Heterobimetallic complexes of rhodium with platinum, silver, and gold containing bridging 2-[bis(diphenylphosphino)methyl]pyridine (PNP) ligands

Abstract

absorption isotherm may be constructed as in Figure 4. From such data, Hill plots15 may be constructed, Figure 5, which in turn give the apparent oxygen binding constants listed in Table I. The Hill plots show slopes of 0.56 ± 0.02, indicating a negative cooperativity between the Co binding sites.10 This translates as meaning that as oxygen is bound by the first cobalt sites, subsequent binding by further sites is inhibited. This is the reverse

Molecular geometry of M(NO)2 complexes: single crystal X-ray structure of Co(NO)2(C5H5N)2+BF4−, lability of the pyridine ligands of Co(NO)2(C5H5N)2+, and its relevance to the formation of the Co2(NO)3+ bimetallic core

“…In addition, regarding the synthesis of polymetallics containing pyridylphosphines as bridging ligands (see for example the references quoted in ref. 34), the functionalization of their N(Py) donor sites with M(N0) first row metallic fragments might result in nonbonded repulsions within the M(NO)(Py) moieties that are sufficiently destabilizing for opening up reaction pathways leading to the formation of unusual structures, as exemplified by the formation of Co,(NO),-(PN),+BP4-.…”

“…J. Chem. Downloaded from www.nrcresearchpress.com by 34 undertaken with co(No),(Py),+B~,-, which provided suitable crystals.…”

Synthetic and Structural Studies of the Coordination Behavior of 2-Pyridylbis(diphenylphosphino)methane

“…There does not appear to be any strong correlation between the observation of N,P vs P,P coordination and the hardness or softness of the metal center since both Co(II) (moderately hard) and Cd(II) (moderately soft) both show the former mode. With the exception of rhodium, 6,9 iridium, , and nickel, NPP does not appear to readily promote the formation of dinuclear complexes and those monometallic complexes in which it is only N,P or P,P coordinated have not been found to be useful precursors to heterobimetallic complexes. Neither does there seem to be any pattern to the lability of one arm of the ligand that would lead to its predictable function as a semilabile ligand in catalytic applications.…”

“…This and an analogue methylated on the pyridyl group have been the subjects of a limited number of reports 3-7 but it does not appear that there has been any systematic study of the chemistry of NPP-type ligands. To address this we sought first to determine the extent to which NPP would promote the formation of dinuclear complexes from mononuclear precursors as is well-established for its “parent” ligand bis(diphenylphos-phino)methane (DPPM) and as has been found to occur with Rh(I) and Ir(I) systems. , A second goal of the study was to ascertain if monometallic NPP complexes could function as metalloligands in the synthesis of hetero bimetallic complexes. Additionally it was of interest to confirm the coordination mode of NPP in examples of its complexes where this had been only inferred from limited spectroscopic data .…”