LINEAR OLIGOPHOSPHAALKANES .23. NOVEL COPPER(I) COMPLEXES WITH ELECTRON-DEFICIENT TRIPLY BRIDGING SECONDARY PHOSPHIDO GROUPS MU-3-PRR' (R = IPR, TBU, R' = CH2-PR2, R = R' = PH)

The copper complexes Cu4(R2P–CH2-PR)Cl3(py)2 (2a, R = iPr; 2b, R = tBu) have been prepared by reaction of the corresponding silylphosphines R2P–CH2–PRSiMe3 with CuCl in the presence of pyridine (py). The structure of the hemietherate of 2a has been determined by X-ray diffraction. The compound crystallizes in the monoclinic space group C2/c with a = 18.197 (4) Å, b = 14.630 (3) Å, c = 24.926 (7) Å, β = 107.88 (2)°, and Z = 8. Refinement converged at R(Fo) = 0.050 for the 2778 observed reflections. Two crystallographic independent (Cu–Cl)2 bridges link 2a into chains, the third chlorine bridging the other two Cu atoms in the formula unit. The phosphido atom P(1) is bonded to two C and three Cu atoms. The three electron-deficient coplanar P(1)–Cu bonds are roughly equidistant (2.223 (3)–2.251 (3) Å); furthermore, the PCu3 fragment contains two Cu–Cu contacts (average 2.538 (4) Å) which are sufficiently short to be considered bonding. Treatment of polymeric [Cu(PPh2)]n with CuCl and PMe3 yields Cu4(PPh2)3Cl(PMe3)4 (4). It crystallizes in the monoclinic space group P21/c with a = 13.583 (2) Å, b = 19.586 (4) Å, c = 20.830 (4) Å, β = 100.32 (1)°, and Z = 4. Refinement converged at R(Fo) = 0.042 for 6090 observed reflections. The core of 4 may be described as a six-membered Cu3(PPh2)3 ring to which a CuCl is bound via two Ph2P groups; thus 4 possesses one electron-precise PCu2 bridge and two electron-deficient PCu3 fragments. As in 2a, the PCu3 fragments possess short Cu–Cu contacts (average 2.51(2) Å). Reaction of [Cu(PPh2)]., with PMe3 affords a copper(I) phosphido complex of composition [Cu(PPh2)-(PMe3)]n (5) for which a structure with μ2-PPh2 and μ3-PPh2 ligands is proposed. © 1990, American Chemical Society. All rights reserved.