A metal and a metalloid Lewis acid bridged by a μ2-phosphinidene

Dinuclear phosphinidene complexes bridging two transition metal centres are now well established. However, a phosphinidene bridging a metal centre and a main group Lewis acid has not yet been reported. Herein, we describe the generation of a highly reactive phosphinidene complex bridging a tungsten and a boron centre. Furthermore, the synthesis and dyotropic rearrangement of a P-borane adduct of an N-methylimidazole-stabilized neutral, electrophilic terminal phosphinidene complex is reported.

Gold(I) and related heterometallic derivatives of dimolybdenum complexes with asymmetric phosphinidene bridges

The phosphinidene-bridged complexes [Mo2Cp2(μ-κ(1):κ(1),η(6)-PR*)(CO)2] (1), [Mo2Cp2(μ-κ(1):κ(1),η(4)-PR*)(CO)3] (2), [Mo2Cp(μ-κ(1):κ(1),η(5)-PC5H4)(η(6)-HR*)(CO)2] (3), and [Mo2Cp2(μ-κ(1):κ(1)-PH)(η(6)-HR*)(CO)2] (4) were examined as precursors of heterometallic gold(I) and related derivatives (Cp = η(5)-C5H5, R* = 2,4,6-C6H2(t)Bu3). These complexes reacted with [AuCl(THT)] to give the corresponding derivatives [AuMo2ClCp2(μ-κ(1):κ(1):κ(1),η(6)-PR*)(CO)2], [AuMo2ClCp2(μ-κ(1):κ(1):κ(1),η(4)-PR*)(CO)3] (Au-Mo = 2.8493(6) Å), [AuMo2ClCp(μ-κ(1):κ(1):κ(1),η(5)-PC5H4)(CO)2(η(6)-HR*)], and [AuMo2ClCp2(μ3-PH)(CO)2(η(6)-HR*)] formally resulting from the addition of an acceptor AuCl moiety to the short Mo-P bond of the parent substrates almost perpendicular to the corresponding Mo2P plane. The chloride ligand was easily displaced upon reaction of the PC5H4-bridged gold complex with K[MoCp(CO)3] to give the tetranuclear derivative [AuMo3Cp2(μ-κ(1):κ(1):κ(1),η(5)-PC5H4)(CO)5(η(6)-HR*)] (Au-Mo = 2.711(2) and 2.807(2) Å). Compound 1 also reacted with HgI2 to give a hexanuclear complex [HgMo2Cp2(μ-I)I(μ-κ(1):κ(1),η(6)-PR*)(CO)2]2 containing dative Mo→Hg bonds (2.820(1) and 2.827(1) Å), whereas complex 3 gave the μ3-PR bridged complex [HgMo2CpI2(μ-κ(1):κ(1):κ(1),η(5)-PC5H4)(CO)2(η(6)-HR*)]. Complexes 1 to 4 also reacted easily with [AuL(THT)]PF6 (L = THT, P(p-tol)3, PMe3, P(i)Pr3) to give the corresponding cationic trinuclear derivatives [AuMo2Cp2(μ-κ(1):κ(1):κ(1),η(6)-PR*)(CO)2L](PF6) (Au-Mo = 2.8080(3) Å for L = P(p-tol)3), [AuMo2Cp2(μ-κ(1):κ(1):κ(1),η(4)-PR*)(CO)3L](PF6), and [AuMo2Cp(μ-κ(1):κ(1):κ(1),η(5)-PC5H4)(CO)2(η(6)-HR*){P(p-tol)3}](PF6). The blue, analogous PH-bridged complexes were more conveniently isolated as tetra-arylborate salts [AuMo2Cp2(μ3-PH)(CO)2(η(6)-HR*)L](BAr'4) (Au-Mo = 2.8038(6) Å for L = P(i)Pr3; Ar'= 3,5-C6H3(CF3)2]. Compounds 1, 3, and 4 reacted readily with the cation [Au(THT)2](+) (as PF6(-) or BAr'4(-) salts) in a 2:1 ratio to give respectively the corresponding pentanuclear derivatives [Au{Mo2Cp2(μ-κ(1):κ(1):κ(1),η(6)-PR*)(CO)2}2](PF6), [Au{Mo2Cp(μ-κ(1):κ(1):κ(1),η(5)-PC5H4)(CO)2(η(6)-HR*)}2](PF6) (Au-Mo = 2.7975(7) and 2.8006(7) Å), and [Au{Mo2Cp2(μ3-PH)(CO)2(η(6)-HR*)}2](BAr'4) (Au-Mo = 2.8233(8) and 2.8691(7) Å). Related silver complexes were obtained from the reaction of 3 and 4 with [AgCl(PPh3)]4 after spontaneous symmetrization, while reaction of 1 with [Cu(NCMe)4]PF6 in a 2:1 ratio yielded the analogous copper complex [Cu{Mo2Cp2(μ-κ(1):κ(1):κ(1),η(6)-PR*)(CO)2}2](PF6). All the above cationic gold complexes having (μ-κ(1):κ(1):κ(1),η(6)-PR*) ligands (but not the copper complex) rearranged into [Au{Mo2Cp(μ-κ(1):κ(1):κ(1),η(5)-PC5H4)(CO)2(η(6)-HR*)}2](PF6) in refluxing 1,2-dichloroethane solution.

