An das 16-Elektronen-System [Re(CO)J + [z. B. als (0C)?ReFBF3] lassen sich zahlreiche ,,harte" und ,,weiche" Nucleophile addieren". Die metallorganische Lewis-Saure Re(CO):, die bei den stets unter sehr milden Bedingungen ablaufenden Reaktionen intakt bleibt und im IR-Spektrum aufgrund des typischen CO-Musters leicht verfolgt werden kann, erscheint besonders geeignet, um als Sonde das Verhalten verschiedenartiger -auch ambidenter -Liganden zu priifen. Im folgenden berichten wir iiber Reaktionen von Pentacarbonyl(tetrafluoroborato)rhenium mit neutralen und anionischen organischen Cyanverbindungen.

No abstract

A large series of metal carbonyl complexes with N -bonded anions of various cyclic imidates (X-) has been prepared: [M(CO)5X]-, [M(CO)4(PPh3)X], [M(CO)3(en)X]- (M = Cr, Mo, W), Re(CO)5X , [π-CH3C5H4Mn(CO)2X]-, [Mn(CO)4X2]-. Also pyromellitdiimidate and cyclopentanebis(dicarboximidate) bridged complexes [(OC)5MXM(CO)5]2- (M = Cr, Mo, W) and the dicyanamide complex [π-(C5H5)Mn(CO)2NCNCN]- have been obtained. Reactions at the coordinated imidate ligands and the spectroscopic data of the complexes are reported.

fests itself in the different values of 'J(P'P3) and 'J(P3Ps) and, in particular, in the large coupling constants 'J(PSP7) and 'J(P'P") caused by the resulting folding of the fourmembered ring; the five-membered ring is assumed to have a twisted envelope conformation. Due to the asymmetry of the molecule, 2 exists as an enantiomeric mixture.Transformations between (+)-and (-)-form by concomitant inversion at Ph and P7 d o not take place at room temperature.That 2 is a 2,3,4,6,7-penta-tert-butylbicyclo[3.2.0]heptaphosphane['*I can be explained by a destabilization of the structure type 1 as a result of increasing steric interactions with increasing bulkiness of the substituents at P6 and P7. Differing skeletal structures for R = M e , Et, iPr, and R=tBu have already been found in the P8& class of compounds.""] In the case 6 1 2, for the first time a molecular polycyclic phosphane is forced to form an annelated fourmembered ring as structural unit for steric reasons.""' A framework consisting of two annelated P4 rings, on the other hand, is so unfavorable energetically that the compound P{,tBu4 related to 2 is not a bicyclo[2.2.0]-but a bicyclo[3.1 .0]he~aphosphane.'~' ExperimentalA solution of rBuPCI2 (50.9 g, 0.32 mol) and PCI, (22.0g, 0.16 mol) in T H F (200 m L ) is added dropwise within 2 h to 500 mL of vigorously stirred boiling THF containing magnesium turnings (14.0 g, 0.58 mol; previously etched by evapomting a few grains of iodine). The yellow mixture is refluxed for a further I h, and, thereafter, allowed to cool to room temperature before complete removal of the solvent under reduced pressure. The residue is then taken up in 800 m L of n-pentane and the undissolved material filtered off, washed with pentane (3 x 400 mL) and the solvent removed from the combined filtrates. The yellow, viscous residue is dissolved in I00 mL of pentane, and P,tBu,, allowed to separate out by crystallization at room temperature ( I d). After filtration, the filtrate is evaporated down to 40 mL and then chromatographed twice on A1,03 using pentane with "P-NMR spectroscopic control. Final purification is achieved by preparative HPLC (Nucleosil-5-C18 column, methanol, receiver: -78°C). The solvent is rapidly condensed off (bath: -30°C. cooling trap: -196°C. pressure: 0.3 tom), leaving 0.59 g of pure 2 (2O;8 referred to tBuPCI,; not optimized).

The addition of Re(CO) 5 + [as Re(CO) 5 FBF 3 ] to P(CN) 3 and to P(CN) 2 affords the complexes [Re(CO) 5 ] 3 P(CN) 3 (BF 4 ) 3 and Re(CO) 5 P(CN) 2 , respectively. The spectroscopic data indicate that