Synthesis of PtRe2 and Pt2Re2 heterometallic complexes from the reaction of dirhenium carbonyl compounds with zerovalent complexes of platinum

Abstract

The monoacetonitrile complex [Re₂(CO)₉(MeCN), obtained from the reaction of [Re₂(CO)₁₀] with freshly prepared iodosobenzene in acetonitrile solutions, reacts with the secondary phosphines PR₂H in refluxing hexane to give the complexes [Re₂(CO)₉(PR₂H₂)](5a, R = Ph; 5b, R = Pr). Complexes 5, when heated to >170 °C in decalin, lose CO and are converted cleanly to [Re₂(µ-PR₂)(µ-H)(CO)₈](6a, R = Ph; 6b, R = Pr) while they react with [Pt(C₂H₄)(PPh₃)₂] to give [PtRe₂(µ-PR₂)(µ-H)(CO)₈(PPh₃)](7a, R = Ph; 7b, R = Pr), complexes containing a triangular PtRe₂ array with Pt(µ-PR₂)Re, Pt(µ-H)Re and Re–Re edges. Similarly, reaction of complexes 5 with [Pt(C₂H₄)₂{P(C₆H₁₁)₃}] gives [PtRe₂(µ-PR₂)(µ-H)(CO)₉{P(C₆H₁₁)₃}]8 containing Pt(µ-CO)Re, Pt(µ-H)Re and Re(µ-PR₂)Re edges. The trimetallic complex 8 slowly disproportionates to give [Re₂(µ-PR₂)(µ-H)(CO)₈]6 and ⅓[Pt₃(CO)₃{P(C₆H₁₁)₃}₃]. The reaction of 6a(µ-PPh₂) with [Pt(C₂H₄)₂{P(C₆H₁₁)₃}] gives the complex [PtRe₂(µ-PPh₂)(µ-H)(CO)₈{P(C₆H₁₁)₃}]7c in which the µ-PPh₂ ligand has migrated from a ReRe edge in 6a to a PtRe edge in 7. Further reaction of 7c with a second equivalent of [Pt(C₂H₄)₂{P(C₆H₁₁)₃}] yields the tetrametallic complex [Pt₂Re₂(µ-PPh₂)(µ-H)(CO)₈{P(C₆H₁₁)₃}₂]10(µ-PPh₂, µ-H and 2µ-CO on PtRe edges). Reaction of [Re₂(CO)₁₀] with [Pt(C₂H₄)₂{P(C₆H₁₁)₃}] gives [PtRe₂(CO)₁₀{P(C₆H₁₁)₃}] and [Pt₂Re₂(CO)₁₀{P(C₆H₁₁)₃}₂]12(4µ-CO on PtRe edges). The molecular structures of 7b, 10 and 12 have been determined by single-crystal X-ray diffraction studies. Crystal data as follows: 7b, orthorhombic, space group, Pbca, a= 14.951(2), b= 18.330(2), c= 25.715(2)Å, Z= 8, R= 0.0521 (R′= 0.0597) for 3700 data with I 3σ(I); 10, monoclinic space group, P2₁/n, a= 15.215(9), b= 19.633(9), c= 19.446(8)Å, β= 92.90(4)°, Z= 4, R= 0.0950 (R′= 0.1006) for 6068 data with I³σ(I); and 12, triclinic (paramonoclinic) space group, P, a= 11.567(4), b= 15.308(6), c= 16.178(6)Å, α= 89.87(3), β= 108.13(3), γ= 90.28(3)°, Z= 2, R= 0.0659 (R′= 0.0716) for 7166 data with I 3σ(I).