Michael Harmjanz

Syntheses and structures of transition metal thiolate complexes containing the new bis(tetramethylguanidine) ligand btmgp

Abstract The syntheses, spectroscopic and structural characterizations of the first iron and copper thiolate guanidine complexes are described. Reactions of the neutral complexes [CuI(btmgp)] and [FeI2(btmgp)] [btmgp=1,3-bis(N,N,N′,N′-tetramethylguanidino)propane] with different uni- and bi-dentate thiolate ions yield the three-coordinate complex [Cu(S-2,4,6-tBu3C6H2)(btmgp)] (1) and the four-coordinate complexes [Fe(S-2,4,6-iPr3C6H2)2(btmgp)] (2) and [Fe(SiMe2(C6H4S)2)(btmgp)] (3) respectively. Starting with [Fe(N(SiMe3)2)2], btmgp and the dithiol SiMe2(C6H4SH)2, an alternative procedure for the preparation of 3 is reported, demonstrating a useful synthetic approach towards neutral, N/S mixed coordinated Fe(II) complexes. The X-ray structure analyses of 1–3 reveal trigonal planar (2N/1S) (1) and tetrahedral (2N/2S) (2, 3) coordination environments around the metal centers.

1,3-Bis(N,N,N′,N′-tetramethylguanidino)propane: synthesis, characterization and bonding properties of the first bidentate, peralkylated guanidine ligand

The first bidentate, peralkylated guanidine based ligand has been synthesized and its complexation chemistry examined by the preparation of three representative coordination compounds. The novel chelate ligand 1,3-bis(N,N,N′,N′-tetramethylguanidino)propane (btmgp, 1) has been synthesized by the reaction of N,N,N′,N′tetramethylguanidine (TMG) with 1,3-dibromopropane and subsequent deprotonation of the resulting guanidinium salt with sodium ethoxide. The bifunctional N-donor compound was treated with copper(I) iodide, copper(II) chloride and iron(II) iodide in a 1∶1 molar ratio to yield the corresponding electroneutral complexes [CuI(btmgp)] 2, [CuCl2(btmgp)] 3 and [FeI2(btmgp)] 4. The structures of the dihydrochloride of 1 (1b) and of the complexes 2–4 have been determined by X-ray crystallography. A comparison of the molecular structures (2–4) shows that, in each case, btmgp acts as a bidentate ligand which is able to stabilize not only trigonal-planar (2), but also (distorted) square-planar (3) and tetrahedral coordination environments (4).

First rhenium complexes based on cyclotriphosphazene scaffolds with exocyclic pyrazolyl substituentsElectronic supplementary information (ESI) available: experimental details. See http://www.rsc.org/suppdata/cc/b2/b203254f/

Functionalized cyclotriphosphazenes with two or six pyrazolyl substituents have been employed for the preparation of rhenium carbonyl complexes; depending on the nature of the ligand system rhenium complexes with either gem-N2, gem-N3 or non-gem-N3 coordination modes can be prepared.

A convenient synthesis of porphodimethenes and their conversion to trans-porphyrins with two functionalized meso-naphthyl substituents

The Mac Donald-type 2 + 2 condensation of the readily available 5-mesityldipyrromethane with acenaphthenequinone leads to the trans (syn and anti) porphodimethenes, respectively, which, after treatment with KOH or NaOMe in THF and subsequent oxidation with air, yield the corresponding trans-8-carboxynaphthylporphyrins or their esters.

Aryl isonitrile binding to [Fe4S4] clusters:formation of [Fe4S4]+ and[{Fe4S4}2]2 cores

Aryl isonitriles (ArNC; Ar = 2,4,6-Me 3 C 6 H 2 NC 1, 2,6-Me 2 C 6 H 3 NC 2) react with [Fe 4 S 4 I 4 ] 2- 3 and [Co(η-C 5 H 5 ) 2 ] to afford [Fe 4 S 4 I(ArNC) 9 ] 4a, b; substitution of iodide by RS - (R = 2,4,6-Me 3 C 6 H 2 ) yields [Fe 4 S 4 - (SR)(ArNC) 9 ] 5 and reaction of [Fe 4 S 4 I(2,4,6-Me 3 C 6 H 2 NC) 9 ] 4b with KB(4-Cl-Ph) 4 leads to [{Fe 4 S 4 (2,4,6-Me 3 C 6 H 2 NC) 9 } 2 ][B(4-ClPh) 4 ] 2 6.

Porphodimethenes/porphyrins: redox-switchable tetrapyrrolic macrocycles

Utilizing a general two-step procedure, a new class of porphodimethene macrocycles has been prepared, which can be easily converted to porphyrins bearing two 8-functionalized naphthalene spacers. Through straightforward modifications in the precursor molecules, macrocycles with a wide range of steric and electronic attributes can be isolated. With these simple ligands, metal-porphyrin complexes exhibiting interesting properties can be produced. For example, when two reactive groups are poised above the porphyrin, a reversible ring closure can take place under mild conditions, allowing for potential recognition sites close to a metal center to be electrochemically and chemically activated and deactivated. This intramolecular porphodimethene-porphyrin interconversion offers many exciting possibilities for the development of catalysis adept at specific transformations and for the design of novel sensors or photosensitizers.