Synthesis, coordination chemistry and reactivity of cyano-functionalised N-pyrrolyl phosphines

摘要

The cyano-functionalised N-pyrrolyl phosphines PPh2(NC4H3CN-2) (L-1) and P(NC4H4)(2)(NC4H3CN-2) (L-2) have been prepared from the reaction of PClR2 (R = Ph, NC4H4) with lithium 2-cyanopyrrolide, itself generated in situ from 2-cyanopyrrole and BuLi. The reaction of L-1 or L-2 with [MCl2(cod)] gives [MCl2(L-kappa(1)P)(2)] (1, M = Pt, L = L-1; 2, M = Pd, L = L-1; 3, M = Pt, L = L-2; 4, M = Pd, L = L-2) and both cis-1 and trans-4 have been structurally characterised. The crystal structure of cis-1 reveals the presence of an unusually wide P-Pt-P angle [107.22(5)degrees], which has its origin in an intramolecular interaction between the two 2-cyanopyrrole rings. The reaction of L-1 with [M(dmba)(mu-Cl)](2) (Hdmba = N,N-dimethylbenzylamine) results in formation of [MCl(dmba)(L-1-kappa(1)P)] (5, M = Pt; 6, M = Pd). Compounds 5 and 6 react with TlPF6 to give oligomeric P,N-coordinated compounds of empirical formula [M(dmba)(L-1)][PF6]. The dimeric compound [Pt(dmba)(mu-L-1-kappa(1)P,kappa(1)N)](2)(PF6)(2) (7), has been isolated and structurally characterised, and coordination of the cyano groups leads to formation of a 12-membered ring. Compound 6 reacts with PhCH2CH(NH2)CH2OH in the presence of TlPF6 to yield [Pd(dmba)(PPh2NC4H3{C=NCH(CH2Ph)CH2O-2})]PF6 (8) in which the cyano group has been transformed into an oxazoline group. The molybdenum complex [MoCl(CO)(3)(eta(5)-C5H5)] reacts with L-1 to give [MoCl(CO)(2)(L-1-kappa(1)P)(eta(5)-C5H5)] (9) which has been structurally characterised. In contrast to the reaction of 5 or 6, compound 9 does not react with TlPF6 or AgBF4 to give tractable oligomeric products. Reaction of the rhodium complex [Rh(acac)(CO)(2)] with L-1 occurs to give [Rh(acac)(CO)(L-1-kappa(1)P)] (10). The infrared spectrum of 10 indicates the electronic properties of L-1 are very similar to those for PPh2(NC4H4). (C) 2003 Elsevier Science B.V. All rights reserved. [References: 42]