O,O′‐Diethylthiocarbonat setzt sich mit Bis‐(tetrahydrofuran)lithium‐bis(trimethylsilyl)phosphanid in 1,2‐Dimethoxyethan unterhalb 0°C zu Ethoxy‐trimethylsilan und Tris(1,2‐dimethoxyethan‐O,O′)lithium‐2λ3‐phosphaethinylsulfanid – [P≡CS]−[Li(dme)3]+ – (1a) um. Das als dunkelrote, konzentrierte Lösung erhaltene λ3‐Phosphaalkin 1 entsteht neben Bis(trimethylsilyl)sulfan bzw. Kohlenstoffoxidsulfid auch bei den Umsetzungen von Kohlenstoffdisulfid mit Bis(tetrahydrofuran)lithium‐bis(trimethylsilyl)phosphanid oder dem homologen Lithoxy‐methylidinphosphan P≡COLi (2) [1]. Das IR‐Spektrum weist die für eine P≡C‐ und CS‐Valenzschwingung charakteristischen Absorptionen bei 1762 und 747 cm−1 auf; die NMR‐Parameter {δ(31P) − 121,3; δ(13C) 190,8 ppm; 1JCP 18,2 Hz} gleichen mehr den Werten der Diorganylamino‐2λ3‐phosphaalkine als des Bis(1,2‐dimethoxyethan‐O,O′)‐lithoxy‐methylidinphosphans (2a). Nach den Ergebnissen einer Röntgenstrukturanalyse (P21/c; a = 1192,6(16); b = 1239,1(19); c = 1414,8(26) pm; β = 105,91(13)° bei −100 ± 3°C; Z = 4 Formeleinheiten; wR = 0,064) an blaßgelben, aus einem Ansatz mit O,O′‐Diethylthiocarbonat isolierten Kristallen (Schmp. + 16°C) liegen im Festkörper getrennte [P≡CS]−‐ und [Li(dme)3]+‐Ionen vor. Charakteristische Bindungslängen und ‐winkel sind: P≡C 155,5(11); CS 162,0(11); LiO 206,4(17) bis 220,3(20) pm; P≡CS 178,9(7)°.

Os(SiCl3)Cl(CO)(PPh3)2 is prepared by treatment of OsPhCl(CO)(PPh3)2 with excess HSiCl3 and serves in turn as the starting material for the syntheses of three more five-coordinate silyl complexes Os(SiR3)Cl(CO)(PPh3)2 (R = F, OH, Me) via substitution of the chloride groups on silicon. All four compounds were fully characterized, including a single-crystal solid-state structure of each derivative. Carbonyl stretching frequencies decrease and Os−Si bond lengths increase as R changes in the order from F to Cl to OH to Me. Ab initio calculations were performed on the model complexes Os(SiR3)Cl(CO)(PH3)2 (R = F, Cl, OH, Me) to explain the trends observed in the IR and X-ray studies, and the importance of the π-acceptor capacities of the silyl groups are discussed.

(1: M = Ru, R = Itortion along the 0s-Si axis from an idealised tetrahedral geometry for the central OsSiP, heavy-atom skeleton. The structure can be described as two face-shared octahedra, one based on osmium (OsH,P,) Keywords ab initio calculations hydrides osmium * ruthenium silicon and the other based on silicon (SiH,N,). Studies of the bonding situation in 2a reveal that the N-pyrrolyl substituents have a marked shortening cffect on the osmium-silicon distance (229.3 (3) pm) and that each of the three hydride ligands participates in partial three-centre bonding involving osmium, silicon and hydrogen.'H, I 3 C , 2ySi and 31P N M R spectra were used to determine the solution structures of complexes 1 and 2a.

