New mono- and polynuclear alkynyl complexes containing phenylacetylide as terminal or bridging ligand. X-ray structures of the compounds NBu4[Pt(CH2C6H4P(o-tolyl)(2)-kappa C,P)(C CPh)(2)], [Pt(CH2C6H4P(o-tolyl)(2)-kappa C,P)(C CPh)(CO)], [{Pt(CH2C6

摘要

This work describes the synthesis of the compounds Q[Pt(CandP)(CCPh)(2)] (Q = Li+ (1), NBu4+ (2). CandP = CH2C6H4P(o-tolyl)(2)-kappa C,P) and their use as precursors for the preparation of homo- and heteropolynuclear complexes by reactions with Lewis acid species of transition metals, M (M = Cu(I), Ag(I), T1(I), Pd(II), Pt(II)). These reactions give rise to heteropolynuclear complexes that exhibit different bonding patterns for the bridging alkynyl ligands, depending on M. The reaction of 2 with readily available M+ (M = Cu, Ag) species affords the discrete tetranuclear clusters [{Pt(CandP)(CCPh)(2)M}(2)] (M = Cu (3), Ag (4)). The X-ray structure of 3 shows that in this complex both "Pt(CandP)(CCPh)(2)" fragments are connected by two d(10) metal centers and are stabilized by alkynyl bridging ligands, showing the stronger preference of the M-I centers (M-I = Cu, Ag) for the electron-rich alkynyl units than for the basic Pt(II) center. However, the reaction of 2 with T1PF(6) rendered the tentatively tetranuclear complex [{Pt(CandP)(CCPh)(2)T1}(2)] (5), containing Pt -> T1 dative bonds, which shows the higher affinity of thallium for the electron density of platinum(II) than for the alkynyl units. Moreover, the reaction of (NBu4)[Pt(CandP)(CCPh)(2)] (2) with the neutral complex [Pd(C6F5)(2)(THF)(2)] yields the compound (NBu4)[Pt(CandP)(CCPh)(2)Pd(C6F5)(2)] (11), in which the two alkynyl ligands are eta(2)-bonded to Pd(II) in such a way that the "cis-Pt(CCPh)(2)" fragment acts as a chelate ligand toward Pd(II). Meanwhile the reactions with the cationic and neutral Pt(II) complexes [Pt(CandP)(THF)(2)](+) and [Pt(C6F5)(2)(THF)(2)] produce the complexes [{Pt(CandP)(mu-CCPh)}(2)] (6) and (NBu4)[Pt(CandP)(mu-CCPh)(2)Pt(C6F5)(2)] (12), both containing the double mu(2)-eta(2)(sigma,pi)-alkynyl bridging system "Pt-2(mu-CCPh)(2)" as a consequence of an alkynylating process. This bridging system "Pt-2(mu-CCPh)(2)" can be broken by neutral ligands, L, to give mono(sigma-alkynyl) complexes of Pt(II). Thus, the complexes [Pt(CandP)(CCPh)L] (L = CO 7), py (8), tht (9), PPh3 (10)) have been obtained by reaction of 6 with L in a 1:2 molar ratio. When L = PPh3, the substitution reaction takes place with stereoretention, but not when L = CO, py, tht, as was conclusively established by an X-ray study on the complex [Pt(CH2C6H4P(o-tolyl)(2))(CCPh)(CO)] (7). The cis or trans disposition of the two sigma-C-donor ligands (C(CandP), sigma-CCPh) around the Pt center in complexes 6-10 and 12 seems to depend as much on the transphobia of pairs of trans ligands (T) as on the steric requirements of those in the cis configuration.