Tetra-μ₃-iodo-tetrakis[(tri-tert-butylphosphine)copper(I)]

Abstract

The title compound, [Cu4I4(C12H27P)4], recovered from an attempt to prepare triisopropyl­silylthiol­ato(tri‐tert‐butyl­phosphine)copper(I), is found to be tetra­meric with a distorted heterocubane structure, one of the body diagonals of the cube being a crystallographic threefold rotation axis.

Tetra-μ3-iodido-tetrakis[(tri-n-butylphosphane-κP)copper(I)]

“…The crude product was dissolved in acetone/methanol (9:1) and cooled to -78°C, whereby the tetrameric complex precipitated. We were able to confirm the previously postulated tetrameric complex with a distorted heterocubane structure similar to the AsEt 3 derivative (Wells, 1936 Further comparison of the structure with other tetrameric copper complexes (Medina et al, 2005) reveals very similar Cu-P bond lengths despite the different σ-donor/π-acceptor strengths of Et 3 P, n-Bu 3 P, Ph 3 P and t-Bu 3 P, respectively.…”

“…In contrast, sterically less demanding phosphane ligands preferred the formation of tetrameric complexes. In this case, two different structures are possible, a pseudo-cubane structure 1 with triply-bridging halides [Cu(µ 3 -X)PR 3 ] 4 which was observed for PMe 3 (X = I) (Bowmaker et al, 1999), PEt 3 (X = Cl, Br, I) (Churchill & Kalra, 1974;Churchill, DeBoer, Donovan, 1975;Churchill, DeBoer, Mendak, 1975), t-Bu 3 P (X = Br, I) (Goel & Beauchamp, 1983;Medina et al, 2005), PMePh 2 (X = I) (Churchill & Rotella, 1977), and PPh 3 (X = Br, Cl, I) or an open-step tetramer 2 which was observed for PPh 3 (X = Br, I) (Churchill & Kalra, 1973;Churchill & Kalra, 1974;Churchill, DeBoer, Donovan, 1975;Churchill, DeBoer, Mendak, 1975; (Fig. 1).…”

“…The CuÁ Á ÁCu distance is markably short as compared with the reported distances of other tetranuclear copper phosphane complexes (Medina et al, 2005). Nevertheless there are examples for tetrameric copper complexes with a CuÁ Á ÁCu distance shorter than 2.700 Å (Blake et al, 2001;Churchill et al, 1982;Kim et al, 2008;Schramm, 1978).…”

“…Furthermore, complex [n-Bu 3 PCuI] 4 has the largest I-Cu-I angle and the smallest Cu-I-Cu angle as compared to the other complexes (Churchill & Kalra, 1974;Medina et al, 2005). Due to this very strong distortion the structure could be better described as two interpenetrating copper and iodine tetrahedrons.…”

“…For general background to this work, see: Ainscough et al (2001); Alyea et al (1985); Baker et al (1994); Barron et al (1984); Bowmaker et al (1989Bowmaker et al ( , 1992Bowmaker et al ( , 1994Bowmaker et al ( 1999Bowmaker et al ( , 2002; Churchill & Kalra (1973, 1974; Churchill, DeBoer & Donovan (1975) ;Churchill, DeBoer & Mendak (1975); Churchill & Rotella (1977, 1979; ; ; Gill et al (1976); Goel & Beauchamp (1983); Hadjikakou et al (1993); Herberhold et al (2003); Hermann et al (2001); Jansen (1987); Krause (2002); Mann et al (1936); Medina et al (2005); Moers & Op Het Veld (1970); Ramaprabhu et al (1993Ramaprabhu et al ( , 1998; Schwerdtfeger et al (2004); Soloveichik et al (1992); Wells (1936); Whitesides et al (1971). The CuÁ Á ÁCu distance is markably short as compared with the reported distances of other tetranuclear copper phosphane complexes (Medina et al, 2005).…”