Tito Lumini

Synthesis, crystal structures, and solution dynamics of some mono(2,4-dimethylpentadienyl)ruthenium(II) complexes

The reaction of [Ru(η5-C7H11)2H]BF4 (1; (η5-C7H11) = η5-2,4-dimethylpentadienyl (DMP)) with 2-electron or cyclic 6-electron ligands gives the salts [Ru(η5-C7H11)L3]BF4 (L  CO, PMe3, P(OMe)3, CH3CN; L3 = 1,1,1-tris(diphenylphosphinomethyl)ethane) and [Ru(η5-C7H11)(ηn-ring)]BF4 ((ηn-ring) = η6-cyclohepta-1,3,5-triene, η-cycloocta-1,3,5,7-tetraene, η6-arene, η5-thiophene). In the presence of a halide salt, 1 reacts with 4-electron diene ligands to give neutral [Ru(η5-C7H11)(diene)X] complexes (X  I, Cl, and (diene) = η4-buta-1,3-diene; η4-2,3-dimethylbuta-1,3-diene, η2:η2- cycloocta-1,5-diene) and with 2-electron ligands to give neutral [Ru(η2-C7H11)L2X] complexes (X  I, Br, Cl and L  CO, P(OMe)3, PMe3; X  I and L2 = bis(diphenylphosphino)ethane; X  Cl and L2 = N,N,N′,N′-tetramethylethylenediamine). [Ru(η5-C6H7)(η4-C 6H8)I] is the product of the reaction of 1 with cyclohexa-1,3-diene and KI. The complexes [Ru(η5-C7H11)(P(OMe)3)3]BF4 and [Ru(η5-C7H11)L2I] (LCO, P(OMe)3) have been crystallographically characterized. Complexes of the type [Ru(η5-C7H11)L3]+ and [Ru(η5-C7H11)L2X] exhibit dynamic behaviour in solution due to rotation of the DMP ligand with respect to the RuL3 or RuL2X groups, and activation energies for twelve of the complexes have been evaluated. Exchange of free and coordinated acetonitrile in solutions of [Ru(η5-C7H11)(NCCH3)3]BF4 is non-stereospecific and associative in character.

Hydrogen migration to acyclic pentadienyl ligands: The reactions of (η5-2,4-dimethylpentadienyl) (η4-2,4-dimethylpenta-1,3-diene)(L)rutheni

Diene-for-diene substitutions occur on reaction of the title complexes [Ru(η5-C7H11)(η4-C7H12)L]BF4 (L  tBu with cyclohexa-1,4-diene to give [Ru(η5-C6H7)(η4-C7H12)L]BF4 (L  tBuNC (19), CO (20)), and on react : η2-C8H12)(CNtBu)]BF4(26). All the apparent pentadienyl-for-pentadienyl substitutions are suggested to occur via initial dis

Crystal structure and fluxional behaviour in solution of [Rh4(CO)6(µ-Me2PCH2PMe2)3]Electronic supplementary information (ESI) available: regression of the Eyring plot of [Rh4(CO)6(µ-Me2PCH2PMe2)3] as measured by 13C–NMR between 169 and 293 K in CD2Cl2. 31P–NMR spectra of [Rh4(CO)6(µ-Me2PCH2PMe2)3] in CD2Cl2 at three different temperatures. See http://www.rsc.org/suppdata/dt/b2/b210986g/

[Rh-4 (CO)(6) (mu-Me2PCH2PMe2)(3)], the first example of a hexasubstituted derivative of Rh-4(CO)(12), has a ground state geometry in the solid state and in solution of C-s symmetry with four edge-bridging carbonyls and with each diphosphine ligand bridging one edge of the same Rh-3 face. The result is an imbalance of the formal electron count at two rhodium atoms. As observed by C-13- and P-31-NMR, the mobility of the ligands is restricted to one mu-CO eta-CO site exchange which astonishingly does not average dynamically the electron count on all four metal atoms.

Synthesis of rhodium(III)-pyridine complexes: an electrophoretic and chromatographic study

Abstract The synthetic methods for the preparation of rhodium(III)–pyridine complexes were examined using zone electrophoresis and thin-layer chromatography. Most syntheses produce a mixture of three to four complexes. Fresh solutions of commercial RhCl 3 · n H 2 O contain as many as ten electrophoretically different species. A yellow electrophoretically pure Rh(py) 3 Cl 3 (presumably the fac form) could be prepared, which in dilute acid converts into another neutral species, presumably the mer form. These could be separated by thin-layer chromatography on cellulose. The importance of examining the purity of monodentate complexes prepared by the usual synthetic methods is stressed.

Bis(diphosphino)methanide and hydride derivatives of Ir4(CO)12

The reaction of [Ir4(CO)10(μ-(Ph2P)2CH2)] with dried KOH forms [Ir4(CO)10(μ-(Ph2P)2CH)]− which subsequently converts into [Ir4(CO)9(μ3-(Ph2P)2CH)]−, a rare example of an Ir cluster with an Ir–C bond (average 2.274(8) A). The same reaction with the weaker base 1,8-diazobicyclo[5.4.0]undec-7-ene or with K2CO3 in wet CH2Cl2 under CO affords the anion [HIr4(CO)9(μ-(Ph2P)2CH2)]−, a hydride-cluster with an unusually long Ir–H distance (2.08(6) A at 90 K). Intramolecular CO scrambling is observed in CD2Cl2 solution above 200 K, preserving the terminal–axial position of the hydride ligand.