The series Os4(µx-η2-C2Ph2)(CO)14–n (n = 0, 1, 2; x = n + 2) — Models for site-specific surface catalysts

The cluster Os4(µ-η2-C2Ph2)(CO)14 (1) has been prepared from the reaction of Os4(CO)14 and C2Ph2 in CH2Cl2 at 25 °C. Other minor products include the known clusters Os3(µ3-η2-C2Ph2)(CO)10 and Os3(µ-η4-C4Ph4)(CO)9. The structure of 1 reveals an approximately planar C2Os4 skeleton with a dimetallacyclobutene ring (C—C = 1.32(4) Å) and a flat butterfly Os4 unit (Os—Os range = 2.859(2)–2.916(2) Å). The 13C{1H} NMR spectrum of 1 indicates the carbonyl ligands are rigid at room temperature. Stirring 1 in CH2Cl2 for 2 days (ambient temperature) afforded Os4(µ3-η2-C2Ph2)(CO)13 (2). The Os atoms in 2 also have an almost flat butterfly arrangement (Os—Os range = 2.7392(7)–2.8947(6) Å) with the alkyne ligand located over one of the Os3 triangles. The 13C NMR data for 2 are consistent with rapid rotation on the NMR timescale of the hinge Os(CO)3 units at 21 °C, but slow rotation at –50 °C. Heating 2 at 40 °C gave Os4(µ4-η2-C2Ph2)(CO)12 (3) after 2 days. Cluster 3 has the common butterfly arrangement of Os atoms with the C2Ph2 bound to all four metal atoms (Os—Os range = 2.7457(5)–2.8742(5) Å). The 13C{1H} NMR spectra of 3 at 21 and 90 °C indicate there is rapid CO exchange of the carbonyls of the two types of Os(CO)3 units, but not between the units. The spectrum at –90 °C indicates one of the rotations (presumed to be that involving the carbonyls of the wingtip Os(CO)3 units) is slowed on the NMR timescale. Compounds 1–3 form a unique series of clusters that have an alkyne ligand bound to two, three, and four metal atoms. Compound 1 is a model for a corner, compound 2 for a planar surface, and compound 3 a step site, in site-specific surface catalysts.Key words: osmium cluster, diphenylacetylene, dimetallacyclobutene, carbonyl exchange, surface catalysis.

Reactivity of electrophilic µ-phosphinidene complexes with heterocumulenes: formation of the first σ-π-aminophosphaimine complexes [Mn2(CO)8{µ-η1,η2-P(NiPr2)NR}] and diazoalkane insertions into metal–phosphorus bonds

The bridging phosphinidene complexes [Mn2(CO)8(micro-PNiPr2)] and [Co2(CO)4(micro-dppm)(micro-PNR2)](NR2=NiPr2, TMP) react with heterocumulenes RN3, CH2N2 and Ph2C=N=N to form complexes with micro-eta1,eta2-aminophosphaimine, micro-eta1,eta2-aminophosphaalkene and micro-eta1,eta2-aminophosphadiphenylmethylazaimine ligands, respectively.