Homo and heteropolymetallic Group 4 molecular nitridesElectronic supplementary information (ESI) available: Kinetic data and analyses for the dynamic NMR spectroscopy study for compound 9, selected lengths and angles for the two independent molecules of compound 13, and a view along the a axis of the crystal lattice of compound 15. CCDC 1415001-1415004. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5dt02836a

Treatment of [{Ti(η 5 -C 5 Me 5 )(μ-NH)} 3 (μ 3 -N)] ( 1 ) with zirconium or hafnium tetrachloride adducts [MCl 4 (thf) 2 ] affords complexes [Cl 3 M{(μ 3 -N)(μ 3 -NH) 2 Ti 3 (η 5 -C 5 Me 5 ) 3 (μ 3 -N)}] (M = Zr ( 2 ), Hf ( 3 )). Titanium chloride complexes [Cl 2 Ti{(μ 3 -N) 2 (μ 3 -NH)Ti 3 (η 5 -C 5 Me 5 ) 3 (μ 3 -N)}] ( 4 ) and [(Me 2 NH)ClTi{(μ 3 -N) 3 Ti 3 (η 5 -C 5 Me 5 ) 3 (μ 3 -N)}] ( 5 ) are obtained by reaction of 1 with [TiCl 4− x (NMe 2 ) x ] ( x = 2, 3). The dimethylamine ligand in 5 is displaced by pyridine to give the analogue complex [(py) 2 ClTi{(μ 3 -N) 3 Ti 3 (η 5 -C 5 Me 5 ) 3 (μ 3 -N)}] ( 6 ). Treatment of the titanium chloride complexes 4 and 5 with sodium cyclopentadienide or lithium bis(trimethylsilyl)amide reagents leads to the cube-type nitrido derivatives [RTi{(μ 3 -N) 3 Ti 3 (η 5 -C 5 Me 5 ) 3 (μ 3 -N)}] (R = η 5 -C 5 H 5 ( 7 ), N(SiMe 3 ) 2 ( 8 )). The reaction of the zirconium trichloride complex 2 with [Tl(C 5 H 5 )] yields exclusively the dichloride-monocyclopentadienyl derivative [(η 5 -C 5 H 5 )Cl 2 Zr{(μ 3 -N)(μ 3 -NH) 2 Ti 3 (η 5 -C 5 Me 5 ) 3 (μ 3 -N)}] ( 9 ). However, the treatment of 2 with excess [Na(C 5 H 5 )] causes further chloride replacement in 9 and subsequent cyclopentadiene elimination to give [(η 5 -C 5 H 5 )Zr{(μ 3 -N) 3 Ti 3 (η 5 -C 5 Me 5 ) 3 (μ 3 -N)}] ( 10 ) via intermediates [(η 5 -C 5 H 5 ) 2 ClZr{(μ 3 -N)Ti 3 (η 5 -C 5 Me 5 ) 3 (μ-NH) 2 (μ 3 -N)}] ( 11 ) and [(η 5 -C 5 H 5 )ClZr{(μ 3 -N) 2 (μ 3 -NH)Ti 3 (η 5 -C 5 Me 5 ) 3 (μ 3 -N)}] ( 12 ). Treatment of 2 or 9 with [Mg(C 5 H 5 ) 2 ] leads to the magnesium derivative [(η 5 -C 5 H 5 )Mg(μ-Cl) 2 (η 5 -C 5 H 5 )Zr{(μ 4 -N)(μ 3 -N)(μ 3 -NH)Ti 3 (η 5 -C 5 Me 5 ) 3 (μ 3 -N)}] ( 13 ), which can be visualized as a result of the incorporation of one [Mg(η 5 -C 5 H 5 )Cl] moiety to complex 12 . In contrast to the metathesis process with [M(C 5 H 5 ) x ] derivatives and subsequent C 5 H 6 eliminations, the reaction of 2 with potassium pentamethylcyclopentadienide in toluene produces the paramagnetic derivative [K(μ-Cl) 3 Zr{(μ 3 -N)(μ 3 -NH) 2 Ti 3 (η 5 -C 5 Me 5 ) 3 (μ 3 -N)}] ( 14 ) and C 10 Me 10 . Complex 14 reacts with one equivalent of 18-crown-6 or cryptand-222 to give the molecular complex [(18-crown-6)K(μ-Cl) 3 Zr{(μ 3 -N)(μ 3 -NH) 2 Ti 3 (η 5 -C 5 Me 5 ) 3 (μ 3 -N)}] ( 15 ) or the ion pair [K(crypt-222)][Cl 3 Zr{(μ 3 -N)(μ 3 -NH) 2 Ti 3 (η 5 -C 5 Me 5 ) 3 (μ 3 -N)}] ( 16 ). The X-ray crystal structures of 2 , 8 , 13 and 15 have been determined. A trich