Pentamethylcyclopentadienyl-rhodium and -iridium complexes. Part 29. Syntheses and X-ray structure determinations of [{Rh(C5Me5)}2(OH)3]OH·11H2O and [{lr(C5Me5)}2(OH)3]O2CMe·14H2O and related complexes

Abstract

The complexes [{M(C₅H₅)}₂(OH)₃]X·nH₂O (M = Rh, X = PF₆ and OH; M = Ir, X = O₂CMe, OH, and BPh₄) have been prepared. Single-crystal X-ray structure determinations have been carried out on [{Rh(C₅Me₅)}₂(OH)₃]OH·11H₂O (2c) and on [{Ir(C₅Me₅)}₂(OH)₃]O₂CMe·14H₂O (3a). Both show two metal atoms each η⁵-bonded to a C₅Me₅ ligand and bridged by three hydroxo-ligands with Rh ⋯ Rh 2.973 8(8)Å, Ir ⋯ Ir 3.070 9(7)Å, Rh–O (mean) 2.109 Å, Ir–O (mean) 2.120 Å, Rh–O–Rh (mean) 89.6(1)°, and Ir–O–Ir (mean) 92.8(3)°. Both (2c) and [{lr(C₅Me₅)}₂(OH)₃]OH·nH₂O are very strong bases in water. Reaction of [{Rh(C₅Me₅)}₂Cl₄](1) with Ag₂SO₄ gave Rh(C₅Me₅)(SO₄)·2H₂O which probably exists in water as the dication [Rh(C₅Me₅)(H₂O)₃]²⁺ and which is quantitatively carbonylated (20 °C, 1 atm, 48 h) to [Rh(C₅Me₅)(CO)₂]. The carbonato-complex Rh(C₅Me₅)(CO₃)·2H₂O was obtained from (1) and Ag₂CO₃ or by air-oxidation of [{Rh(C₅Me₅)}₂(CO)₂]. Reaction of [{Rh(C₅Me₅)}₂(OH)₃]Cl with P(OMe)₃ gave the unexpected methylrhodium complex [Rh(C₅Me₅)Me{P(OMe)₃}₂]⁺ as well as [Rh(C₅Me₅){P(OMe)₃}₃]²⁺.