The nitrido group is a versatile bridging ligand that can bind to two metal ions either
symmetrically or unsymmetrically. While dinuclear nitrido complexes containing
earlier and mid transition metals are well known, there are few heterometallic μ-nitrido
complexes with late transition metals such as platinum. This thesis reports on the
synthesis and reactivity of heterobimetallic platinum-ruthenium and iron-osmium
nitrido complexes.
In Chapter 2, the synthesis and structure of heterodinuclear platinum-ruthenium
complexes are described. Treatment of the previously reported Pt(II) cyclometalated
complex [Pt(C^N^C)(dmso)] (1) (H
2(C^N^C) = 2,6-di(4-tert-butylphenyl)pyridine;
dmso = dimethylsulfoxide) with [L
OEtM(N)Cl
2] (M = Ru, Os; L
OEt- = [Co(η
5-C
5H
5){P(O)(OEt)
2}
3]
-) afforded ai...[
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The nitrido group is a versatile bridging ligand that can bind to two metal ions either
symmetrically or unsymmetrically. While dinuclear nitrido complexes containing
earlier and mid transition metals are well known, there are few heterometallic μ-nitrido
complexes with late transition metals such as platinum. This thesis reports on the
synthesis and reactivity of heterobimetallic platinum-ruthenium and iron-osmium
nitrido complexes.
In Chapter 2, the synthesis and structure of heterodinuclear platinum-ruthenium
complexes are described. Treatment of the previously reported Pt(II) cyclometalated
complex [Pt(C^N^C)(dmso)] (1) (H
2(C^N^C) = 2,6-di(4-tert-butylphenyl)pyridine;
dmso = dimethylsulfoxide) with [L
OEtM(N)Cl
2] (M = Ru, Os; L
OEt- = [Co(η
5-C
5H
5){P(O)(OEt)
2}
3]
-) afforded air-stable heterometallic Pt(II)/M(VI) nitrido
complexes [L
OEtMCl
2(μ-N)Pt(C^N^C)] (M = Ru, Os) (M = Ru (2-1), Os (2-2) that
have been characterized by X-ray diffraction. The Ru-N and Pt-N(nitrido) distances in
2-1 [1.679(5) and 1.815(5) Å, respectively] are indicative of the Ru=N=Pt bonding
description. The oxidation of 2-1 with PhICl
2 yielded the Pt(IV)/Ru(VI) complex
[L
OEtRuCl
2(μ-N)PtCl
2(C^N^C)] (2-3). The Pt-N distance in the Pt(IV) complex 2-3 [1.893(3) Å] is significantly longer than that in the Pt(II) analogue 2-1 [1.815(5) Å]
because the π bonding between Pt and the Ru nitride is weakened when the oxidation state of Pt increases from +2 to +4. Treatment of 1 with [
nBu
4N][Ru(N)Cl
4] in
tetrahydrofuran (THF) afforded [
nBu
4N][(THF)Cl
4Ru(μ-N)Pt(C^N^C)] (2-4). Chloride
substitution of 2-4 with K[N(Ph
2PS)
2] afforded [{N(Ph
2PS)
2}
2Ru(μ-N)PtCl
2(C^N^C)]Cl (2-5) that has been characterized by X-ray diffraction. The short Pt-N bond distance in 2-5 [1.808(2) Å] is consistent with a Pt=N double bond.
Chapter 3 describes the synthesis and structure of heterometallic iron(IV) nitrido complexes. Treatment of [Fe(Pc)] (Pc
2- = phthalocyanine dianion) with [L
OEtOs(N)Cl
2]
afforded a novel trinuclear μ-nitrido complex [(Pc)Fe{L
OEtOsCl
2(μ-N)}
2] (3-1) that has
been characterized by X-ray diffraction. The Os-N and Fe-N(nitride) distances in 3-1
are 1.677(6) and 1.841(6) Å, respectively, and the Os-N-Fe angles are 170.0(4)
o. The
structural data of 3-1 is consistent with the Os(V)-Fe(IV)-Os(V) formulation. The
oxidation of 3-1 with [(4-BrC
6H
4)
3N](SbCl
6) in CH
2Cl
2 resulted in the appearance of absorption bands at 603 and 665 nm in the UV/visible spectrum that are diagnostic of
Pc cation radical. As such, the 1-electron oxidation product of 3-1 is formulated as a
Os(V)-Fe(IV) Pc cation radical complex, [(Pc
.+)Fe{L
OEtOsCl
2(μ-N)}
2]. Treatment of
[Fe(bpb)] (H
2bpb = 1,2-bis(pyridine-2-carboxamido)benzene), which was prepared in-situ
by Zn reduction of (
nBu
4N)[Fe(bpb)Cl
2], with [L
OEtRu(N)Cl
2] afforded the Ru(IV)-Fe(IV) nitrido complex [(L
OEtCl
2Ru(μ-N)Fe(bpb)] (3-2) that was characterized by
NMR spectroscopy. Similarly, [(L
OEtCl
2Ru(μ-N)Fe(tmtaa)] (H
2tmtaa = 7,16-dihydro-6,8,15,17-tetramethyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecane) was prepared
by the reaction of [Fe(tmtaa)] with [L
OEtRu(N)Cl
2] and characterized by NMR spectroscopy.
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