| Abstract |
Reaction of the palladium(II) and platinum(II) isocyanide complexes cis[MCl2(CNR)2] [M = Pd, R = C6H3(2,6-Me-2) (Xyl), 2-Cl-6-MeC6H3, cydohexyl (Cy), t-Bu,C(Me)(2)CH2(Me)(3) (1,1,3,3-tetramethylbuth-l-yl abbreviated as tmbu); M = Pt, R = Xyl, 2-Cl-6MeC(6)H(3),Cy, t-Bu, and tmbu] with N,N -diphenylguanidine (DPG) leads to DPG-derived metal-bound deprotonated acyclic diaminocarbene (ADC) species. This reaction occurs via a two-step process, involving the initial coupling of the guanidine with one of the isocyanides and leading to deprotonated monocarbene monochelated species, while the next addition grants the deprotonated bis-carbene bis-chelated metal compounds. DPG behaves as nucleophile, deprotonating base, and chelator. The addition of DPG proceeded with different regioselectivity depending on the metal center and, in a larger extent, on the substituent R in RNCs. The X-ray diffraction studies for the deprotonated mono-and bis-carbene complexes confirmed the regioisomerism of these species and allowed the identification of ADC protolytic forms stabilized in the solid-state. ID (H-1 and C-13\H-1\) and 2D (H-1,H-1-NOESY; H-1,N-15-HSQC; H-1,N-15-HMBC)solution NMR of the obtained systems demonstrated their configuration isomerism accompanied by prototropic tautomerism. Together, the solid-state and solution data provide an insight into the flexible character of ADC species. |
