1:1 Adducts of Copper(I) and Silver(I) Halides with the Olefinic Phosphane Tri(1-cyclohepta-2,4,6-trienyl)phosphane. Molecular Structures of CuX[P(C 7H7)3] (X = Cl, Br), AgCl[P(C7H 7)3] and {Cu(μ3-I)[P(C7H 7)3]}4

Abstract

A suspension of CuX (X = Cl, Br) or AgCl in organic solvents (such as CH2Cl2) reacts with P(C7H7) 3 (1) in a molar ratio 1:1 to give the mononuclear adducts CuX[P(C7H7)3] (X = Cl (2a), Br (2b)) and AgCl[P(C7H7)3] (3a) which crystallize as isotypic compounds in the orthorhombic space group Pnma (Z = 4). In the crystal, two (of the three) cyclohepta-2,4,6-trienyl substituents are present in the boat conformation, thus establishing a loose long-distance interaction between the central double bond and the metal atom. A distorted pseudo-tetrahedral coordination sphere is assumed to exist around the metal atom, with large P-M-X angles of 165.49(8)° (2a), 162.07(7)° (2b) and 168.54(3)° (3a), respectively. The tetrameric 1:1 adduct {Cu(μ3-I)[P(C 7H7)3]}4(2c) which was obtained from CuI and 1 in boiling ethanol, has also been characterized by X-ray crystallography (monoclinic space group P2(1)/n, Z = 4); it contains all 12 cyclohepta-2,4,6-trienyl substituents in the chair conformation. The NMR spectra (1H, 13C, 31P) of the new complexes 2a-c and 3a indicate non-rigid structures in solution. At room temperature, the 31P NMR signal of 3a appears as a doublet with an averaged coupling constant, 1J(Ag,P), of 700.1 Hz, whereas at -45°C the two expected doublets are clearly discernible with coupling constants 1J(107Ag,31P) = 671.0Hz and 1J( 109Ag,31P) = 774.4 Hz, respectively.