Substituted Metal Carbonyls. 27.¹ Synthesis, Structures, and Metal−Metal Bonding of a Ferrocenylphosphine exo-Bridged Cluster with Two Heterometallic Triangles, [AuMn₂(CO)₈(μ-PPh₂)]₂(μ-dppf), and a Twisted-Bowtie Cluster, PPN⁺[Au{Mn₂(CO)₈(μ-PPh₂)}₂]^- (dppf = 1,1‘-Bis(diphenylphosphino)ferrocene)

Abstract

Redox condensation of PPN[Mn2(CO)8(μ-PPh2)] (1; (PPN = N(PPh3)2) with Au2Cl2(μ-P−P) (P−P = (C5H4PPh2)2Fe (dppf), Ph2PC2H4PPh2 (dppe)) gives two hexanuclear Au−Mn clusters [AuMn2(CO)8(μ-PPh2)]2(μ-P−P) (P−P = dppf, (2), dppe (4)), both of which contain a diphosphine bridging two Mn2Au triangles. Complex 2 is formed via an intermediate, AuCl(μ-dppf)[AuMn2(CO)8(μ-PPh2)], (3), which was isolated. Bridge cleavage of 2 occurs at thf reflux with PPh3 and room temperature with P(OEt)3 to give the triangular clusters [(PR3)AuMn2(CO)8(μ-PPh2)] (R = Ph (5), OEt (6)), respectively. The latter exchange of dppf with P(OEt)3 is reversible in solution. Condensation of 1 with AuCl(SMe2) gives an anionic pentanuclear cluster, PPN[Au{Mn2(CO)8(μ-PPh2)}2] (7). Complexes 2 and 7 were structurally characterized by single-crystal X-ray diffractometry. Complex 2, which is centrosymmetric with Fe in dppf at a crystallographic inversion center, consists of a ferrocenylphosphine bridging two heterometallic triangles (Au−Mn = 2.660(1) and 2.776(1) Å; Mn−Mn = 3.049(2) Å). Complex 7 is made up of two planar AuMn2P metallacycles fused at Au at an angle of 85.50(4)°. With crystallographic C 2 symmetry, a twisted-bowtie skeleton resulted with gold at its center. Both Au−Mn (mean 2.806(1) Å) and (PPh2-bridged) Mn−Mn (3.105(2) Å) lengths are significantly longer than those in 2. The Mn−Mn bond of 2 is also significantly longer than that of 1. Fenske−Hall MO calculations on 1, 2, and 7 together with Mn2(CO)8(μ-H)(μ-PPh2) (8) and (PPhMe2)AuMn2(CO)8(PPh2) (9) indicate that aside from 1, all the complexes, including 2 and 7, give a negative overlap population in the Mn−Mn interactions. The Mn−Mn distance appears to be determined by the strength of the AuMn2 interaction and/or the size of H compared to Au. The weaker Mn−Mn and Au−Mn interactions in 7 (as compared to those in 2 and 9, respectively) are likely to be caused by the absence of Au orbital reinforcement in the direction of the Mn2 moiety as a consequence of symmetry.

Synthesis, solid state structure and spectro-electrochemistry of ferrocene-ethynyl phosphine and phosphine oxide transition metal complexes

“…13 3.81 (pt, J HH = 1.7 Hz, 4H, H b C 5 H 4 /FcC"CPt), 3.84 (s, 10H, C 5 H 5 / FcC"CPt), 3.86 (pt, J HH = 1.7 Hz, 4H, H a C 5 H 4 /FcC"CPt), 4.19 (s, 10H, C 5 H 5 /FcC"CP), 4.23 (pt, J HH = 1.9 Hz, 4H, H b /C 5 H 4 /FcC"CP), 4.55 (pt, J HH = 1.9 Hz, 4H, H a /C 5 H 4 /FcC"CP), 5.29 (s,CH 2 Cl 2 ), 7.44-7.50 (m, 12H, C 6 H 5 ), 8.08-8.19 (m, 8H, C 6 H 5 …”

Diphosphine as an Overhead Bridge across a Heterometallic M−M‘ Bond. A Flexible Cluster System in (P−P)AuMn2(CO)7(μ-PPh2) that Accommodates All Common Diphosphines

“…Complexes 1a (P−P = Fe(C 5 H 4 PPh 2 ) 2 (dppf)) and 1d (P−P = Ph 2 P(CH 2 ) 2 PPh 2 (dppe)), which were a subject of our earlier report, are examples of complexes with two heterometallic triangles linked exclusively by a diphosphine bridge, giving a hexametallic framework. The other derivatives, 1b (P−P = Ph 2 P(CH 2 ) 4 PPh 2 (dppb)), 1c (P−P = Ph 2 P(CH 2 ) 3 PPh 2 (dppp)), and 1e (P−P = Ph 2 PCH 2 PPh 2 (dppm)), can also be prepared accordingly.…”

“…The rupture of these bonds destroys the underlying principle in using heterometallics as substrates. In this note, using [AuMn 2 (CO) 8 (μ-PPh 2 )] 2 (μ-P−P) (P−P = diphosphine), 1 , as a model, we report a simple yet effective strategy to preserve the M−M‘ entity, by protecting it with an overhead bridge. We opt for a diphosphine because of its convenience and its ability to bind to a range of metals.…”

Porous graphitic carbon (PGC) high-performance liquid chromatography of diphosphine-bridged complexes with heteronuclear Au-M (M=Mn, Re) bonds

“…The separation of complexes 7 and 8 is shown in Figure 5; the mobile phase was hexane:tetrahydrofuran (92:8). For this pair of complexes, besides molecular size, the difference in metal-metal bond polarity (with Re5 +-Au6-being more polar than Mn6+-Au6-due to the larger size and lower electronegativity of Re compared to Mn [8,15]) resulted in the elution of complex 7 before that of 8. Several workers have attempted to correlate the chromatographic behaviour of PGC as a stationary phase in HPLC [10,11,18].…”

“…HPLC runs were carried out at least in triplicate, and the reproducibility of retention times between runs was _+ 3 % or better. [15], (OC)5MnAuPPh3 [16] and (OC)sReAuPPh3 [16] were prepared according to literature methods.…”