INCORPORATION OF A COMPLEXED ALH FRAGMENT INTO A METALLACYCLE - PREPARATION AND CHARACTERIZATION OF CPCOC4PH4ALH.NET3

The reaction of Cp(PPh3) activated CoCPhCPhCPhCPh with AlH3.NEt3 proceeds smoothly at elevated temperatures to produce CpCoC4Ph4AlH.NEt3 (6) in 80% isolated yield. The composition and proposed structure is based on H-1, C-13, and Al-27 NMR, IR, and other data. The green compound is extremely water sensitive and modestly sensitive to oxygen. Hydrolysis leads to quantitative formation of CpCo(eta-4-C4Ph4H2) (7). Addition of Et2OBF3 leads to a 60% isolated yield of CpCo(eta-5-C4Ph4BF) (5), which has been fully characterized spectroscopically. The CpCo(eta-5-C4Ph4BF) derivative reacts with H- to yield primarily CpCo(eta-5-C4Ph4BH) (3). Reaction with propylene results in the rapid destruction of CpCoC4Ph4AlH.NEt3 with the concomitant loss of almost-equal-to 10 propylene molecules. However, the intractable products could not be characterized.