Unbridged homo and hetero dinuclear complexes of Group 6 and 8 metals: synthesis, characterization and comparison of X-ray crystallographic data

Synthesis and characterization of heteromultinuclear Ni/M clusters (M = Fe, Ru, W) including a paramagnetic (NHC)Ni-WCp*(CO)3 heterobinuclear complex

A diverse range of heteromultinuclear NiI/[MCO] clusters (MCO = CpFe(CO)2, CpRu(CO)2, Cp*W(CO)3) supported by a N-heterocyclic carbene ligand have been synthesized by reacting the NiI precursor, [IPrNi(μ-Cl)]2, with [MCO]- reagents under various conditions. Clusters with Ni2Fe2, NiFe2, Ni2Ru, Ni2Ru2, NiRu2, and Ni2W, and NiW cores were all characterized using NMR and IR spectroscopies and X-ray crystallography. The NiI-containing paramagnetic heterobinuclear species, IPrNi-Wp* (7), was further characterized by EPR spectroscopy and DFT calculations. Notably, unlike previously studied (NHC)CuI-[MCO] derivatives, complex 7 was found to coordinate Lewis bases like 3-chloropyridine to produce (IPr)(3-Clpy)NiWp* (9). Complex 9 further underwent thermolytic C-Cl activation, proposed to involve NHC-free [(3-Clpy)Ni(μ-Wp*)]2 (10), to provide the C-arylated N-heterocyclic carbene product, [IPr(py-3-yl)]+[Cp*WCl2(CO)2]- (11).

Unsaturation in binuclear heterometallic carbonyls: the cyclopentadienyliron manganese carbonyl CpFeMn(CO)n system as a hybrid of the Cp2Fe2(CO)n and Mn2(CO)n systems

The structures and energetics of the CpFeMn(CO)_n (n = 7, 6, 5) have been examined by density functional theory.

Xenophilic Complexes Bearing a TpR Ligand, [TpRM?M?Ln] [TpR=TpiPr2, Tp# (TpMe2,4-Br); M=Ni, Co, Fe, Mn; M?Ln=Co(CO)4, Co(CO)3(PPh3), RuCp(CO)2]: The Two Metal Centers are Held Together not by Covalent Interaction but by Electrostatic Attraction

A series of dinuclear complexes, [Tp(R)M--M'L(n)] [Tp(iPr(2) )M--Co(CO)(4) (1; M=Ni, Co, Fe, Mn); Tp(#)M--Co(CO)(4) (1'; M=Ni, Co); Tp(#)Ni--RuCp(CO)(2) (3')] (Tp(iPr(2) )=hydrotris(3,5-diisopropylpyrazolyl)borato; Tp(#) (Tp(Me(2),4-Br))=hydrotris(3,5-dimethyl-4-bromopyrazolyl)borato), has been prepared by treatment of the cationic complexes [Tp(iPr(2) )M(NCMe)(3)]PF(6) or the halo complexes [Tp(#)M--X] with the appropriate metalates. Spectroscopic and crystallographic characterization of 1-3' reveals that the tetrahedral, high-spin Tp(R)M fragment and the coordinatively saturated carbonyl-metal fragment (M'L(n)) are connected only by a metal-metal interaction and, thus, the dinuclear complexes belong to a unique class of xenophilic complexes. The metal-metal interaction in the xenophilic complexes is polarized, as revealed by their nu(CO) vibrations and structural features, which fall between those of reference complexes: covalently bonded species [R--M'L(n)] and ionic species [M'L(n)](-). Unrestricted DFT calculations for the model complexes [Tp(H(2) )Ni--Co(CO)(4)], [Tp(H(2) )Ni--Co(CO)(3)(PH(3))], and [Tp(H(2) )Ni--RuCp(CO)(2)] prove that the two metal centers are held together not by covalent interactions, but by electrostatic attractions. In other words, the obtained xenophilic complexes can be regarded as carbonylmetalates, in which the cationic counterpart interacts with the metal center rather than the oxygen atom of the carbonyl ligand. The xenophilic complexes show divergent reactivity dependent on the properties of donor molecules. Hard (N and O donors) and soft donors (P and C donors) attack the Tp(R)M part and the ML(n) moiety, respectively. The selectivity has been interpreted in terms of the hard-soft theory, and the reactions of the high-spin species 1-3' with singlet donor molecules should involve a spin-crossover process.