Copper-tungsten complexes with bridging tolylmethylidyne ligands: Crystal structure of the compound [CuW2(μ3-CC6H4Me-4)(CO)4(PPh3)(η-C5H5)2]·CH2Cl2

Abstract The complexes [W(CC 6 H 4 Me-4)(CO) 2 (η-C 5 H 5 )] and [Cu(NCMe) 4 ][PF 6 ] in dichloromethane combine to form the salt [Cu&W(CC 6 H 4 Me-4)(CO) 2 (η-C 5 H 5 )& 2 ][PF 6 ], but the latter very readily dissociates in solution releasing the tolylmethylidynetungsten compound. The more stable salt [CuW(μ-CC 6 H 4 Me-4)(CO) 2 (NCMe)(PPh 3 ) (η-C 5 H 5 )][PF 6 ] is obtained by addition of [W(CC 6 H 4 Me-4)(CO) 2 (η-C 5 H 5 )] to a dichloromethane solution of [Cu(NCMe) 4 ][PF 6 ] previously treated with 1 mol equivalent of PPh 3 . In the presence of additional PPh 3 , however, no copper-tungsten complex is formed. Several reactions of [CuW(μ-CC 6 H 4 Me-4)(CO) 2 (NCMe)(PPh 3 )(η-C 5 H 5 )][PF 6 ] have been studied, but these led only to release of [W(CC 6 H 4 Me-4)(CO) 2 (η-C 5 H 5 )]. The compounds [&CuH(PPh 3 )& 6 ] and [W(CC 6 H 4 Me-4)(CO) 2 (η-C 5 H 5 )] react in toluene at room temperature to give [W(CO) 2 (η 3 -CH 2 C 6 H 4 Me-4)(η-C 5 H 5 )] and the new cluster compound [CuW 2 (μ 3 -CC 6 H 4 Me-4)(CO) 4 (PPh 3 )(η-C 5 H 5 ) 2 ]. The structure of the latter species has been established by X-ray diffraction. A CuW 2 metal triangle [CuW 2.640(2) and 2.610(2), and WW 3.064(1) A] is asymmetrically capped by a CC 6 H 4 Me-4 group [μ 3 -CCu 2.130(9), μ 3 -CW 2.035(9) and 2.122(9) A]. The copper atom is ligated by a PPh 3 molecule, and each tungsten by an η 5 -cyclopentadienyl and two carbonyl groups. The copper atom is weakly coordinated in a semi-bridging manner by two of the CO ligands, one on each tungsten, and is also very weakly bound to a third. The molecule undergoes dynamic behaviour in solution.