我們利用二胺基吡啶配基，Me[N2N]2- (2,6-bis(trimethylsilylamido)pyridine)與鈮的氯化物NbCl3(DME) (DME = H3COCH2CH2OCH3)反應，可以得到具有較短鈮-鈮雙鍵的低配位低氧化態錯合物Nb2(mu-Me[N2N])3 (1)，接著，我們將1與二氯化錫反應可以得到(ClNb)(mu-Me[N2N])3(Nb) (2)。另一方面，我們將具有高反應性鈮-鈮雙鍵的1與有機疊氮化合物反應，當1與MesN3 (Mes = 2,4,6-Me3C6H2)反應可以得到(MesN3Nb)2(mu-Me[N2N])3 (3)，另外將1與Me3SiN3反應可以得到亞胺基鈮錯合物(TMSNNb)2(mu-Me[N2N])3 (4) (TMS = Me3Si)與另一個有趣的產物，(TMSNNb)(mu-Me[N2N])2(mu-Me[NNN])(NbN3) (5)。另一方面，我們將1與氧族小分子(氧、硫、硒、碲)反應，也可以得到一系列有趣的錯合物，我們將1分別與硫、硒、碲反應可以得到主要產物為(ENb)2(mu-Me[N2N])3 (E = S, 7; Se, 8; Te,10)與次要產物為(SeNb)(mu-Me[N2N])2(mu-Me[NNN])(Nb) (9)，如將1與氧化吡啶(Pyridine N-oxide)反應可以進行氧原子的轉移而得到(ONb)2(mu-Me[N2N])3 (6)。
我們也利用立體阻礙較大的二胺基吡啶配基，Li2t-BuPh2[N2N] (t-BuPh2[N2N] = 2,6-bis(tert-butyldiphenylsilylamido)pyridine)、Li2i-Pr[N2N] (i-Pr[N2N] = 2,6-bis(triisopropylsilylamido)pyridine)與兩價釩(VCl2(THF)4、VCl2(TMEDA)2 (TMEDA = N,N,N',N'-tetramethylethylenediamine))反應。將Li2t-BuPh2[N2N]與0.5或1當量VCl2(THF)4反應分別可以得到[(THF)V](mu-t-BuPh2[N2N])2(Na) (11)、[(THF)2V]2(mu-t-BuPh2[N2N])(mu-Cl)2 (12)，將Li2i-Pr[N2N]與一當量VCl2(TMEDA)2反應可以得到[(TMEDA)V]2(mu-i-Pr[N2N])(mu-Cl)2 (13)，12、13都是具有釩-釩單鍵的雙釩金屬錯合物。
除了第五族過渡金屬外，我們也將配基與第六族過渡金屬反應。首先，我們將Li2Me[N2N]與氯化亞鉻反應，因為立體阻礙太小，因此我們得到了四個鉻與一個氯組成的五員環錯合物Cr4(mu-Me[N2N])3(Me[NNNH])(mu-Cl) (14)，將14還原(用一當量KC8)可以得到四個鉻形成四員環的錯合物Cr4(mu-Me[N2N])4 (15)，我們改用立體阻礙較大的配基，Li2t-BuMe2[N2N] (t-BuMe2[N2N] = 2,6-bis(tert-butyldimethylsilylamido)pyridine)、Li2t-Bu2Me[N2N] (t-Bu2Me[N2N] = 2,6-bis(di-tert-butylmethylsilylamido)pyridine)、Li2i-Pr[N2N]分別與氯化亞鉻反應可以得到[(THF)Cr]2(mu-t-BuMe2[N2N])2 (16)、[(THF)Cr]2(mu- t-Bu2Me[N2N])2 (17)、 [(THF)Cr]2(mu-i-Pr[N2N])2 (18)，如果與氯化鉻反應則可得到[(THF)2LiCl2Cr]2(mu-i-Pr[N2N])(mu-Cl)2 (21)、[(THF)ClCr]2(mu-t-BuPh2[N2N])(mu-Cl)2 (22)，另一方面，我們將18與一當量還原劑(KC8)及皇冠醚(18-crown-6 ether)反應可以得到很特別的鉻(Ⅱ)、鉻(I)的雙鉻錯合物{Cr2(mu-i-Pr[N2N])2}[K(18-crown-6 ether)(THF)2] (19)，接著，將19與硒反應則可以得到Cr25+，混合價數的雙鉻錯合物{Cr2(mu-i-Pr[N2N])2(mu-Se)}[K(18-crown-6 ether)(THF)2] (20)，硒原子橋接在兩個鉻之間，三者形成一個三員環的結構。
另一方面，我們改用另一種二胺基吡啶配基，Li2dipp[N2N] (dipp[N2N] = (2,6-bis(diisopropylphenylamido)-4-methylpyridine))，與氯化亞鉻反應可以得到Cr(□-dipp[N2N])2[Cr(Et2O)] (23)，將23與一當量還原劑(KC8)及皇冠醚(18-crown-6 ether)反應，可以得到結構與19相似的錯合物{Cr2(mu-dipp[N2N])2}[K(18-crown-6 ether)(Et2O)] (24)，有趣的是，如果將23與三當量的還原劑(KC8)反應則可以得到鉻(I)-鉻(I)的鉻-鉻五鍵錯合物{Cr2(mu-dipp[N2N])2}(K2) (25)。
接著，我們將配基與WCl3(DME)反應可以得到一系列鎢三價的錯合物，W2(mu-Me[N2N])3 (26)、(ClW)2(mu-t-BuMe2[N2N])2 (27)、(ClW)2(mu-i-Pr[N2N])2 (28)，這些錯合物都具有鎢-鎢三鍵。
我們還將配基與第七族的過渡金屬起始物反應，將Li2t-BuPh2[N2N]與二氯化錳反應，可以得到Mn2(mu-t-BuPh2[N2N])2 (29)，兩個錳原子之間沒有鍵結，接著，我們將29與苯甲腈反應可以得到[(PhCN)Mn]2(mu-t-BuPh2[N2N])2 (30)，兩個苯甲腈接在錳上，兩個錳原子之間沒有鍵結。
我們利用X-ray單晶繞射分析，元素分析，核磁共振光譜等方法確定其結構。

A novel trivalent diniobium(III) complex supported by three bulky pyridyl diamido ligands Me[N2N]2- (Me[N2N] = 2,6-bis(trimethylsilylamido)pyridine) is prepared. The reaction between NbCl3(DME) (DME = H3COCH2CH2OCH3) and Li2Me[N2N] yields the title compound Nb2(mu-Me[N2N])3 (1). Reaction of 1 with SnCl2 produecs (ClNb)(mu-Me[N2N])3(Nb) (2). Treatment of 1 with TMSN3 (TMS = Me3Si), a major product, symmetric bisimido complex (TMSNNb)2(mu-Me[N2N])3 (4), and a minor product, asymmetric azido imido complex (TMSNNb)(mu-Me[N2N])2(mu-Me[NNN])(NbN3) (5) are