Synthese und Struktur eines polyspirocyclischen Ylidkomplexes des Nickels mit vier chiralen Zentren

Synthesis and Structure of a Polyspirocyclic Ylide complex of Nickel with four Chiral Centres. The bicyclic phosphorus ylideλ⁵-phosphaspiro[5.5]undec-5-ene (1) is metalated with one equivalent of methyllithium to yield 2, which reacts with bis (trimethylphosphane)nickel dichloride in a molar ratio of 2:1 to form the polyspirocyclic nickel ylide complex 3. X-ray diffraction analysis of the mononuclear complex 3 shows a centrosymmetric structure with an approximate squareplanar coordination of nickel to four chiral carbon atoms; yet the total molecule is an achiral system.