Crystal and molecular structure of a bis(tricarbonyliron) complex containing bridging isopropylidenamido and 2-propanoximato(O, N) ligands

Abstract

The structure of g-isopropylidenamido-u-2-propanoximato(0,7V)-bis(tricarbonyliron) has been determined by a crystallographic study. Crystals of this complex are triclinic, space group Pi, with reduced cell parameters a = 12.061 (10) A, b = 9.119 (7) A, c = 8.599 (7) Á, a = 66.81 (2)°, ß = 99.94 (3)°, y = 107.08 (2)°. Observed and calculated (Z = 2) densities are 1.60 (4) and 1.63 g/cm3, respectively. Least-squares refinement, based upon 1363 independent nonzero counter data, converged to a conventional discrepancy factor of 0.036. The binuclear structure contains two tricarbonyliron groups linked by bridging N=C(CH3)2 and ON=C(CH3)z ligands and by an iron-iron bond of length 2.484 (2) Á. The 2-propanoximato ligand bridges diatomically, forming a novel Fe-N-O-Fe linkage. Relatively little perturbation of the orientations of the Fe(CO)3 groups or of the iron coordination spheres is observed, despite the presence of both monatomic and diatomic bridging ligands. Distances and angles within the ON=C(CH3)2 group are consistent with the presence of a C=N double bond (1.291 (7) Á) and a N-0 single bond (1.351 (6) Á). The Fe-N distances range in length from 1.902 (4) to 1.982 (5) A, with the shorter distances involving the monatomically bridging isopropylidenamido ligand. The Fe-0 bond length is 1.952 (4) A.

Structure of bis(μ-ethylideneamido)-bis(tricarbonyliron)(Fe–Fe)

“…The Fe2(CO)6N 2 core is typical of a wide set of compounds Piron, Piret & Van Meerssche, 1967;Jarvis, Job, Kilbourn, Mais, Owston & Todd, 1967;Bright & Mills, 1967;Bagga, Baikie, Mills & Pauson, 1967;Doedens, 1968Doedens, , 1970Dahl, Costello & King, 1968;Doedens & Ibers, 1969;Little & Doedens, 1972;Madden, Carty & Birchall, 1972;Carty, 1972;Khare & Doedens, 1976;Tikhonova et al, 1976) which can be collected into two classes: (1) with a N-N bond, and (2) without a N-N bond: our complex belongs to the second class, owing to the long N...N distance [2.388 (9) A].…”

“…(d) Present paper. (e) Khare & Doedens (1976); the reported values refer to the second nitrogenated ligand.…”

“…Other similar complexes with a short N... from planarity around C=N, but the lack of data for [FeE(CO)6(N=C6H10)2], [Fe2(CO)6(N=CPh2)2] and [Fee(CO)6(N2CE3H18)] does not allow a direct comparison. On the other hand, indirect support for the last conclusion is offered by [Fe2(CO)6{ON=C(CH3)E}-{N-C(CH3)z}] (Khare & Doedens, 1976) and [MnE(CO)~{N=C(CFa)2} 2] (Churchill & Lin, 1975) which have a greater N...N distance and do not show any particular distortion at the N atom of the bridging ligand. Another reason for the ligand distortion can be offered by the value of the H(1)...H(1) intermolecular contact (Table 5) which is shorter than twice the van der Waals radius (1.2 A).…”

Syntheses and molecular structures of ruthenium carbonyl complexes containing 1,2-naphthoquinone-1-oximate ligands

“…6) Å]. 15 The nqo ligands in 4 act as an unprecedented 5e Ϫ donor rather than a 3e Ϫ donor as in the case for both 1b and 2. Together with the eight terminal carbonyls, cluster 4 is electron precise with a cluster valence electron (CVE) count of 50 which is expected for a trinuclear cluster with two metal-metal bonds.…”