Professor Josef Goubeau in memoriamInhaltsu È bersicht. Basefreies Tris(trimethylsilyl)methyl-Lithium, Tsi±Li, reagiert mit den Trihalogeniden der Erdmetalle (MHal 3 mit M = Al, Ga, In und Hal = Cl, Br, I) prima È r unter Bildung der Metallate [Tsi±MHal 3 ]Li. Vor allem mit den schwereren Halogeniden von Ga und In findet aber mit u È berschu È ssigem Tsi±Li zusa È tzlich zur simplen Metathese gleichzeitig auch eine Methylierung statt, die in unterschiedlichem Maûe die Mono-und Dimethylverbindungen Tsi±M(Me)Hal (M = Ga, In; Hal = I), Tsi±MMe 2 (M = Ga) bzw. das Bis-(trisyl)derivat (Tsi) 2 InMe sowie stets als Nebenprodukt noch 1,3-Disilacyclobutan ergibt. Durch mehrma-lige, fraktionierende Kristallisationen oder Sublimationen konnten Vertreter dieser Verbindungstypen aus den Reaktionsmischungen isoliert und mit spektroskopischen Methoden ( 1 H, 13 C, 29 Si-NMR; IR, Raman) sowie zum Teil ro È ntgenographisch charakterisiert werden. FeCl 3 reagiert mit Tsi±Li (Verha È ltnis 1 : 3) in Toluol bei 55±60°C unter Reduktion, wobei rotviolettes Fe(Tsi) 2 , 1,1,1-Tris(trimethylsilyl)-2-phenylethan und geringe Mengen an Tsi±Cl gebildet werden. Fe(Tsi) 2 ist monomer, kristallisiert in der monoklinen Raumgruppe C2/c und hat ein lineares C±Fe±C-Skelett mit Fe±C-Bindungsabsta È nden von 204,5(4) pm.Abstract. Base-free tris(trimethylsilyl)methyl Lithium, Tsi±Li, reacts with the earth-metal trihalogenides (MHal 3 with M = Al, Ga, In and Hal = Cl, Br, I) primarily to give the metallates [Tsi±MHal 3 ]Li. Simultaneous to this simple metathesis a methylation also takes place, mainly with heavier halogenides of Ga and In with excess Tsi±Li, forming the mono and dimethyl compounds Tsi±M(Me)Hal (M = Ga, In; Hal = I), Tsi±MMe 2 (M = Ga), and the bis(trisyl)derivative (Tsi) 2 InMe, respectively and the main by-product 1,3-disilacyclobutane. Representatives of each type of compound have been isolated by fractionating crystallizations or subli-mations and characterized by spectroscopic methods ( 1 H, 13 C, 29 Si NMR, IR, Raman) and X-ray elucidations. Reduction takes place, when FeCl 3 reacts with Tsi±Li (1 : 3 ratio) in toluene at 55±60°C, yielding red-violet Fe(Tsi) 2 , 1,1,1-tris-(trimethylsilyl)-2-phenyl ethane and low amounts of Tsi±Cl. Fe(Tsi) 2 is monomeric, crystallizes in the monoclinic space group C2/c and consists of a linear C±Fe±C skeleton with d(Fe±C) of 204,5(4) pm.

A range of λ 3 -phosphaalkynes PtC-R (R ) F, Cl, O -, OLi, OH, OSiMe 3 , S -, SLi, SH, Me, SiMe 3 , H) 1 has been geometry-optimized at the HF, MP2, and CCSD(T) level of theory. Vibrational frequencies as well as 31 P and 13 C NMR chemical shifts were calculated and compared to experimental values of the large variety of λ 3 -phosphaalkynes prepared over several years via differing synthetic routes. With a few obvious exceptions, a good agreement of calculated and experimental parameters was found. This also opens up the possibility to make predictions on spectroscopic data of compounds not yet synthesized or fully characterized, e.g., PCOSiMe 3 and PCSH. The bonding situation especially of the negatively charged species PtC-O -and PtC-S -was studied via NBO analyses to determine the degree of phosphaalkyne and heterocumulene contributions to the mesomeric anions.