Preparation and Properties of 1,2-Bis[(2,4,6-tri-t-butylphenyl)phosphinidene]cyclobuta[l]phenanthrene

Abstract

Sterically protected 1,2-bis[(2,4,6-tri-t-butylphenyl)phosphinidene]cyclobuta[l]phenanthrene (4) and its group(6) and group(10) transition metal complexes were prepared. X-ray crystallographic analysis of 4 revealed a planar structure of the diphosphinidenecyclobuta[l]phenanthrene moiety.

P,N-Chelate Complexes of Pd(II) and Pt(II) Based on a Phosphaalkene Motif: A Catalyst for the Overman−Claisen Rearrangement

“…Importantly, the observation of 195 Pt satellites ( 1 J PtP = 4486 Hz) provides convincing evidence for coordination of the phosphorus center to the platinum center. The coupling constant is similar to other phosphaalkene complexes such as F ·PtCl 2 ( 1 J PtP ≈ 4500 Hz) , but is higher than the monodentate phosphaalkene in [MesPCPh 2 ] 2 PtCl 2 ( 1 J PtP = 3950 Hz). Moreover, the downfield 31 P NMR chemical shift is consistent with retention of PC multiple bond character in the ligand upon complexation.…”

“…For comparison, lower field chemical shifts were observed for pyridyl phosphaalkene complexes containing the bulkier P−Mes* moiety (i.e., G ·PdCl 2 : R = H, 247 ppm; R = SiMe 3 , 283 ppm) . In contrast, higher field shifts are observed for complexes F ·PdCl 2 (R = C 4 H 4 S, 149.4 ppm; R = Fc, 134.9 ppm). ,, Interestingly, the 13 C{ 1 H} NMR signal assigned to the PC carbon resonates at 174.8 ppm ( 1 J PC = 52 Hz) for the complex 2b , which is further upfield than that found for the free phosphaalkene 1 (δ = 191.3, 1 J PC = 40 Hz; i.e., Δδ = 16.5). Similar upfield shifts were observed for the PdCl 2 complexes of G ·PdCl 2 (R = SiMe 3 , Δδ = 4.6) 14 and the phosphaalkene signals for complex F ·PdCl 2 (R = −(CH 2 ) 5 - ; Δδ = 16.0 and 14.7) .…”

Synthesis and structures of platinum diphenylacetylene and dithiolate complexes bearing diphosphinidenecyclobutene ligands (DPCB-Y)

“…Synthetic procedures for DPCB-Y ligands were previously reported. 7,27 [Pt(cod) 2 ] and [Et 4 N] 2 [Zn(dmit) 2 ] were prepared according to the literature. 28,29 [PtCl 2 (DPCB-H)] and The data were observed in CHCl 3 at room temperature.…”

Synthesis and Structures of Platinum(0) Alkyne Complexes with Extended π-Conjugated Systems

“…We herein describe that platinum(0) alkyne complexes with extended π-conjugated systems are successfully prepared using 1,2-bis[(2,4,6-tri- tert -butylphenyl)phosphinidene]cyclobuta[ l ]phenanthrene (DPCB-phen) as an auxiliary ligand (eq ), which is a 1,2-fused compound of 1,2-diphenyl-3,4-bis[(2,4,6-tri- tert -butylphenyl)phosphinidene]cyclobutene (DPCB) . As has been already demonstrated for group 9 and 10 metal complexes, DPCB as a low-coordinated phosphorus compound possesses extremely low-lying π* orbitals and acts as a strong π-acceptor toward transition metals. , It has been found that this unique electronic property effectively induces π-conjugation over the molecules.…”