Novel trialkylstibane iridium(I) and iridium(III) complexes including the x‐ray crystal structure of five‐Coordinate [IrCl(C₂H₄)₂(SbiPr₃)₂]

Abstract

The reaction of [IrCl(C8H14)2]2 (2) with SbiPr3 in the presence of H2 yields the dihydridoiridium(III) complex cis,mer‐[IrH2Cl(SbiPr3)3] (3) which on treatment with CO and with HCCR (R = Ph, CO2Me) affords the octahedral derivatives [IrH2Cl(CO)(SbiPr3)2] (4) and [IrHCl(CCR)(SbiPr3)3] (5, 6), respectively. The stibane ligand trans to hydride in 5 and 6 is rather labile and, therefore, 5 and 6 react with pyridine to give [IrHCl(CCR)(py)(SbiPr3)2] (7, 8). Five‐coordinate bis‐(stibane)iridium(I) complexes [IrCl(C2H4)2(SbR3)2] (10–12) were prepared from [IrCl(C2H4)2]2 (9) and four equiv. of SbR3 (R = iPr, Me, Ph). The X‐ray crystal structural analysis of 10 reveals a distorted trigonal‐bipyramidal geometry around the metal center with one stibane ligand and the two olefinic ligands in the equatorial plane. Compound 10 reacts with NaC5H5 to yield [C5H5Ir(C2H4)(SbiPr3)] (13) and with different alkynes by partial or complete displacement of the ethene ligands to give trans‐[IrCl(PhCCPh)(SbiPr3)2] (14), [IrHCl(CCTol)(C2H4)(SbiPr3)2] (15), and trans‐[IrCl‐{CC(SiMe3)R}(SbiPr3)2] (16, 17), respectively.

An investigation of ethylene rotational barriers for 5-coordinate d 8 metal bis-ethylene complexes

“…In keeping with the above stability predictions, the majority of trigonal bipyramidal L 3 M(C 2 H 4 ) 2 complexes exhibit L 3 M(alkene) eq (alkene) eq coordination with stereochemically rigid ethylene ligands that are oriented in the TBP trigonal plane [13][14][15]17,20]. A single exception for stereochemical ethylene rigidity that we are aware of in this class of complexes is the terdentate system [j 3 -N,N,N-(S,S)-i Pr-pybox]Ir(C 2 H 4 ) 2 + , which has a reported ethylene rotational barrier of only 10.6 kcal mol À1 [21].…”

“…Ligand-dependence studies have been reported for (acac 0 )Rh(C 2 H 4 ) 2 (range: 11.7-19.2 kcal mol À1 ) [9], (Tp)Re(L)(CO)(C 2 H 4 ) (range: 8-12.7 kcal mol À1 ) [10], trans-(alkene) 2 W(CO) 4 (range: 9.3-11.6 kcal mol À1 ) [11], and (R 3 P) Pt(C 2 H 4 ) 2 (range: 10.2-13.0 kcal mol À1 , Me x Ph 3Àx P (x = 0, 1, 2, 3)) [12]. A number of bis-ethylene systems that are rigid on the NMR timescale have also been reported, including the Ir(I) compounds (R 3 Sb) 2 IrCl(C 2 H 4 ) 2 [13], (Me 2 PhP) 3 Ir(C 2 H 4 ) 2 + [14], (Et 3 P) 2 IrCl(C 2 H 4 ) 2 [15], Cp⁄Ir(C 2 H 4 ) 2 [16], and the Os(0) complex (Me 3 P) 2 Os(CO)(C 2 H 4 ) 2 [17].…”

Preparation and properties of sterically demanding and chiral distibine ligands

“…1 H NMR (CDCl 3 ): d = 6.80-8.15 (m) aromatic CH. 13 [Mo(CO) 4 (5)]. [Mo(CO) 4 (nbd)] (0.050 g, 0.17 mmol) was dissolved in ethanol (30 mL) the ligand (0.072 g, 0.17 mmol) was added dropwise as a CH 2 Cl 2 solution and the reaction was left to stir for 4 h. The solvent was removed under reduced pressure and the crude solid was washed with hexane and filtered.…”

Synthesis and coordinating properties of the facultative Sb2O- and As2O-donor ligands O{(CH2)2ER2}2 (E=Sb or As; R=Ph or Me)

“…This is probably mainly a consequence of the weakness of the Sb-C bonds, the lack of readily available Sb-containing precursor compounds and the early (incorrect) perception that stibines behave the same way as phosphines towards transition metals, but are poorer ligands [1][2][3]. Recent work from Werner and co-workers [4][5][6] and ourselves [7][8][9][10] has provided clear demonstrations of important differences in the chemistry of stibines compared to phosphines -for example, Werner has identified the first cases of bridging neutral Group 15 ligands in rhodium carbene complexes of Sb i Pr 3 . Furthermore, entry into the corresponding P i Pr 3 bridged species requires initial preparation of the bridged stibine species and then substitution of SbR 3 by PR 3 , reflecting profoundly different electronic behaviours for the two.…”