obtained. A symmetric bis(mesityl azido) complex (MesN3Nb)2(mu-Me[N2N])3 (3) (Mes = 2,4,6-Me3C6H2) is obtained when 1 is treated with MesN3. Upon treatment of 1 with S, Se and Te gives rise to the formations of niobium(V) chalcogenide (ENb)2(mu-Me[N2N])3 (E = S, 7; Se, 8; Te,10) and (SeNb)(mu-Me[N2N])2(mu-Me[NNN])(Nb) (9) as respective major and minor products, concomitant with the rupture of the Nb＝Nb double bond. Moreover, 1 can also be doubly oxygenated via an oxygen atom transfer from pyridine N-oxide to produce (ONb)2(mu-Me[N2N])3 (6). The Nb＝Nb double bond of 1 can also be split upon addition of organic azides.
Treatment of VCl2(THF)4 with Li2t-BuPh2[N2N] (t-BuPh2[N2N] = 2,6-bis(tert-butyldiphenylsilylamido)pyridine) gives [(THF)V](mu-t-BuPh2[N2N])2(Na) (11) or [(THF)2V]2(mu-t-BuPh2[N2N])(mu-Cl)2 (12), but, on the other hand, reaction of VCl2(TMEDA)2 (TMEDA = N,N,N',N'-tetramethylethylenediamine) with Li2i-Pr[N2N] (i-Pr[N2N] = 2,6-bis(triisopropylsilylamido)pyridine) gives rise to [(TMEDA)V]2(mu-i-Pr[N2N])(mu-Cl)2 (13).
Interestingly, the reaction of CrCl2 with Li2Me[N2N] produces Cr4(mu-Me[N2N])3(Me[NNNH])(mu-Cl) (14), in which the core structure is a five-member ring. The addition of KC8 to 14 leads the isolation of Cr4(mu-Me[N2N])4 (15), in which the Cr metal core forms a four-member ring. The reaction of CrCl2 with more sterically hindered ligands Li2t-BuMe2[N2N] (t-BuMe2[N2N] = 2,6-bis(tert-butyldimethylsilylamido)pyridine), Li2t-Bu2Me[N2N] (t-Bu2Me[N2N] = 2,6-bis(di-tert-butylmethylsilylamido)pyridine), Li2i-Pr[N2N] produces [(THF)Cr]2(mu-t-BuMe2[N2N])2 (16), [(THF)Cr]2(mu- t-Bu2Me[N2N])2 (17), [(THF)Cr]2(mu-i-Pr[N2N])2 (18). Complexes 16, 17, 18 are similar in structures. Treament of Li2i-Pr[N2N] with CrCl3 produces [(THF)2LiCl2Cr]2(mu-i-Pr[N2N])(mu-Cl)2 (21). Furthermore, the reaction of 18 with KC8 in the presence of 18-crown-6 ether proudces a mixed-valence complex {Cr2(mu-i-Pr[N2N])2}[K(18-crown-6 ether)(THF)2] (19). Interestingly, treatment of 19 with Se gives a mixed-valence Cr25+ complex, {Cr2(mu-i-Pr[N2N])2(mu-Se)}[K(18-crown-6 ether)(THF)2] (20). Reaction of the bulkier ligand Li2dipp[N2N] and CrCl2 leads to the isolation of Cr(mu-dipp[N2N])2[Cr(Et2O)] (23). Treatment of 23 with KC8 and 18-crown-6 ether produces a mixed-valence Cr23+ complex {Cr2(mu-dipp[N2N])2}[K(18-crown-6 ether)(Et2O)] (24). Noteworthy is reduction of 23 with more than 3eq of KC8 produces a quintuply-bonded Cr22+ complexes {Cr2(mu-dipp[N2N])2}(K2) (25) with two K atoms embedded by phenyl rings and nitrogen atoms.
Treatment of Li2R[N2N] with WCl3(DME) gives a series of tungsten complexes, W2(mu-Me[N2N])3 (26), (ClW)2(mu-t-BuMe2[N2N])2 (27), (ClW)2(mu-i-Pr[N2N])2 (28); all of them display W-W triple bonds.
Furthermore, the reaction of MnCl2 and Li2t-BuPh2[N2N] leads to the isolation of Mn2(mu-t-BuPh2[N2N])2 (29). Treatment of 29 with PhCN produces [(PhCN)Mn]2(mu-t-BuPh2[N2N])2 (30).
All complexes presented are fully characterized by multi-nuclear NMR spectroscopy and X-ray diffraction.

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