesis of a new heteronuclear gold–cobalt cluster. Preparation and X-ray structure determination of tetrakis (triphenylphosphine)-bis(tetracarbonylcobalt)hexagold

The reaction of [AU8L7]2+(L = PPh3) with an excess of Li[Co(CO)4] in tetrahydrofuran results in the formation of Au6L4[Co(CO)4]2, the structure of which has been determined by X-ray crystallography.

Two silicon-bridged cyclopentadienyl Fe2S4 cluster units connected through an Fe(III)S6 unit. Crystal and molecular structure of [((CH3)2SiCp′2)2Fe5(μ3-S2)2(μ4-S2)2(μ4-S4)]FeCl4

Abstract The reaction of (CH 3 ) 2 Si[Cp′Fe(CO) 2 ] 2 with elemental sulfur in refluxing toluene resulted in the formation of two new iron-sulfur cluster compounds. Prolonged crystallisation from CH 2 Cl 2 -hexane mixtures of one of these compounds resulted in crystals of the title compound. An X-ray diffraction study revealed that two (CH 3 ) 2 SiCp′ 2 Fe 2 units are connected to a central Fe(III) ion via four disulfido ligands and a tetrasulfido ligand. This iron atom is octahedrally coordinated by six sulfur atoms. Of the six Fe(III)ue5f8S distances four are close to 2.30 A and the other two are about 2.20 A. In both the (Ch 3 ) 2 SiCp′ 2 Fe 2 units each iron atom is coordinated to three sulfur atoms and one Cp ring. This results in twelve Feue5f8S distances: six of them are in a narrow range from 2.165 to 2.184 A, whereas the other six vary from 2.240 to 2.286 A. The Feue5f8Fe distances are 2.561 and 2.581 A. The Sue5f8S distances range from 2.041 to 2.073 A. The Feue5f8Cl distances in the FeCl 4 − ion, centred around 2.16 A, show the presence of Fe(III) in this ion.

Synthesis and X-ray crystal structure determination of the cationic gold cluster compound [Au8(PPh3)7](NO3)2

The reaction of [Au8L8](NO3)2(L = PPh3) with the phosphine scavenger [RhCl(C8H14)2]2 yields [Au8L7]-(NO3)2, X-ray analysis of which reveals the Au skeleton to be a fragment of the centred icosahedron; the cluster to be a fragment; the cluster is an intermediate in the reactions of [Au9L8]3+, and its 197 Au Mossbauer spectrum lacks, like that of [Au9L8]3+, a separate resonance for the central Au atom.

Stereo- und regioselektive Mehrfachadditionen an komplexgebundenes Cyclooctatetraen in [CpFe(η6-Cot)]+

Abstract The cationic complex [CpFe(η 6 -Cot)] + (Cot = cyclooctatetraene) 1 has been shown to be very suitable for high yield nucleophilic additions. The nucleophiles Nu − (Nu ue5fb HC(CO 2 Me) 2 , 2a ; HC(CO 2 Et) 2 , 2b ; NMe 2 , 2c ; H, 2d ) add exclusively at the Cot ring, and stereoselectively in exo position with respect to the metal centre. Subsequently, the electrophilic addition of H + to the neutral compound CpFe(2-6-η-C 8 H 8 - 1- exo -Nu) generates the new cationic product [CpFe(2-7-η-C 8 H 9 -1- exo -Nu)] + ( 4 ), which can add a second nucleophile revealing an exo , exo -1,7-disubstituted cyclooctadienyl ligand. The X-ray structure analysis of the methyl malonate compound 2a (space group P 2 1 / c , a = 19.083(1) a, b = 7.9169(5) A, c = 11.278(2) A, β = 106.77(1)°, R merge = 0.062) shows the η 2–6 coordination mode of the cyclo -C 8 -ligand, the exo -position of the Nu-substituent, and the endo-position of the hydrogen atom at the sp 3 carbon atom of the C 8 -ring confirmed by residual electron density. The cyclo -C 8 -ring is bent, and the angle between the two best planes, which are defined by C-7, C-8, C-1 and C-2—C-6, amounts to 122.7°.