No abstract

No abstract

Reactions of dinuclear μ-chlorido rhodium(I) complexes [(RhL 2 ) 2 (μ-Cl) 2 ] (L 2 =cycloocta-1,5-diene, cod, 3; L 2 =P ∧ P: Ph 2 PCH 2 PPh 2 , dppm, 4a; Ph 2 P(CH 2 ) 2 PPh 2 , dppe, 4b; Ph 2 P(CH 2 ) 3 PPh 2 , dppp, 4c; Me 2 P(CH 2 ) 2 PMe 2 , dmpe, 4d) with γ-phosphino-functionalized propyl phenyl sulfides PhSCH 2 CH 2 -CH 2 PR 2 (R=Ph, 1; Cy, 2) afforded mononuclear rhodium(I) complexes of the type [RhCl(R 2 PCH 2 -CH 2 CH 2 SPh-κP)L 2 ] ] (R=Ph/L 2 =P ∧ P, 5a-c; R=Ph/L 2 =cod, 6; R=Cy/L 2 =P ∧ P, 7a-d; R = Cy/L 2 = cod, 8). Single-crystal X-ray diffraction analysis of 7b 3 C 6 H 6 exhibited the expected square-planar coordination of the rhodium atom having coordinated dppe-κ 2 P,P 0 , Cy 2 PCH 2 CH 2 CH 2 SPh-κP, and a chlorido ligand. Deprotonation of complexes 5b/c, 6, 7b/c, and 8 with lithium diisopropyl amide (LDA) yielded, with a selective deprotonation of the CH 2 group next to the sulfur atom (R-CH 2 group), complexes of the type [Rh{CH(SPh)CH 2 CH 2 PR 2 -κC,κP}L 2 ] (13b/c, 14, 15b/c, 16), thus being organorhodium intramolecular coordination compounds. Unexpectedly, reactions of the dppm complexes 5a and 7a with LDA led to deprotonation of the CH 2 group of the dppm ligand, resulting in formation of mononuclear rhodium complexes with a bis(diphenylphosphino)methanide-κ 2 P,P 0 ligand and a R 2 P ∧ SPh-κP,κS ligand, as well (17, 18). Single-crystal X-ray diffraction analysis of [Rh(dppm -H -κ 2 P,P 0 ) (Cy 2 PCH 2 CH 2 CH 2 SPh-κP,κS)] 3 THF (18 3 THF) shows the rhodium atom located in the center of a distorted square-planar environment having bound the P ∧ S-κP,κS ligand and the anionic dppm -H -κ 2 P, P 0 ligand with a very small P2-Rh-P3 angle (68.8(2)°) reflecting the small bite of that ligand. Addition of Tl[PF 6 ] to complexes 5-8 afforded cationic rhodium(I) complexes of the type [Rh(R 2 PCH 2 CH 2 CH 2 -SPh-κP,κS)L 2 ][PF 6 ] (9-12) bearing bidentately coordinated neutral co-ligands (P ∧ P: 9, 11; cod, 10, 12) and κP,κS-coordinated γ-phosphino-functionalized propyl phenyl sulfide ligands, as well. Single-crystal X-ray diffraction analysis of 10 reveals that the rhodium atom adopts a slightly distorted square-planar conformation. Complexes 9a-c and 11a-d were found to react with carbon monoxide, yielding cationic rhodium carbonyl complexes [Rh(CO)(R 2 PCH 2 CH 2 CH 2 SPh-κP,κS)(P ∧ P-κ 2 P,P 0 )] þ (19, 20), being in a dynamic equilibrium between two diastereomers each at room temperature, which was additionally verified by DFT calculations.

The dinuclear platina-β-diketone [Pt 2 {(COMe) 2 H} 2 (μ-Cl) 2 ] (1) reacted with 2-pyridyl-functionalized monoximes and with dioximes in the presence of NaOMe to yield oxime−diacetyl platinum(II) complexes [Pt(COMe) 2 (2-pyCRNOH)] (R = H, 4a; Me, 4b; Ph, 4c) and [Pt(COMe) 2 (HONCR−CRNOH)] (R/R = Me/Me, 5a; Ph/Ph, 5b; (CH 2 ) 4 , 5c; NH 2 /NH 2 , 5d), respectively. The strong intramolecular O−H•••O hydrogen bonds in these complexes give rise to an activation of the acetyl ligands for Schiff-base type reactions, thus forming with primary amines iminoacetyl platinum complexes [Pt(COMe)(CMeNHR′)(2-pyCRNO)] (R/R′ = H/ Bn, 6a; Me/Bn, 6b; Ph/Bn, 6c; H/CH 2 CH 2 Ph, 6d; H/CH 2 CHCH 2 , 6e; Bn = benzyl) and [{Pt(CMeNHR′) 2 (ONCR−CRNO)} 2 ] (R/R = Me/Me, 7a−d; Ph/Ph, 8a−d; (CH 2 ) 4 , 9a; R′ = Bn, a; CH 2 CH 2 Ph, b; CH 2 CHCH 2 , c; CH 2 CH 2 OH, d). The intramolecular N−H•••O hydrogen bonds in type 6−9 complexes make clear that protonated iminoacetyl ligands (i.e., aminocarbene ligands) and deprotoanted oxime ligands are present. These complexes could also be obtained in reactions of [Pt(COMe) 2 (NH 2 R′) 2 ] (3) with pyridyl-functionalized monoximes and with dioximes where type 4/5 complexes were found to be intermediates. In solution, the bis(iminoacetyl) complexes 7−9 were found to be present as dimers (as also 8a in the solid state) with smaller amounts of monomers. The importance of hydrogen bonds for activation of acetyl ligands was further evidenced by synthesis of complexes [Pt(COMe) 2 (2-pyCHNOMe)] ( 10) and [Pt(COMe) 2 (HONCMe−CMeNOMe)] (11) bearing O-methylated oxime ligands and their reactivty toward amines. The hydrogen-bond activated acetyl and iminoacetyl ligands in type 5, 7, and 8 complexes were found to undergo in CD 3 OD solutions facile H/D exchange reactions resulting in complexes bearing C(CD 3 )O/C(CD 3 )NDR′ ligands. The constitution of all complexes was unambiguously confirmed analytically, spectroscopically and in part by single-crystal X-ray diffraction analyses. Structural and NMR parameters as well as DFT calculations gave evidence for relatively strong intramolecular hydrogen bonds.

Reactions of the bis(benzylamine)platinum(II) complex [Pt(COMe) 2 (NH 2 Bn) 2 ] (2; Bn = benzyl) with (2py) 3 COR (2-py = 2-pyridyl), (2-py) 2 PhCOR, 5b)), respectively, having, due to a κ 2 coordination of the ligands, a 2-pyridyl (3), a phenyl (4), or a m-tolyl (5) ring as the pendant group. The identities of all complexes were unambiguously proved by highresolution mass spectrometric investigations and by NMR ( 1 H, 13 C, 195 Pt) and IR spectroscopy as well as by single-crystal X-ray diffraction analyses (3a−d). In methanol solution, complexes 3b−d and 5b show a dynamic behavior. The thermodynamic parameters of these dynamics have been determined by variable-temperature 1 H NMR measurements (Eyring plots). Furthermore, extensive DFT calculations will be presented, which indicate that the dynamics are caused by the interplay of hindered and respectively unhindered rotations of the substituent R and/or the pendant group.