Formation of 1,3‐Diphosphacyclobutadiene Complexes from Phosphaalkynes and Their Coordination Behavior

Abstract

AbstractBy using [(Cp″′Co)2tol] (Cp″′ = η5‐C5H2tBu3, tol = toluene), a new synthesis of the 1,3‐diphosphete complexes [Cp″′Co(η4‐P2C2tBu2)] (1a) and [Cp″′Co(η4‐P2C2iPr2)] (1b) was found, and their reactions with the Lewis acids W(CO)4 and CuI halides were investigated. The reaction of 1b with W(CO)4(nbd) (nbd = norbornadiene) leads to the complex [(Cp″′Co)(μ,η4:1‐{PCiPr}2)]2W(CO)4 (2) with the two diphosphete complexes 1b coordinated trans to a central W(CO)4 moiety. The reactions of 1a with CuI halides result in different products depending on the stoichiometry. In a 1:1 ratio, the dimeric compounds 3a–c [(Cp″′Co)(μ,η4:1‐{PCtBu}2)Cu(μ‐X)]2 (3a: X = Cl; 3b: X = Br, 3c: X = I) were isolated, whereas an excess of CuX gave the two‐dimensional polymers [({Cp″′Co}{μ3,η4:1:1‐(PCtBu)2})2(Cu{μ3‐X})4]n (6a: X = Cl, 6b: X = Br, 6c: X = I). From the reaction of 1a and 1b with CuBr and CuI in a 1:2 or 2:3 ratio, the one‐dimensional polymers [({Cp″′Co}{μ3,η4:1:1‐(PCR)2})({Cp″′Co}{μ,η4:1‐(PCR)2})(Cu{μ3‐X})4]n (4a: X = Br, R = iPr, 4b: X = I, R = iPr, 4c: X = I, R = tBu) are formed. From the reaction of 1a with CuI, a second product, [({Cp″′Co}{μ3,η4:1:1‐(PCtBu)2})(Cu{μ3‐I})4(MeCN)2]n (5), was isolated by using CH3CN for crystallization. The products were comprehensively characterized by spectroscopic methods, X‐ray crystallography, and 31P magic angle spinning (MAS) NMR spectroscopy.