Synthesis and Characterizations of Bismuth-Bridged Triiridium Carbonyl Complexes Containing Germyl/Germylene and Stannyl/Stannylene Ligands

Abstract

The reaction of Ir3(CO)9(μ3-Bi) with Ph3GeH yielded the compound Ir3(CO)6(GePh3)3(μ3-Bi)­(μ-H)3 (1). When 1 was heated to reflux in hexane, it was transformed into the compound Ir3(CO)6(μ-GePh2)3(μ3-Bi) (2), which contains three bridging GePh2 ligands by loss of 3 equiv of benzene. The reaction of Ir3(CO)9(μ3-Bi) with Ph3SnH yielded the compounds Ir3(CO)6(SnPh3)3(μ3-Bi)­(μ-H)3 (3) and Ir3(CO)6(μ-SnPh2)3(μ3-Bi) (4), respectively. Compounds 1–4 were characterized crystallographically. Compounds 1 and 3 each have three terminally coordinated EPh3 (E = Ge, Sn) ligands in equatorial coordination sites, one on each of the iridium atoms. In solution compounds 1 and 3 exist as two isomers. The major isomer has the structure found in the solid state. The two isomers interconvert rapidly on the NMR time scale by tripodal, trigonal-twist rearrangement mechanisms: for 1, ΔH ⧧ = 66.6 kJ/mol and ΔS ⧧ = 1.58 J/(K mol), and for 3, ΔH ⧧ = 65.6 kJ/mol and ΔS ⧧ = −1.4 J/(K mol). The molecular orbitals and UV–vis spectra of 2 were calculated and analyzed by ADF DFT computational treatments. The visible spectrum is dominated by transitions from the Ir–Bi bonding orbitals HOMO-3 and HOMO-4 to an Ir–Ir antibonding orbital, the LUMO, in the Ir3 core of the complex.

The Addition of Gold and Tin to Bismuth–Triiridium Carbonyl Complexes

“…In addition, compound 3 contains two SnPh 3 ligands that occupy equatorial coordination sites, one on each of the two Ir(CO) 2 groups. The Ir−Sn bond distances are similar in length, Ir3−Sn1 = 2.6415(18) Å, Ir2−Sn2 = 2.6413 (19) Å, and are similar to those found in the compounds Ir 3 (CO) 6 (SnPh 3 ) 3 -(μ-H) 3 (μ 3 -Bi) 5 and Ir 3 (CO) 6 (SnPh 3 ) 3 (μ-SnPh 2 ) 3 . 27 There is a hydride ligand bridging the Ir−Ir bond between the two tinsubstituted iridium atoms.…”

“…Similar dynamical activity was observed for the very similar compound Ir 3 (CO) 6 (GePh 3 ) 3 -(μ-H) 3 (μ 3 -Bi). 5 The Ir−Ir bond distances in 3 are similar to those found in 2, Ir1−Ir3 = 2.8211(14) Å and Ir1−Ir2 = 2.8221(13) Å, except for the hydride-bridged Ir−Ir bond, Ir2−Ir3 = 2.9098(14) Å, When compound 2 was allowed to react with HSnPh 3 in the presence of H 2 O for 24 h at 25°C, compound 3 was obtained in 24% yield, together with the new compound 4 in 13% yield. It was subsequently shown that compound 4 can be obtained in an even better yield (24%) directly by the reaction of 3 with H 2 O.…”

“…4 We have already shown that HSnPh 3 and HGePh 3 can be added to Ir 3 (CO) 9 (μ 3 -Bi) to yield products containing terminal EPh 3 ligands, Ir 3 (CO) 6 (EPh 3 ) 3 (μ 3 -Bi)(μ-H) 3 , E = Sn and Ge, and bridging EPh 2 ligands, Ir 3 (CO) 6 (μ-EPh 2 ) 3 -(μ 3 -Bi), E = Sn and Ge (eq 2). 5 We have recently shown the molecule PhAu(PPh 3 ) can be oxidatively added to substitutionally active metal carbonyl cluster complexes under mild conditions to yield transition metal−gold complexes containing phenyl ligand(s), e.g., eqs 3−5. 6−8 With this in mind, we have now embarked on a study to synthesize new iridium−bismuth complexes derived from Ir 3 (CO) 9 (μ 3 -Bi) that contain gold and gold plus tin ligands that could potentially be converted into new multimetallic nanoparticles for applications in selective oxidation catalysis.…”

Iridium–Bismuth Cluster Complexes Yield Bimetallic Nano-Catalysts for the Direct Oxidation of 3-Picoline to Niacin

“…20 We have recently prepared a number of iridium-bismuth complexes containing germanium and tin ligands from complex 1 by reactions with HGePh 3 and HSnPh 3 . 21 We have now found that 1 reacts with BiPh 3 to yield the new higher nuclearity complex Ir 5 (CO) 10 (μ 3 -Bi) 2 (μ 4 -Bi), 2 in high yield (91%), see Scheme 1. Compound 2 was characterized crystallographically by singlecrystal X-ray diffraction and an ORTEP diagram of its molecular structure is shown in Figure 2.…”

Iridium–bismuth carbonyl cluster complexes

“…( 1 ) There are very few examples of iridium-bismuth carbonyl cluster complexes [3][4][5]. We have previously shown that the compound Ir 3 (CO) 9 (µ 3 -Bi), 1 [3] can be converted into the higher nuclearity complex Ir 5 (CO) 10 (µ 3 -Bi) 2 (µ 4 -Bi) by reaction with BiPh 3 , eq.…”