Neue Kupferkomplexe mit Phosphaalkenliganden. Molekülstruktur von [Cu{P(Mes)C(NMe 2 ) 2 } 2 ]BF 4 (Mes = 2,4,6‐ t Bu 3 C 6 H 2 )

New Copper Complexes Containing Phosphaalkene Ligands. Molecular Structure of [Cu{P(Mes*)C(NMe 2 ) 2 } 2 ]BF 4 (Mes* = 2,4,6‐ t Bu 3 C 6 H 2 ) Reaction of equimolar amounts of the inversely polarized phosphaalkene t BuP=C(NMe 2 ) 2 ( 1a ) and copper(I) bromide or copper(I) iodide, respectively, affords complexes [Cu 3 X 3 {μ‐P( t Bu)C(NMe 2 ) 2 } 3 ] ( 2 ) (X =Br) and ( 3 ) (X = I) as the formal result of the cyclotrimerization of a 1:1‐adduct. Treatment of 1a with [Cu(L)Cl] (L = P i Pr 3 ; Sb i Pr 3 ) leads to the formation of compounds [CuCl(L){P( t Bu)C(NMe 2 ) 2 }] ( 4a ) (L = P i Pr 3 ) and ( 4b ) (L = Sb i Pr 3 ), respectively. Reaction of [(MeCN) 4 Cu]BF 4 with two equivalents of PhP=C(NMe 2 ) 2 ( 1b ) yields complex [Cu{P(Ph)C(NMe 2 ) 2 } 2 ]BF 4 ( 5b ). Similarly, compounds [Cu{P(Aryl)C(NMe 2 ) 2 } 2 ]BF 4 ( 5c (Aryl = Mes and 5d (Aryl = Mes*)) are obtained from ArylP=C(NMe 2 ) 2 ( 1c : Aryl = Mes; 1d : Mes*) and [(MeCN) 4 Cu]BF 4 in the presence of Sb i Pr 3 . Complexes 2 , 3 , 4a , 4b , and 5b‐5d are characterized by means of elemental analyses and spectroscopy ( 1 H‐, 13 C{ 1 H}‐, 31 P{ 1 H}‐NMR). The molecular structure of 5d is determined by X‐ray diffraction analysis.