Bis(heptalene) "submarine" metal dimer sandwich compounds (C12H10)2M2 (M = Ti, V, Cr, Mn, Fe, Co, Ni).
The bis(heptalene)dimetal complexes (C12H10)2M2 of the first row transition metals from Ti to Ni are predicted by density functional theory to exhibit "submarine" sandwich structures with a pair of metal atoms sandwiched between the two heptalene rings. For the early transition metal derivatives (C12H10)2M2 (M = V, Cr) there are two types of such structures. In one structural type the metals are sandwiched between two heptahapto heptalene rings with metal-metal distances (3.5-3.8 Å) too long for direct metal-metal bonding. The other type of (C12H10)2M2 (M = V, Cr, Mn) structure has a pair of bonded metal atoms sandwiched between a fully bonded heptalene ligand and a heptalene ligand bonded to the metals only through an eight-carbon heptafulvene subunit, leaving an uncomplexed cis-1,3-diene unit. The formal metal-metal bond orders in these latter structures are 3, 2, and 1 for M = V, Cr, and Mn with predicted bond lengths of 2.5, 2.7, and 2.8 Å, respectively. For (C12H10)2Fe2 a singlet structure with each iron atom sandwiched between a hexahapto and a tetrahapto heptalene ring is energetically preferred over an alternate structure with ferrocene-like iron atoms sandwiched between two pentahapto heptalene rings. Partial bonding of each heptalene ring to the metal atoms occurs in the late transition metal derivatives (C12H10)2M2 (M = Co, Ni). This leads to an unsymmetrical structure for the cobalt derivative and a structure for the nickel derivative with each nickel atom sandwiched between a trihapto ligand and a tetrahapto ligand.
School of Physics and Chemistry, Research Center for Advanced Computation, Xihua University, Chengdu, 610039, China.
Huidong
H
Li
Hao
H
Feng
Weiguo
W
Sun
Qunchao
Q
Fan
Yaoming
Y
Xie
R Bruce
RB
King
Henry F
HF
Schaefer
D003035:Cobalt / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D007501:Iron / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D009532:Nickel / Q000737:chemistry; D011108:Polymers / Q000737:chemistry
D056831:Coordination Complexes; D008024:Ligands; D011108:Polymers; D003035:Cobalt; D009532:Nickel; D007501:Iron