Substitution of two chlorine atoms in 1,2-bis(dichloroboryl)ethane with diisopropylamine yields 1,2-bis(chlorodiisopropylaminoboryl)ethane (4), which is reacted with Na/K alloy to give 1,2-bis(diisopropylamino)-1,2-diboretane (5) in 91% yield. 5 crystallizes in the space group P 21/c with the lattice constants a = 6.116(1), b = 16.658(5), c = 17.577(4) Å, β = 99.49(2)°.

Sandwich und Triple-Decker Complexes of 1.4-Diboracyclohexadienes Starting with 1.4-Dibora-2-cyclohexene Derivatives Reactions of 1,4-dibora-2-cyclohexene derivatives 1 with tran-dimeric carbonyl (cyclopentadienyl) complexes of nickel and sition-metal complex fragments yield the complexes of 1,4-iron, respectively. The bis(methallylnicke1) tripledecker 9a is dibora-2,5-cyclohexadienes 2 by dehydrogenation. The tetra-obtained as a mixture of cisltrans isomers, l a and [(C,H,) Ergebnisse und DiskussionSandwichkomplexe 2c2) und 2d7) reagieren mit Metallcarbonyl-Verbindungen unter Bildung der Carbonyl-Komplexe 4c,d und 5c,d. Aus (CH3CN)3Cr(CO)3 und l a entsteht bei 25°C mit 45% Ausbeute der gelbe Tetracarbonyl-Komplex 4a, der sich im Licht schnell zersetzt. Die ebenfalls lichtempfindlichen gelben o l e Sa, b werden durch Umsetzung von la, b mit Fez-(CO), in THF bei 50°C erhalten. Weder durch Photolyse noch durch Erhitzen von 5a, b in Toluol gelang es, die Carbonyl-Gruppen unter Bildung von 6a, b zu substituieren. Orangerotes 6b bildet sich aus 1 b und Bis(toluo1)eisen. Bei der Chromatographie der Reaktionslosung (Silicagel/Petrolether) findet teilweise Zersetzung statt, die Ausbeute an 6b betragt nur 4%. 6Die "B-NMR-Werte von 4a, 5a, b und 6b liegen zwischen 6 = 22 und 28 und bestiitigen die monofaciale KoordinaChem.

1991 organo-boron compounds, nonmetal heterocycles organo-boron compounds, nonmetal heterocycles S 0047 15 -210 Redox Reactions with Iodoboranes. Part 18. Synthesis and Properties of 1,4-Diboracyclohex-2-ene Derivatives. -The title compounds (V) are prepared and their electrochemical properties as well as the ESR parameters of their anions are reported. The X-ray structures of the 16 valence electron complexes (VIa) ( modification 1: space group P21/c, Z = 4; modification 2: P1, Z = 4) and (VIb) (Pbnm, Z = 4) are determined. -(UHM, J.-K.; HU, D.; ZENNECK, U.; PRITZKOW, H.; SIEBERT, W.; Taehan

C 2 B 9 H 11 )Mo(CO) 3 ] 2 PPN 2 (2·PPN 2 ), a new precursor for the oxidative decarbonylation reaction, was synthesized in high yield by the one-electron oxidation reaction of [(C 2 B 9 H 11 )Mo(CO) 3 ]PPN 2 . 2·PPN2 was structurally characterized, showing a dimeric nature with long (3.321 Å) Mo-Mo bonding. Reaction of 2·PPN2 with sulfur gave the completely decarbonylated product [(C 2 B 9 H 11 )Mo(µ-S)(S)] 2 PPN 2 (3·PPN 2 ). The ligand substitution of the terminal sulfur ligands in 3·PPN2 to oxygen ligands was carried out with the use of PhIO to give [(C 2 B 9 H 11 )Mo(µ-S)(O)] 2 PPN 2 (4·PPN 2 ). The structures of 3·PPN2 and 4·PPN2 were also studied.

Reaction between Cl2AlCH2CH2AlCl2 and BCl3 leads to Cl2BCH2CH2BCl2, in which halogen exchange is achieved by Bl3 to yield I2BCH2CH2BI2 (5). Redox reaction between butyne-2 and 5 results in the formation of 1,4-diiodo-2,3-dimethyl-1,4-diboracyclohexene-2 (1a) and iodine. Methylation of 1 a with AlMe3 leads to the title compound 1 d , established by 1H, 11B, 13C NMR. Heating of 1 d in toluene at 160 °C in a sealed tube results in an intramolecular isomerization to give 1,2,3,4,5-pentamethyl-2,3-dihydro-1,3-diborole (2d) in 90% yield.