Some Chemistry of the Heterobimetallic Complexes and PF6 (M = Rh or Ir, dppm = Ph2PCH2PPh2). Structure of CMe)Rh(CO)>

Article abstract of DOI:10.1039/DT9870002171

The previously described complex <(OC)3Mo(μ-dppm)2Rh(CO)CI> (1a) does not readily undergo metathesis, thus when treated with NaI it gave <(OC)3Mo(μ-dppm)2Rh(CO)I> in only ca. 50percent yield even after 3 h.However, the salt <(OC)3Mo(μ-dppm)2Rh(CO)2>PF6 (2a) when treated with NH4Br, NH4I, NaN3, or NaCN gave complexes of type <(OC)3Mo(μ-dppm)2Rh(CO)X> (X = Br, I, N3, or CN) in good yield. 31P-<1H> N.m.r. evidence suggests that <(OC)3Mo(μ-dppm)2Rh(CO)Br> occurs in two forms, a major form analogous to (1a) and a minor form (3) which possibly has a semibridging CO.Complex (1a) or (2a) reacts with NaBH4 to give a hydrido complex <(OC)3Mo(μ-dppm)2Rh(CO)H>.Treatment of (2a) with Li(C<*>CR) gave the acetylide comlexes <(OC)3Mo(μ-dppm)2(μ-C<*>CR)Rh(CO)> (R = Me, Ph, or C6H4Me-p) (4a)-(4c).Treatment of (1a) or (2a) with MeCN in the presence of PF6^- gave the complex <(OC)3Mo(μ-dppm)2Rh(CO)(NCMe)>PF6.The previously described <(OC)3Mo(μ-dppm)2Ir(CO)2>Pf6 react similarly with NCR (R = Me or Ph) to give the analogous nitrile complexes <(OC)3Mo(μ-dppm)2Ir(CO)(NCR)>PF6.Treatment of (1a) or (2a) with Bu^tNC gives <(OC)3Mo(μ-dppm)2Rh(CO)(CNBu^t)>⁺.Crystals of the compound <(OC)3Mo(μ-dppm)2(μ-C<*>CMe)Rh(CO)> are triclinic, space group P<*>, with a = 1802.2(3), b = 1303.2(3), c = 1228.2(3) pm, α = 114.77(2), β = 97.52(2), γ = 102.02(2) degree, and Z = 2; final R'factor 0.037 for 6006 observed reflections.The structure shows that the two metal centres are asymmetrically bridged by methylacetylide which forms a ? bond to rhodium and a side-on ? bond to molybdenum.

Full text of DOI:10.1039/DT9870002171

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