A Doubly Reduced Dipalladium Dibenzylideneacetone Complex

Xanthene diiodide reacts with Pd-2(dba)(3) in the presence of TMEDA via a double insertion of Pd into the C-I bonds, yielding the complex [XanPd(2)(TMEDA)(2)I-2] (1). Treatment of 1 with potassium naphthalenide in the presence of dba and 18C6 led to [Pd-2(dba)(2){K(18C6)}(2)] (2), where two reduced dba ligands span two Pd atoms via olefinic functions. The complex, which can also be readily generated from Pd-2(dba)(3) through reduction, crystallizes as a dimer composed by the interaction of two neighboring [K(18C6)](+) units with each other, while the second pair of cations coordinate an additional THF molecule each. The electronic structure of 2 was elucidated by SQUID measurements and DFT calculations.