Heterobimetallics of nickel-iron dinitrosyl: electronic control by chelate and diatomic ligands.

Reaction of [PPN][Fe(NO)2(SePh)2] (1) with dimeric [Ni(mu-SCH2CH2SCH2CH2S)]2 in the presence of additional NO2- produced the neutral heterobimetallic [(ON)Ni[(mu-SCH2CH2)2S]Fe(NO)2] complex (2). The X-ray crystal structures of 1 and 2 show distorted tetrahedral iron dinitrosyl groups, assigned according to the Feltham-Enemark notation as [Fe(NO)2]9 The Fe-NO bonds are off linearity by an average of approximately equals 10 degrees for compounds 1 and 2, while a more linear Ni-NO coordination with a Ni-NO distance of 1.644(2) A was found in 2. The v(NO) value of complex 2 is consistent with an assignment for [Ni(NO)]9 of Ni0(NO)+ as is known for analogous phosphine derivatives, P3Ni0(NO)+. EPR signals of g values = 2.02-2.03 confirmed the existence of the odd electron in the chalcogenated [Fe(NO)2]9 compounds. Two [Fe(NO)2]10 complexes coordinated by the nickel(II) dithiolate, (bismercaptoethanediazacyclooctane)nickel(II), (Ni-1), (Ni-1)Fe(CO)(NO)2 and (Ni-1)Fe(NO)2, were prepared for comparison to the Ni0(NO)+ derivative and other monomeric and homodimetallic derivatives of the Fe(NO)2 fragment. While the oxidation level of Fe(NO)2 is the primary determinant of v(NO) values, they are also highly sensitive to ancillary ligands and, thereby, the distal metal influence through the bridging thiolate donor.