Co-ordination chemistry of sulphines. Part 4. Influence of the phosphine cone angle on both the oxidative addition of carbon–sulphur and carbon–chlorine side bonds in [Pt⁰(PR₃)₂(XYCSO)] complexes and the (E)–(Z) isomerization

Abstract

The co-ordination compounds [ Pto{P(C6H11),}2(C12H8CSO)] (5a) (C12H8CS0 = fluorene-9-ylidenesuIphine), {(R'S),CSO}] (5c) (R' = p-MeC6ti,), and [PtO(P(C,Hll),}2{(€)-(PhS)CICSO}] (€)-(5d') may be synthesized with retention of configuration from [PtO(~od)~], P(C6H11)3, and the corresponding sulphines (cod = cyclo-octa-1,5-diene). The complexes (5a) and (5c) remain unchanged in CDCI, solution, while (Z)-(5b) isomerizes to (€)-(5b) and vice versa, until a 4 : 1 (€) : (Z) equilibrium is reached. The complex (€)-(5d') undergoes in CDCI, a fast oxidative addition of the C-CI side bond, yielding the kinetically preferred cis-(€)-[PtIICI( PhSCSO){P(C,-Hl l )3}2] (€)-(6d'), which then isomerizes to the thermodynamically more stable trans-(€)-and -(2)-[Ptl*CI-( ~h ~~~~) ( ~( ~6 ~l l ) , } , ] (€)-and (Z)-(7d'). This shows that replacement of the PPh, ligands by the bulkier P(C6H11), ligands increases the barrier to intramolecular C-S oxidative addition. An overall mechanism for the intramolecular C-S oxidative-addition and reductive-coupling reactions on Pt(PR3), centres (R = C6H11 or Ph) and the (€)-(2) isomerization of co-ordinated sulphines and metal-substituted sulphines (oxidative-addition pro-[Pt0{~(C6H11)3}~{(~)-(MeS)R'CSO}1 (E)-(5b), [pt"(p(C6H11)3}2((z)-(MeS)R'CSO}1 (z)-(5b), [pt0{p(C6H11)3}2ducts) is put forward. SULPHINES, XYC=S=O, have a bent planar structure 2-7 and are heterocumulenes; 2-7 they are related to sulphin ylanilines (aryl-N=S=O) and diarylsulphurdi-imines (aryl-N=S=N-aryl), the chemistry of which is being studied in our l a b ~r a t o r y . ~~~ Recently, we studied the oxidative-addition reaction of the C-C1 and C-S side bonds of sulphines which were q2-CS co-ordinated to Pto( PPh,),.l~10-~~ We found that the complexes [Pto( PPh,),{ (E)-(MeS)R'CSO}] 7 (E)-(2b), [Pt0(PPh3),{(2)-(MeS)R'CSO}] (Z)-(2b), and [PtO-(PPh,),{(R'S),CSO}] (2c) (R' = P-MeC6H4) were converted into their corresponding oxidative-addition products cis-(E)and -(Z)-[ PtlI( MeS) (R'CSO) (PPh,) 2] (E)and (2)-(3b), and cis-( E )and -(2)-[PtII (R'S) (R'SCS0)-(PPh,),] (E)and (.Z)-(3c).l9l1-l3 The structures of these complexes are shown in Figure 1.We have already deduced that the oxidative additions of these C-S side bonds proceed via an intramolecular process involving formation of q3-SCS co-ordinated intermediates.l,l2 Furthermore, both the q2-CS-co-ordination compounds and their oxidative-addition products undergo in solution (E)-( 2) sulphine isomerization.

Ferrocenyl phosphane nickel carbonyls: Synthesis, solid state structure, and their use as catalysts in the oligomerization of ethylene

“…The Tolman cone angle allows to evaluate the catalytic activity of organometallics, as described elsewhere [52][53][54]. The cone angles were calculated to 167 (3 0 ), 169 (3 00 ), 180 (4 with P1), 162 (4 with P2), 166 (6b 0 with P1), 170 (6b 0 with P2), 166 (6b 00 ), 163 (7 with P1), and 153°(7 with P2) ( Table 3) using the program STERIC [55,56] implying larger cone angles than PPh 3 (145°) [47].…”